1. Is it possible to specify a displacement and then have STAAD analyze a frame to give me a corresponding load (the load that would have been required to produce that displacement)?
2. I am applying a UBC seismic load on a bridge. The analysis engine reports an error message which says that:EITHER NA OR NV FACTOR HAS NOT BEEN SPECIFIED WHILE SEISMIC ZONE HAS BEEN SPECIFIED AS 4.
3. I would like to create a REPEAT LOAD case whose constituent load cases are themselves REPEAT LOAD cases. Is this allowed?
4. After determining the lateral loads using Staad UBC seismic analysis in a first file, I note down the lateral loads computed at each joint. In a second separate file with the same frame model, I apply the lateral loads from the first file combining them with the gravity loads and perform the analysis. I consider this procedure of mine very tedious in case of a 3D high rise building most specifically in view of the first file. Is there any shorter procedure for this? Please take note that I am using the Command File Editor.
5. I am trying to analyse a structure which consists of a large dia pipe supported at discrete points. I am unable to get STAAD to analyse this for UBC loads.
6. I am modelling a steel building consisting of columns and beams. The floor slab is a non-structural entity which, though capable of carrying the loads acting on itself, is not meant to be an integral part of the framing system. It merely transmits the load to the beam-column grid.  There are uniform area loads on the floor (think of the load as wooden pallets supporting boxes of paper). Since the slab is not part of the structural model, is there a way to tell the program to transmit the load to the beams without manually figuring out the beam loads on my own?
7. When does one use FLOOR LOAD and when does one use ELEMENT LOAD?
8. What is the difference between the LOAD COMB & REPEAT LOAD commands?
9. I am modelling an elevated silo which will be used for storing grain. The columns which support the structure are modelled as members and the walls of the silo (containment part of the structure) are modelled using plate elements. The silo has vertical and sloping walls. The loads on the structure consist of the weight of the grain contained in the silo. What is the best method for applying the load when the silo is full of grain? As pressure loads on the inside? How should the load be applied on the sloping walls?
10. I modeled a curved beam using cylindrical coordinates and tried to run a moving load over the curved beam. STAAD.Pro is not allowing me to do this. Why?
11. What is the significance of the Rw Value in the UBC code?
12. How is the wind load calculated/generated for a structure in STAAD.Pro ? What is the exposure factor calculated and how is it calculated? In 2002, I hear you can now define your own "panels"? What does this mean?
13. I am using the moving load generation. The truck that I am specifying is so wide (dimension perpendicular to direction of traffic) that within the width of one lane of traffic, there are 3 or more parallel beams along the direction of traffic. How does STAAD determine how the truck load should be converted to beam loads?
14. For moving load generation, does STAAD provide the location of all the moving point loads in terms of member number and distance from the start of the member?
15. How does STAAD consider the moving load over the beams if the load is not applied over a beam exactly?
16. If we have a wind load on a bracing system (perpendicular to the bracing plane), can we apply the wind loading directly to the brace as a uniform load instead of resolving the force into point loads? How does Staad handle this type of loading on members that are declared trusses?
17. I am using the moving load generation facility to generate a set of load cases for a truck moving on a bridge. Can STAAD provide the support reactions for the critical position that produces the maximum effects on the system flooring?
18. I have some distributed loads on some members of the model. I would like to consider the weights due to these loads in the base shear calculation for UBC load generation. Can you explain the process for doing this?
19. What is JOINT WEIGHT? I'm trying to learn how to use the seismic load generator and I don't see anything explaining what JOINT WEIGHT is or what it is used for.
20. How do I get STAAD to automatically combine static load cases with load cases generated using the MOVING LOAD generation facility?
21. How to calculate the temperature parameter f1 and f2  for applying temperature load on the
    structure?
22. I have multiple structures modeled in STAAD with varying heights and I want to use the Automatic Seismic Load Generation in STAAD. Can STAAD still properly distribute the seismic forces even though my structures are disjointed ?
23. I defined dead and live loads as reference load cases and I used these cases for specifying seismic weights as part of my seismic load definition. Do I have to re-define the dead loads and live loads as part of the seismic load case ?
24. Can STAAD automatically calculate the seismic forces both in horizontal and vertical direction required by ASCE as shown next E = (Rho) x QE (+/-) 0.2 x SDS x D
25. I am trying to generate moving loads but keep getting a message "Cannot create Load Generation command".
26. I can define Load Envelopes consisting of groups of loads and find that there are types like STRENGTH, SERVICEABILITY, COLUMN etc that I can choose from. What does these envelope types mean ?
27. I want to exclude some of my members from taking wind loading generated by STAAD. I cannot use the XR and YR to eliminate these members as there are other members within the same range that has to take up wind loading. Is there a way to do that ?
28. I am trying to analyze a staad.pro model with IBC loading and getting an error message  “*** STAAD.Pro ERROR MESSAGE *** NO LOADING DEFINED FOR UBC LOAD. RUN TERMINATED.”
29. [[**WARNING-A MOVING LOAD THAT WOULD HAVE BEEN APPLIED BEYOND THE X AND Z RANGES]]
30. [[Unit for Temperature Loading]]

1. Is it possible to specify a displacement and then have STAAD analyze a frame to give me a corresponding load (the load that would have been required to produce that displacement)?

You first need to know the pattern or arrangement of the loading which will eventually cause the displacement you wish to see. This is because, there can be millions of loading arrangements which cause that amount of displacement at that node, so one needs to have an idea of which of those patterns is the one that one wants. By pattern, we are talking of details like, is the load going to consist of concentrated forces at nodes, or distributed and trapezoidal loads on members, or pressures on plates, etc. For example, any of these loads will cause a certain amount of displacement at a node along a certain direction.

So, a unit load analysis would be the best approach for solving this kind of a problem. That means, all the components of the loading pattern would be represented by unit loads. Let us say that by applying a member load of 100 pounds/ft, you get 0.4 inches of displacement along global X at node 43. So, if the final desired displacement at node 43 along X is say, 1.2 inches, the applied load should be simply (1.2/0.4)*100 = 300 pounds/ft.

2. I am applying a UBC seismic load on a bridge. The analysis engine reports an error message which says that:

EITHER NA OR NV FACTOR HAS NOT BEEN SPECIFIED

WHILE SEISMIC ZONE HAS BEEN SPECIFIED AS 4.

This is due to the fact that, for your model, STAAD looks at the data under the DEFINE UBC LOAD command and concludes that you intend to analyse the structure per the UBC 1997 code. It then checks whether all the required parameters have been specified for that code, and detects that NA and NV are missing. You perhaps have an input similar to the one below :

DEFINE UBC LOAD
ZONE 0.4 I 1 RWX 12 RWZ 12 STYP 1.2 PX 0.2626 PZ 0.2626

For Zone 4, Na and Nv are two of the fundamental parameters necessary to calculate the base shear. If you look at Tables 16-Q and 16-R on pages 2-34 & 2-35 of the UBC 1997 code, you will find that for Zone 4, the coefficients Ca and Cv are dependent on Na and Nv.

So, specify the NA and NV parameters, so that the commands look similar to the one below :

DEFINE UBC LOAD
ZONE 0.4 I 1 RWX 12 RWZ 12 STYP 1.2 NA 1.6 NV 1.6 PX 0.2626 PZ 0.2626

3. I would like to create a REPEAT LOAD case whose constituent load cases are themselves REPEAT LOAD cases. Is this allowed?

You can do this if you have STAAD.Pro version 2002 or later. An example of this is shown below.

LOADING 1
SELFWEIGHT Y -1.0

LOAD 2
REPEAT LOAD
1 1.0
JOINT LOAD
4 5 FY -15. ; 11 FY -35.

LOAD 3
REPEAT LOAD
2 1.0
MEMB LOAD
8 TO 13 UNI Y -0.9 ; 6 UNI GY -1.2

LOAD 4
SELFWEIGHT Y -1.0
JOINT LOAD
4 5 FY -15. ; 11 FY -35.
MEMB LOAD
8 TO 13 UNI Y -0.9 ; 6 UNI GY -1.2

PERF ANALY
LOAD LIST 3 4
PRINT *** RES
FINISH

In the above example, load case 3 repeats load case 2, which in turn repeats load case 1.

4. After determining the lateral loads using Staad UBC seismic analysis in a first file, I note down the lateral loads computed at each joint. In a second separate file with the same frame model, I apply the lateral loads from the first file combining them with the gravity loads and perform the analysis. I consider this procedure of mine very tedious in case of a 3D high rise building most specifically in view of the first file. Is there any shorter procedure for this? Please take note that I am using the Command File Editor.

There is absolutely no need for you to take the lateral load data from the output of the first file, and insert it as input into the second file. In STAAD, once the lateral loads due to UBC or IBC are generated, they are automatically available for combining with gravity loads, or any other loads for that matter. Consequently, there are 2 ways in which this combination can be achieved, and each is demonstrated below :

Method 1 :
Generate the lateral load in one load case. Specify the gravity load in another load case. Then, combine the two in a load combination case.

LOAD 1 - GENERATE LATERAL LOADS DUE TO UBC ALONG X
UBC X 1.0

LOAD 2 - SPECIFY GRAVITY LOADS
SELFWEIGHT Y -1.0
MEMBER LOAD
1 TO 25 UNI GY -1.2
JOINT LOAD
10 39 FY -10.0

LOAD COMBINATION 3 - COMBINE THE LATERAL AND GRAVITY LOADS IN ONE CASE
1 1.0 2 1.0

Method 2 :
Create a single load case in which the lateral forces are generated, and gravity loads are specified.

LOAD 1 - LATERAL LOADS + GRAVITY LOADS
UBC X 1.0
SELFWEIGHT Y -1.0
MEMBER LOAD
1 TO 25 UNI GY -1.2
JOINT LOAD
10 39 FY -10.0

5. I am trying to analyse a structure which consists of a large dia pipe supported at discrete points. I am unable to get STAAD to analyse this for UBC loads.

When the UBC committee came up with the recommendations for analysing structures subjected to earthquakes, the type of structures they had in mind were conventional style buildings where the base of the model, namely, the points where the supports are located is at the lowest elevation with respect to the rest of the model.

If you look at the UBC procedure, it involves computation of the base shear, which then has to be distributed over the height of the building, so that one can then calculate the inter-story shears. A certain amount of the weight gets lumped at the highest point of the building, and the rest gets distributed along the height. In other words, the principle is that a mass at any height of the building is subjected to an acceleration and the force caused by the acceleration is represented by a concentrated force where the mass is located. The summation of all such forces at a given floor cause the columns beneath that floor to be subjected to a shear force.

When you talk of a model like a pipe which is defined as line members attached to several collinear nodes, all of which are at the same elevation, the UBC rules become impossible to apply. The fact is, to analyse your structure for seismic effects, you do not even need the elaborate procedure of the UBC code. You can take the selfweight, and any imposed loads on the pipe, and apply them along a horizontal direction like X or Z with a factor, and you will get what is normally expected in a seismic analysis.

So, you just have to have

LOAD 2
SELF X n

where n is a number like 1.5, which represents that there is a net force of 1.5 times the weight of the structure acting along the X direction due to an earthquake. For better handling of the distributed loads, you might want to consider defining several nodes along the length of the pipe, between supports.

6. I am modelling a steel building consisting of columns and beams. The floor slab is a non-structural entity which, though capable of carrying the loads acting on itself, is not meant to be an integral part of the framing system. It merely transmits the load to the beam-column grid.  There are uniform area loads on the floor (think of the load as wooden pallets supporting boxes of paper). Since the slab is not part of the structural model, is there a way to tell the program to transmit the load to the beams without manually figuring out the beam loads on my own?

STAAD's FLOOR LOAD option is ideally suited for such cases. This is a facility where you specify the load as a pressure, and the program converts the pressure to individual beam loads. Thus, the input required from the user is very simple - load intensity in the form of pressure, and the region of the structure in terms of X, Y and Z coordinates in space, of the area over which the pressure acts.

In the process of converting the pressure to beam loads, STAAD will consider the empty space between criss-crossing beams (in plan view) to be panels, similar to the squares of a chess board. The load on each panel is then tranferred to beams surrounding the panel, using a triangular or trapezoidal load distribution method.

Additional information on this facility is available in example problem 15 in the examples manual, and section 5.32.4 in the STAAD.Pro Technical Reference manual.

7. When does one use FLOOR LOAD and when does one use ELEMENT LOAD?

When modelling a grid system made up of horziontal beams and the slabs which span between the beams, we have found that there are 2 approaches that users take :

1) They model the beams only, and do not include the slabs in the model. However, they take into account the large inplane stiffness of the slab by using the master-slave relationship to tie together the nodes of the deck so that a rigid diaphragm effect is simulated for the horizontal plane at the slab level.

2) They model the slabs along with the beams. The slabs are modelled using plate elements.

The question that arises is, how does one account for the distributed loading (load per area of floor) which is present on top of the slab?

If you model the structure using method (1), the load can be assumed to be transferred directly on to the beams. The slab-beam grillage is assumed to be made up of a number of panels, similar to the squares of a chess board. The load on each panel is then tranferred to beams surrounding the panel, using a triangular or trapezoidal load distribution method. You can do this in STAAD by defining the load intensity in the FLOOR LOAD command. In other words, the pressure load on the slabs (which are not included in the model) are converted to individual beam loads by utilizing the FLOOR LOAD facility.

In method (2), the fact that the slab is part of the model makes it very easy to handle the load. The load can be applied on individual elements using the ELEMENT LOAD facility. The connectivity between the beams and elements ensures that the load will flow from the plates to the beams through the columns to the supports.

8. What is the difference between the LOAD COMB & REPEAT LOAD commands?

The difference lies in the way STAAD goes about calculating the results - joint displacements, member forces and support reactions. For a load combination case, STAAD simply ALGEBRAICALLY COMBINES THE RESULTS of the component cases after factoring them. In other words, for example, in order to obtain the results of load 10, it has no need to know what exactly is it that constitutes load cases 3, 4 and 5. It just needs to know what the results of those cases are. Thus, the structure is NOT actually analysed for a combination load case. With a REPEAT LOAD case however, the procedure followed is that which occurs for any other primary load case. A load vector {P} is first created, and later, that load vector gets pre-multiplied by the inverted stiffness matrix.

9. I am modelling an elevated silo which will be used for storing grain. The columns which support the structure are modelled as members and the walls of the silo (containment part of the structure) are modelled using plate elements. The silo has vertical and sloping walls. The loads on the structure consist of the weight of the grain contained in the silo. What is the best method for applying the load when the silo is full of grain? As pressure loads on the inside? How should the load be applied on the sloping walls?

There are 2 segments of the tank which have to be individually considered for application of the load.

The vertical walls
------------------

The material in the tank, especially if it is a fluid, will exert a lateral pressure on the vertical walls of the tank. This pressure load can be applied on the tank using the ELEMENT PRESSURE load facility. You can use one of 2 options to do this.

a) A uniform pressure. If you take any individual element on the wall, if you know the pressure intensity at the top edge, and the pressure intensity at the bottom edge, the average of these 2 intensities can be applied as a constant pressure on the entire surface of the element, as in the following example :

45 PRESSURE -3.5

Since the load is along the local Z axis of the element, you do not have to specify the axis name in the above command since local Z is the default for the axis. The load value must be accompanied by the proper sign (positive or negative) which accounts for whether the load acts along or opposite to the direction of the local Z axis.

b) A trapezoidally varying pressure.

In case (a) above, we decided to take the average of the pressures at the top and bottom edges, and thus obtain a uniform pressure. However, this is not absolutely necessary. The load can be applied as a trapezoidal load, in which case, the TRAP option is used and the intensities at the top and bottom edges must be specified. An example of that is

45 PRESSURE TRAP Y -4.5 -2.5

In this example, it is assumed that the local Y axis of element 45 is along the vertical direction, and thus the trapezoidal variation is along the local Y. The load itself acts perpendicular to the surface of the element, and hence along local Z. If local Y is in the same sense as global Y, -4.5 indicates the intensity at the lower edge, and -2.5 indicates the intensity at the upper edge.

If the vertical wall has many divisions along the vertical direction, there will be several "horizontal rings" of elements. Every element contained in a ring has the same intensity at its top and bottom edge. That means, the top & bottom intensity for each of those rings will have to be manually calculated. There is a facility in the STAAD.Pro GUI to simplify this task. From the top of the screen, select Commands - Loading - Load Commands - Element - Hydrostatic Trapezoidal, and provide the intensities at the top and bottom edges of the vertical wall. The program will use the linear interpolation method to find the intensity at each intermediate division, and then create the individual element TRAPEZOIDAL loads.

The sloping walls
-----------------

The load on the elements which make up these walls is derived from the weight of the column of material directly above these elements, and acts along the global vertical downward direction. Since the element TRAP load facility that is available in STAAD allows a load to be applied only along the local Z axis, and since local Z is not parallel to any of the global directions, the TRAP load option cannot be used here. Hence, one will have to apply these as uniform pressure loads, the value of which has to be calculated for each sloping element as the average of the intensities at the 4 nodes of that element. There is no generation facility currently available in the program to automate this task.

10. I modeled a curved beam using cylindrical coordinates and tried to run a moving load over the curved beam. STAAD.Pro is not allowing me to do this. Why?

Moving load on curved beams is not supported by the DEFINE MOVING LOAD command in STAAD.Pro. The STAAD moving load generator assumes:
1)All loads are acting in the negative global vertical (Y or Z) direction. The user is advised to set up the structure model accordingly.
2)Resultant direction of movement is determined from the X, Y and Z increments of movements as provided by the user.

However, STAAD.beava, an automated bridge load generator, can handle moving loads for curved or custom-defined bridge decks with beams and plates. It also generates a 3D influence surface based on displacements, support reactions, beam forces or plate stresses for any point on the bridge. The critical loading patterns and critical vehicle position will be identified as well. STAAD.beava is an integrated module in the STAAD.Pro environment.

11. What is the significance of the Rw Value in the UBC code?

The UBC 1997 code defines Rw as a Numerical Coefficient representative of the inherent overstrength and global ductility capacity of lateral-force resisting systems.

It is to be used in the equation for computing base shear. Its values are dependent on the type of lateral-force resisting system in the building, such as whether the system is a Light-framed wall with shear panels or Shear wall made of concrete or a special moment resisting frame, etc.

Values of Rw are listed in Tables 16-N and 16-P of the UBC 1994 and 1997 codes.

12. How is the wind load calculated/generated for a structure in STAAD.Pro ? What is the exposure factor calculated and how is it calculated? In 2002, I hear you can now define your own "panels"? What does this mean?

The DEFINE WIND LOAD command may be used to define the parameters for automatic generation of wind loads on the structure. The user needs to define the intensity and corresponding heights along with the exposure factors. If the exposure factor is not defined, the program takes the default value as 1.0.

A value of 1.0 means that the wind force may be applied on the full influence area associated with the joints if they are also exposed to the wind load direction.
All loads and heights are in the current unit system. In the list of intensities, the first value of intensity (p1) acts from the ground level up to the first height. The second intensity (p2) acts in the global vertical direction between the first two heights (h1 and h2) and so on. The program assumes that the ground level has the lowest global vertical coordinate of any joint entered for the structure.

The exposure factor (e) is the fraction of the influence area associated with the joint(s) on which the load may act if it is also exposed to the wind load. Total load on a particular joint is calculated as follows.

JOINT LOAD = (Exposure Factor) x (Influence Area) x (Wind Intensity).

Exposure factor (User specified) = (Fraction of Influence Area) x (influence width for joint).

In STAAD.Pro 2002, the built-in wind load generation facility has been enhanced to allow the user to specify the actual panels of the building which are exposed to the wind. This user-level control will now allow the user to obtain a more accurate distribution of wind forces, especially when the exposed surface of the building lies in several vertical zones, each reset from the one below or the one above, in terms of the direction of wind force. Further, the basic algorithm for detecting the shape of the panels and the amount of load which should be calculated for the panel corners too has undergone significant improvements. The parameters for definition of the wind load types are described in Section 5.31.3 of the STAAD.PRO Technical Reference Manual. The relevant extracts from Section 5.32.12 of the STAAD.Pro Technical Reference Manual, where the method for applying wind loading in the form of a data in load cases has been explained, is provided below. Note that areas bounded by beam members (and ground), and exposed to the wind, are used to define loaded areas (plates and solids are ignored). The loads generated are applied only at the joints at vertices of the bounded areas. For example, in the following set of commands:

DEFINE WIND LOAD
TYPE 1
INTENSITY 0.1 0.12 HEIGHT 100 200
EXP 0.6 JOI 1 TO 25 BY 7 29 TO 37 BY 4 22 23
TYPE 2
INT 0.1 0.12 HEIGHT 100 900
EXP 0.3 YR 0 500
LOAD 1
SELF Y -1.0
LOAD 2
WIND LOAD Z 1.2 TYPE 2 ZR 10 11
LOAD 3
WIND LOAD X TYPE 1 XR 7 8

A minus sign indicates that suction occurs on the other side of the selected structure. If all of the members are selected and X (or Z) is used and the factor is positive, then the exposed surfaces facing in the -x (or -z) direction will be loaded in the positive x (or z) direction (normal wind in positive direction). If X and a negative factor is used, then the exposed surfaces facing in the +x direction will be loaded in the negative x direction (normal wind in negative direction). [If -X is entered and a negative factor, then the exposed surfaces facing in the -x direction will be loaded in the negative x direction (suction). If -X is entered and a positive factor, then the exposed surfaces facing in the +x direction will be loaded in the positive x direction (suction).] A member list or a range of coordinate values (in global system) may be used. All members which have both end coordinates within the range are assumed to be candidates for defining a surface which may be loaded if the surface is exposed to the wind. The loading will be in the form of joint loads (not member loads). 1, 2 or 3 ranges can be entered to form a "layer", "tube" or "box" for selecting members in the combined ranges. Use ranges to speed up the calculations on larger models.

It is advisable not to use the SET Z UP command in a model with wind load. A closed surface is generated by the program based on the members in the ranges above and their end joints. The area within this closed surface is determined and the share of this area (influence area) for each node in the list is then calculated. The individual bounded areas must be planar surfaces, to a close tolerance, or they will not be loaded. Hence, one should make sure that the members/joints that are exposed to the wind make up a closed surface (ground may form an edge of the closed surface). Without a proper closed surface, the area calculated for the region may be indeterminate and the joint force values may be erroneous. Consequently, the number of exposed joints should be at least 3.

13. I am using the moving load generation. The truck that I am specifying is so wide (dimension perpendicular to direction of traffic) that within the width of one lane of traffic, there are 3 or more parallel beams along the direction of traffic. How does STAAD determine how the truck load should be converted to beam loads?

Based on the data you provide under the DEFINE MOVING LOAD command, each truck is treated as a set of axles. If the WIDTH option is NOT specified, each axle is assumed to be comprised of 1 tire. If the WIDTH option is specified, each axle is assumed to be comprised of 2 tires.

The program looks at each tire independently. For any given tire, it looks for one longitudinal beam to the left of the tire, and another longitudinal beam to the right of the tire. Then it distributes the tire weight on those 2 beams as though the tire is located on a simply supported cross beam that spans the two longitudinal members on either side.

Thus, even if a lane spans across 3 longitudinal beams or for that matter several beams, the above approach ensures that the tire weights get properly applied on the correct set of beams as concentrated member loads.

You can get a listing of these concentrated member loads by using the command:
PERFORM ANALYSIS PRINT LOAD DATA

14. For moving load generation, does STAAD provide the location of all the moving point loads in terms of member number and distance from the start of the member?

Yes. Please use the PRINT LOAD DATA option with your PERFORM ANALYSIS command and you will get the information in your output file.

15. How does STAAD consider the moving load over the beams if the load is not applied over a beam exactly?

If a wheel falls inside a panel composed of beams on either side of the wheel running parallel to the direction of movement of the vehicle, the load is distributed on the 2 beams as simply supported reactions. Hence, if the wheel load is 10 kips, and if the distance from the wheel to the beam on the left is 7 ft, and the distance to the beam on the right is 3 ft, the beam on the left gets a 3 kip load, and the beam on the right gets a 7 kip load.

16. If we have a wind load on a bracing system (perpendicular to the bracing plane), can we apply the wind loading directly to the brace as a uniform load instead of resolving the force into point loads? How does Staad handle this type of loading on members that are declared trusses?

If a transverse load such as a uniform distributed load or a concentrated force is applied on a truss member, STAAD converts it to the equivalent concentrated shears at the 2 ends of the member. The member end force output will show them as shears on the member under the output terms SHEAR-Y or SHEAR-Z depending on the local axis direction the load is applied in.

However, if you determine the equivalent end shears and apply them as joint loads instead, and not as a member load, the truss members at that node will not experience any shear force due to that load.

17. I am using the moving load generation facility to generate a set of load cases for a truck moving on a bridge. Can STAAD provide the support reactions for the critical position that produces the maximum effects on the system flooring?

This would require that the support reactions for all generated load cases be produced in a report form sorted in a descending order based upon the specific support reaction criteria we are interested in, such as the FY force, or the MZ moment.

To get this report, first run the analysis. Go to the Post processing mode. Select the support node(s) at which you want the information you are seeking. From the top of the screen, select Report | Support Reactions. In the dialog box that comes up, select the degree of freedom (FY, MZ, etc.) which should be used as the criteria for sorting. Set the sorting order (high to low or low to high). From the loading tab, select the load cases that you want considered. Click on OK. A report of the results will be displayed in tabular form.

18. I have some distributed loads on some members of the model. I would like to consider the weights due to these loads in the base shear calculation for UBC load generation. Can you explain the process for doing this?

When analysing a structure for UBC loads, there 2 stages in the input. The first stage is the one where one defines data such as the various parameters (zone factor, importance factor, soil structure interaction factor, etc.) as well as the weights. In terms of the STAAD command language, it is initiated using the DEFINE UBC LOAD command, and an example for this may be found in Example 14 of the STAAD.Pro Examples manual.

Graphically, one may assign the data in the following manner.

Select the beam or beams you want to assign the distributed weights to. Next, from the top of the screen, select Commands | Loading | Define Load | Seismic Load. In the Parameters tab, select the type, and enter the relevant
values for the parameters. Press the "Save" button. A new tab called "Weights" should come up. Press the "Member Weight" button. For the loading type, choose UNI, enter the distributed weight value, distances to where the load starts and the load ends, and press "OK". Press the "Assign" button to actually assign them to the selected members. Finally, press the "Close" button.

19. What is JOINT WEIGHT? I'm trying to learn how to use the seismic load generator and I don't see anything explaining what JOINT WEIGHT is or what it is used for.

In the block of commands which fall under the DEFINE UBC LOAD heading or any of the other ones like AIJ ,1893, etc., the weight data which goes into the calculation of the total seismic weight consists of :

SELFWEIGHT

JOINT WEIGHT

MEMBER WEIGHT

FLOOR WEIGHT

...

If at any of the joints of the structure, there are any weights which you want included in the total seismic weight calculation, you specify them using the JOINT WEIGHT option. These loads could be dead loads, imposed loads or live loads. Eventually these all these weights mentioned above are added together to arrive at the total seismic weight (W) which is then multiplied by the coefficient ( Cs or equivalent which is calculated by the software ) to arrive at the base shear value.

20. How do I get STAAD to automatically combine static load cases with load cases generated using the MOVING LOAD generation facility?

You should use the option called ADD LOAD along with the LOAD GENERATION command.

Shown below is an example:

DEFINE MOVING LOAD
TYPE 1 LOAD 20. 20. 10. DISTANCE 10. 5. WIDTH 10.
LOAD 1 STATIC LOAD
SELF Y -1.0

* GENERATE MOVING LOADS AND ADD THE SELFWEIGHT
* LOAD TO EACH GENERATED LOAD CASE

LOAD GENERATION 10 ADD LOAD 1
TYPE 1 7.5 0. 0. ZI 10.
PERFORM ANALYSIS PRINT LOAD DATA

21. How to calculate the temperature parameter f1 and f2  for applying temperature load on the
structure?

You have to know three temperatures :
 
1) the stress-free temperature, which is the temperature that the structure was at when it was constructed or installed.  Call it A.
 
2) The temperature of the top fiber (the fiber that is farthest along the positive direction of the local Z axis of elements and local Y axis for beam). Call it B.
 
3) The temperature of the bottom fiber (the fiber that is farthest along the negative direction of the local Z axis of element and local Y axis for beam). Call it C.
 
When you specify the temperature load, the command is
member-list TEMPERATURE f1 f2
where
 
f1 = (B+C)/2 - A
 
f2 = B-C
 
f1 is the temperature that causes axial elongation / shrinkage along the longitudinal axis (local X of the member, and, local X and Y axes for the plate element).
 
 f2 is the temperature responsible for inducing bending in the member and element.
 
Also, refer to article 5.32.6 of the Technical Reference Manual of Staad.pro

22. I have multiple structures modeled in STAAD with varying heights and I want to use the Automatic Seismic Load Generation in STAAD. Can STAAD still properly distribute the seismic forces even though my structures are disjointed ?

STAAD.Pro Seismic Load Generation should not be used in this case. If the structures are independent of each other, you should have 3 separate models and do seismic load generation on each model separately.

23. I defined dead and live loads as reference load cases and I used these cases for specifying seismic weights as part of my seismic load definition. Do I have to re-define the dead loads and live loads as part of the seismic load case ?

Related question : I defined dead loads, live loads for seismic weight calculation as part of my seismic load definition. Do I again need to specify the dead and live loads as part of the seismic load cases ?

No you do not need to. Once the seismic weight is defined ( either through reference load or through the various seismic weight definition options ) as part of the seismic load definition, the software is able to figure out the total seismic weight. You do not need to redefine. Doing so would apply these as additional loads to the ones already defined. 

24. Can STAAD automatically calculate the seismic forces both in horizontal and vertical direction required by ASCE as shown next 

E = (Rho) x Q_E (+/-) 0.2 x S_DS x D

As per section 12.4.2 of ASCE 7-10,

E = E_h + E_v

and

E = E_h– E_v

where

E_h = ρ * Q_E (equation 12.4-3 of ASCE 7-10) is the Horizontal seismic load effect

and

E_v =  0.2 * S_DS * D  is the vertical seismic load effect described in equation 12.4-4

STAAD calculates only the Q_E term of the horizontal component E_h. The user has to manually multiply Q_E by ρ to obtain E_h. There is no provision in STAAD to input ρ, which is defined in section 12.3.4.2 as a redundancy factor for Seismic Design categories D through F.

STAAD does not calculate the vertical component E_v. However, the user can indirectly get the program to perform this calculation by applying all the loads that come under the category of “D” (Dead Load) along the global Y direction with a factor of 0.2 * S_DS. For example, if S_DS is 0.18, and the only load item that constitutes dead load is the selfweight, then, E_v can be obtained by specifying the following load case

SELFWEIGHT Y 0.036 

25. I am trying to generate moving loads but keep getting a message "Cannot create Load Generation command".

Most likely you have LOAD COMBINATIONS already defined as part of the file and there is not enough gap in numbering between the last primary load case and the load combination to accomodate the number of moving load generations that has been asked for. For example if you have 

LOAD 1 DEAD LOAD
SELF Y -1.0
*
LOAD 2 LIVE LOAD
MEMBER LOAD
100 TO 150 UNI GY -1
*
LOAD COMB 3 DEAD + LIVE
1 1.0 2 1.0

then if you try to generate 30 moving load cases as shown next

LOAD GENERATION 30
TYPE 10 12 1 0 ZINC 1

Here are a couple of options to handle this scenario.

Change the LOAD COMBINATION number to anything higher than 32 to accomodate 30 generations after load case 2. Remember these generations are all treated as primary load cases by STAAD and so has to come shead of the combinations.

Alternately you may change the LOAD COMBINATION to REPEAT LOAD as shown next

LOAD 3 DEAD + LIVE
REPEAT LOAD
1 1.0 2 1.0

REPEAT LOADs are considered as primary load case by STAAD.Pro and hence you would be able to generate the moving load generations after that without any problem.

26. I can define Load Envelopes consisting of groups of loads and find that there are types like STRENGTH, SERVICEABILITY, COLUMN etc that I can choose from. What does these envelope types mean ?

The type for the envelopes are supposed to indicate what the envelope ( which is essentially a cluster of loads ) is meant to be used for. For example if the type is specified as Serviceability it would be used for serviceability checks like deflection check. STRENGTH envelope means the component loads would be used for member strength check. However as of now, all design codes in STAAD.Pro are not equipped to honor the envelope types. The latest
AISC 360 10 code check is able to do appropriate code checking based on envelope specifications SERVICEABILITY and STRENGTH. As far as the other envelope types are concerned, COLUMN was developed based on requirement obtained from a particular company who wanted to tag all the load cases for column design separately and type Connection was defined to tag all load cases to be used for connection design.

27. I want to exclude some of my members from taking wind loading generated by STAAD. I cannot use the XR and YR to eliminate these members as there are other members within the same range that has to take up wind loading. Is there a way to do that ?

Often one may need to apply wind loading on a specific set of members in a model. For example one may have cross braces in a vertical plane and may have wind load acting normal to the plane of these braces, which one may not want the braces to take. In such situations, one may define a group consisting of members which are expected to take the wind load and apply the
wind loading on these groups as shown next. As of now the data has to be entered using the editor as there are no options in the GUI for doing this

In the above example, wind loading type 2 and 4 has been applied on two separate member groups _X_AT_WEST and _X_AT_EAST respectively.

28. I am trying to analyze a staad.pro model with IBC loading and getting an error message  “*** STAAD.Pro ERROR MESSAGE *** NO LOADING DEFINED FOR UBC LOAD. RUN TERMINATED.”

Although the error message says UBC but it is a generic message that is applicable to seismic load generations as per all other codes as well, including IBC.

The reason for getting the error is that, no seismic weight has been specified as part of the seismic definition and hence Staad is unable to calculate the Base Shear ( V = Cs x W ). As part of the seismic definition you need to specify various seismic parameters like Ss, S1, TL, I , SITE CLASS etc which are used to compute the coefficient Cs. In addition you need to define the seismic weights which will be used by the software to calculate the W term in the base shear equation. One can specify seismic weights in the form of selfweight , member weight , joint weight , element weight etc for. A sample input is provided below

DEFINE IBC 2006
SS 2.16 S1 0.80585 I 1 RX 3 RZ 4 SCLASS 4 TL 12
SELFWEIGHT 1
JOINT WEIGHT
50 51 54 55 WEIGHT 2
MEMBER WEIGHT
125 TO 127 UNI 1

An example problem EXAMP14.std is included with the software to explain the seismic load generation.

29. I am trying to analyze a staad.pro model with IBC loading and getting an error message  “*** STAAD.Pro ERROR MESSAGE *** NO LOADING DEFINED FOR UBC LOAD. RUN TERMINATED.”

Your floor group consists of multiple panels which are not lying on the same plane. This necessarily needs to be lying on a single plane.

See Also

Product TechNotes and FAQs

Structural Product TechNotes And FAQs

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please confine any comments you have on this Wiki entry to this "Comments or Corrections?" section. THANK YOU!

Problem Description

Note: This issue has been resolved in the updated version, v17.02.00.130 Installing this version should prevent the problem.

* The exact version where the issue started is unknown, but it may go back as far as version 17.00.00.49.

When a designed and saved model is re-opened, the program recalculates the beta angle of the resultant horizontal section cut forces. These global forces were not converted to the local axes of the wall prior to the calculation of the beta angle.
Effect: An incorrect beta angle was calculated and displayed for the resultant forces on walls at any orientation other than 0 degrees. Generally, this was only a display error. However, subsequent optimizations may have been based on calculations using this erroneous beta angle, resulting in incorrect designs. 

Here is an example of a skewed wall with major and minor axis moments. The beta angle below are the initial values used, based on the local axis of the section. Note that the angles are about 30 degree off the 0 or 180 degree axis:

When the same wall is reviewed in s later session without performing analysis the values are off: 

Solution

Update to version 17.02.00.130.

Where that is not possible, only use or print the results from Concrete Shear Wall Design immediately after running Ram Frame analysis.  

Problem Description

When attempting to perform a floor vibration analysis, the following error occurs after the FloorVibe window opens:

File/path access error.

Reason

FloorVibe attempts to write files to the FloorVibe folder in Program Files or Programs Files (x86).

Under Windows Vista or later, these files are normally redirected to a VirtualStore folder stored in the user's profile, for example:

C:\Users\Seth.Guthrie\AppData\Local\VirtualStore\Program Files (x86)\Bentley\Engineering\RAM Structural System\Prog\FloorVibe

If the redirection is disabled, the program will fail to successfully write the file unless the permissions are adjusted on the FloorVibe folder.

Steps to Resolve

Ensure the user has modify permissions to the FloorVibe folder located in either Program Files or Program Files (x86).

Some users with historical versions of Ram Structural System (e.g. 14.06 or earlier) and FloorVibe (e.g. 2.02 or earlier) may still have a residual Structural Engineers folder in the Program Files location. Uninstalling the older FloorVibe application and then reinstalling RAM Structural System 14.07 or later is advised in that case.

See Also

[[RAMSS FloorVibe FAQ]]

[[SELECTsupport TechNotes And FAQs]]

Error or Warning Message

When attempting to perform floor vibration analysis from the Steel Beam module, the following error appears:

Please specify the location of the FloorVibe.exe program using the following dialog.","FloorVibe location?

If canceled, the following error occurs:

FloorVibe program not found. Please verify that it is properly installed.

Explanation

FloorVibe is a third-party product developed by Dr. Murray of Structural Engineers, Inc. A link has been developed between the Steel Beam module in RAM Structural System and FloorVibe. Although FloorVibe integrates with RAM Structural System, it is installed separately. The two error messages occur when FloorVibe is not installed on a workstation.

Starting with RAM Structural System V14.07 the program will now be installing the latest version of both FloorVibe (V2.20, based on Design Guide 11) and FloorVibeUK (V1.02, based on SCI Publication P354), so all clients will get the latest of both.

How to Avoid

Install FloorVibe on the workstation. Based on a third-party agreement, users in the United States and the United Kingdom are provided with a copy of the FloorVibe installer through Bentley when a perpetual license for RAM Steel is originally purchased. Users in other countries can purchase FloorVibe directly from Dr. Murray by visiting http://www.floorvibe.com/.

Users who cannot locate a FloorVibe installer should contact technical support via the forums or SELECTsupport to obtain another copy of the installer. FloorVibe is distributed as a zip archive. To install the product, please expand the zip archive, and run Setup.exe. To avoid installation issues, do not run FloorVibe.msi or FloorVibeUK.msi directly. Regretfully we can no longer send the very latest version of FloorVibe. If you need to user version 2.10 or later, visit http://www.floorvibe.com/.

See Also

[[RAMSS FloorVibe FAQ]]

[[SELECTsupport TechNotes and FAQs]]

Problem Description

In Ram Elements it is possible through spreadsheet data entry to create an incomplete or zero length object. For example, if you add a member and enter the NJ node, but never enter the NK node and move on, that member is still in the database, but it has an undefined geometry. 

The same kind of thing can also happen with a shell or deck (load area).

It's also possible to create a member that has no length by defining it between two nodes that are on top of eachother. To purge the model of duplicate nodes use Process - Puge and Reconnect Model. 

In order for the program to function, any such member either needs to be completed with valid incidence or deleted from the model.

Solution

The key to resolving the problem is selecting the problem member. Since it has no graphics it cannot be selected with the mouse, so the user needs to use Select All (Ctrl + A) or one of the other selection tools like Select - Members - Select all members first.

If any part of the model is hidden, be sure to Unhide (Ctrl +H) first, then Select All.

At that point the item will appear again in the spreadsheet so that the missing data can be added. If the intent is to delete the problem member, first select all to identify it's unique number. Now remember that number or write it down and clear the selection (one click in space will do). Next enter that number in the first row, first column of the appropriate spreadsheet and then only that one object is selected.

To delete it:

• Right click in the spreadsheet and choose Clear,
• Right click on the graphics window and choose Delete, or
• Press the delete key.

Note, you cannot be in the Finite Element View mode when deleting data. 

See Also

Ram Elements Modeling [FAQ}

Why are the column reactions in the Lateral loads so small?

In Ram Structural System 14.07 a change was made in the behavior of 2-way slabs under lateral loads. To prevent the slab from coupling lateral walls and columns together the out-of-plane stiffness is ignored in those lateral load cases when the diaphragm is set to rigid. With the out-of-plane stiffness near zero, the unbalanced forces in lateral columns above and below the slab are necessarily tiny.

Solution

In order to have the out of plane stiffness considered under lateral loads the diaphragm at the level being exported to Ram Concept must be set to semi-rigid. 

See Also

RAM Concept Lateral Self Equilibrium Analysis [TN]

RAMSS Two Way Decks

RAM Frame - Criteria - Diaphragms

In this page, all the past and upcoming structural events in Middle East region are listed. 

In 2020, Bentley Structural team has delivered several webinars on STAAD.Pro CONNECT Edition. These webinars were delivered not only to demonstrate the advanced features and new enhancements of new and updated CONNECT Edition version, but also covered several structural discussions like stability analysis, seismic analysis and more.

Following are the list of all these structural events. You can go through the recorded session anytime by registering using the link mentioned below. If you have already registered, then you can directly login using the joining link sent to you earlier to your registered email ID. Note that, we monitor the sessions regularly and if you have any technical doubts, you can let us know using the Q&A console. We will get back to you via email.

Example on Direct analysis with steel design as per AISC 360-10 using STAAD.Pro

The attached example has been created to give users an idea on how to carry out Direct Analysis on a steel structure using STAAD.Pro and also how to set up the strength and serviceability envelopes and eventually carry out a steel design as per the ASIC 360-10 specification following the LRFD design approach. This is just a sample problem with a limited set of load cases mainly aimed at demonstrating how one should set up the Direct Analysis and the subsequent design process.

communities.bentley.com/.../Direct_5F00_Analysis_5F00_with_5F00_Steel_5F00_Design_5F00_Rev.std

What's the difference between ELASTIC MAT and PLATE MAT for spring support generation?

With the ELASTIC MAT you enter a list of joints from which STAAD will attempt to form a perimeter which encloses an overall area. This is done with a convex hull algorithm. Lastly, areas are assigned to each joint. If the convex hull rules are met, the algorithm works well. However for mats with irregular edges or holes, the algorithm may not do what the user expects and one may end up with springs with unreasonable spring constant values.

Since many mat foundation problems have plates defining the entire mat, we have added the PLATE MAT option where you enter a list of plates that entirely define the mat. Roughly 1/4th of the area of each plate is assigned to each joint in the plate in the same manner as uniform pressure or self weight is distributed.

So if you have the foundation support entirely defined by plates, then use the PLATE MAT option. Otherwise use the ELASTIC MAT option. With this option please observe the rules listed in the Tech Ref Manual. Avoid having internal angles > 180 degrees between lines forming the ELASTIC MAT. You may have to subdivide the region into several sub-regions with several ELASTIC MAT commands. Add "PRINT" to the end of the command to see the areas assigned to each joint where a support is generated.

More information related to this topics can be found in these discussions.

https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/207796/staad---elastic-mat-and-plate-mat-example-applications/626809#626809

https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/23967/y-and-y-only-commands/56200#56200

https://communities.bentley.com/products/ram-staad/m/structural_analysis_and_design_gallery/253408

https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/83078/base-pressure-calculation/231842#231842

https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/79236/plate-mat-support/217960#217960

https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/29311/elastic-foundation-error-0550

Comprehensive analysis and design of moment frames using the Simpson Strong-Tie Yield-Link moment frame connection is now available in the RAM Structural System. This document describes the use of this feature.

Modeling

Create the model as customary for any project using steel moment frames.  When assigning preliminary lateral beam and columns sizes in RAM Modeler or in RAM Frame, it is important to keep in mind the following rules:

1. The connection is only valid for moment frames with I-shaped columns, oriented in their strong axis.
2. The beam flange thickness, t_f, must be at least 0.4”.

Criteria

In RAM Frame, specify the moment frame type – SMF, IMF, or MF – using the Criteria – Yield-Link command.

The connection properties are different for high seismic (inelastic) applications versus wind (elastic) and low seismic applications. Select the criteria that is appropriate for the moment frames.

Note that Yield-Link panel zone properties are built-in automatically and accounted for when Yield-Link is assigned as a moment connection. In the Criteria – General command, the option to Ignore Effects for Rigid End Zones should be selected.

Assign

In RAM Frame, assign the moment connection type using the Assign – Beams – Frame Beam Connection Types command.

Select the Yield-Link tab. The Yield-Link connection can be assigned to one or both ends of the beam; select the desired option. Generally, the Frame beams will have the Yield-Link connection on both ends, but in some cases it might be desired to pin one end of the beam and assign the Yield-Link moment connection on the other.

Link sizes can be assigned to the beam using a selected default size. If the Default option is used the program will automatically select the Yield-Link size. However, this command can also be used to assign explicit Yield-Link sizes to the beams by selecting the Use option and specifying the desired connection size from the list. The default Yield-Link size selected by the program won’t necessarily work, but is a good starting point; if it is determined that the size is inadequate, the Assign command can be used to assign a different size.

If default sizes aren’t working, explicit sizes can be selected using the Use option:

Or it may be easier to modify the Default sizes by selecting the Change Defaults button and specifying larger default sizes:

The connection and Yield-Link sizes can be assigned selectively with the Single or Fence command, or to all of the Frame beams with the All command.

The Yield-Link connection can be assigned to cantilever members when the cantilevers are modeled as Stub cantilevers. The Yield-Link connection is incompatible with cantilevers modeled as Extensions.

Once the beam ends have been assigned, RAM Frame will display the Yield-Link moment connection symbolically as shown:

The Yield-Link size assigned to a beam can be graphically viewed by invoking the Assign – Beams – Frame Beam Connection Types command; if the size is a user-specified size, the size will be listed with an asterisk.

Analysis

Perform the Analysis. When the Analysis is performed, the appropriate Yield-Link connection criteria properties are applied accordingly. Certain checks on sizes are performed to ensure compatible sizes are assigned to the frames. Beam flanges must be at least 0.4 in. thick. Some combinations of beam size, column size, and Yield-Link size are not permitted. The beam flange and column flange must be sufficiently wide for the Yield-Link connector. If either is insufficient, a warning will be given when the Analysis is performed. It will then be necessary to assign a wider beam or wider column (or use a smaller Yield-Link connector). In some cases, the Analysis will be terminated, in which case the condition must be resolved before continuing. In other cases the Analysis will proceed, but the engineer must remember to go back and resolve the warning conditions, or to make special accommodations for the configuration (which would involve coordinating with the engineers at Simpson Strong-Tie to verify that the condition is acceptable, or to design a custom connection).

The Member Forces report for beams has been enhanced to identify that it has a Yield-Link connection, along with information about the joint stiffness:

A new section has been added to the Frame Takeoff report to include the Yield-Link sizes and the weight of the plates in the connections:

Drift

Verify that the drifts do not exceed the drift limits given by the building code. The drift values can be obtained using the Process – Results – Drift command. Adjust the member sizes and Yield-Link sizes as necessary.

Steel – Standard Provisions

Go to the Steel – Standard Provisions mode to determine the adequacy of the members and connections according to the standard steel specifications (i.e., AISC 360, not AISC 341).

To investigate the adequacy of the member sizes, invoke the Process – Member Code Check command. Use the Process – Member View/Update command to investigate individual members. Resize any failing members as necessary.

The design moment and shear for the beams are taken at the face of the column. The unbraced length of the beam is measured from face of column to face of column.

The design moment and shear for the columns are taken at the face of the beam. The unbraced length (both x and y) is taken as the column height, not reduced by the beam depth.

To investigate the adequacy of the Yield-Link connections, invoke the Process – Joint Code Check command. Joints that are adequate will show a green sphere symbol, joints that are adequate but require stiffener plates will be shown with a blue plate symbol, joints that are adequate but require a web doubler plate will be shown with a blue sphere symbol, and joints that fail will be shown with a red sphere symbol.

Use the Process – Joint View/Update command to investigate individual joints.

The joint will fail if the maximum size of web plate and stiffeners are inadequate to make the joint work, but the most common cause of joint failure will be a Yield-Link connector with inadequate area:

It may be able to resolve this by assigning a larger Yield-Link size. However, in some cases it may be necessary to assign deeper beam sizes. With deeper beams the distance between the Yield-Link connectors above the top flange and below the bottom flange increase, so the axial load in the connectors decrease (Axial Force = Moment / Distance between connector centroids).

The Joint View/Update dialog allows you to investigate increasing the column size to eliminate web plates and stiffeners, and to investigate different connector sizes to eliminate Yield Link Axial Capacity failures.

Steel – Seismic Provisions

In the Steel – Seismic Provisions mode the seismic provision requirements for AISC 341-16 and AISC 341-10, for both ASD and LRFD, have been implemented for Yield- Link connections. Select one of those codes in the Criteria – Codes command.

The Yield-Link tab of the Criteria – Joints command has settings for how the bracing of the top and bottom flange of the beams is to be considered per AISC 341 Section 12.3.2(7), the shear plate grade and thickness and bolt information, and the intended detail for the web plates.

It is necessary to assign a frame type to each member, used by the program to determine which seismic provisions are pertinent. This is done using the Assign – Frame Type command. Select either Special Moment Resisting Frame (R=8), Intermediate Moment Resisting Frame (R=4.5), or Moment Resisting Frame with R=3 as appropriate. This assignment must be consistent with the methodology selected in the Criteria – Yield-Link command, as explained above. If the frame type is not consistent with the methodology, the members will be indicated as failing; the following error message will be given in the View/Update command:

The Frame Type assignment on each member can be displayed by selecting the Frame Type labels option on the Frame Beam and Frame Column tabs in the View – Members command.

Select the Process – Member Code Check command to have the code check performed on all of the members, and select the Process – Member View/Update command to select and view the results for an individual member. Modify the member sizes as necessary to eliminate the member design failures.

Select the Process – Joint Code Check command to have the code check performed on all of the joints, and select the Process – Joint View/Update command to select and view the results for an individual joint.

The plates, bolts, and welds for the Yield-Link connection are designed when the Joint Code Check is performed. The shear plate and bolt information can be viewed and modified using the Shear Plate Properties button on the Joint View/Update dialog:

The Seismic Provisions Member Code Check and Joint Code Check reports show the results of all the checks, including the design of the Yield-Link connection plates.

CAD Elevations, Schedules, and Details

CAD drawings can be generated using the File – Export Yield-Link DXF command in RAM Frame. The drawings include Frame elevations, joint details, and all the associated tables of Yield-Link sizes, shear plate, stiffener plate (if required), doubler plate (if required), connection bolts and connection welds.  The information presented can be used for pricing and detailing by the contractor.

Design Review

Note:  For new users of Yield-Link moment connection, Simpson Strong-Tie will provide assistance to review the design file.  Users should send their RAM model (e.g. “filename.rss” file), to Simpson Strong-Tie at yieldlink@strongtie.com.  A Simpson Strong-Tie representative will contact you within 48 hours to discuss your project.

Generation of wind loads on members

This document serves as tutorial to show the RAM Elements tool for wind loads generation on members (open structure).

1.1 Model data

Open the “45.00m-height electrical tower.retx” model. The structure is formed by A36 steel equal leg angles for all segments and elements in the tower. The configuration is typical for electrical transmission towers.

                                   3D model                                                                Lateral view

All support bases are assumed to be pinned for the four-legged tower.

Gravitational loads are assumed as follows:

• Self-weight
• Cable weight

Imposed load considered as dead loads:

• Cable tension

Live load:

• Cable assembly load

The referenced model has been created with the previous loads. This example is focused on assigning the wind loads using the wind loads generation tool for members.

Lateral loads to apply:

• Wind in the X global axis direction
• Wind in the Z global axis direction

The model already has several design and service load combinations based upon ASCE 7-16 code.

1.2 To create the wind definitions

1. The wind loads definition manager can be accessed from the Home tab, and Definitions > Wind.
2. A dialog window opens. In this dialog, press +New in the top left toolbar to create a new wind definition. Note that once a new item is created, it may be deleted and saved after modifying the values in the fields at the right part where wind load data is shown.
3. Create a new definition for wind load with the +X axis direction and setting the direction to 0 degrees in the dialog region for Members. Edit the rest of the information in the manager fields using the following data:

4. Enter the structure geometry in the Building geometry group of data, as follows:
   8. Length, 8.00 m.
   9. Width, 8.00 m.
   10. Meanroof height, 45.00 m.
   11. Ground level, 0.00 m.

5. Enter the wind parameters in the Parameters group, as follows (refer to notes at the end of this section for an explanation of each field):
   1. Basic wind speed, 120 km/h.
   2. Gust factor, 0.85.
   3. Enclosure category, Open.
   4. Elevation above sea level, 0.00 m.
   5. Exposure category, C.
   6. Directionality factor, 0.85.
   7. Wind direction, 0 degrees. This will coincide with the positive global X axis direction.

6. Enter the topographic parameters in the Topographic factor, Kzt group, as follows (refer to notes at the end of this section for an explanation of each field):
   1. Select User defined and enter Kzt equal to 1.0.

7. Enter data in the Aerodynamic shape factor group, as follows (refer to notes at the end of this section for an explanation of each field):
   1. Leave unchecked the User defined checkbox to let the program calculate the factor automatically.

1.3 To assign the wind loads

1. Select the load case for which the wind loads will be assigned.

2. Select the desired members to assign wind loads using the tool. For this example, select all the members in the tower model since the tool can assign wind loads at once for the whole selection for one wind direction.

3. Select the Members > Loadson members spreadsheet.

4. On the Spreadsheet ribbon tab, select the Assign wind loads tool in the Active spreadsheet tools group.

The dialog to assign Wind load on members opens.

5. Select the “+X (0 deg)” load definition and press OK.
6. To see a report of calculated wind loads for selected members before confirming the assigned values in the dialog press the Preview report button and a report window will be displayed.

7. Once the dialog is closed, the wind loads are added for the current load case for all the selected members.

Wind loads on horizontal members

Wind loads on vertical members

Wind loads on diagonal members

Wind loads on all tower loads

8. After the wind loads are assigned, it is possible to access a wind loads report for the selected members, by looking for the Output tab, in the Reports group, the Data button and search for ..

Then select the Wind loads option for a desired load condition:

RAM Structural System CONNECT Edition Version 17.02.01 SES Release Notes

Anticipated Release Date: February 2021

This document contains important information regarding changes to the RAM Structural System. It is important that all users are aware of these changes. Please distribute these Release Notes and make them available to all users of the RAM Structural System.

This is a minor release, correcting some issues that affected some users of v17.02. The Release Notes for that version contain important information not included here in these abbreviate Release Notes. They can be found at:

https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/52610/ram-ss-v17-02-release-notes

Installation Instructions:

If you have enabled the CONNECTION Client you will automatically be notified of the newest version and will be able to update through that service by simply selecting the update command. Otherwise, this version can be found on the Bentley Software Fulfilment web page by logging into CONNECT Center and selecting the Software Downloads icon. Search for “RAM Structural System” and select the latest version.

Security Risk Advisory:

Not applicable to this release. Every effort is made to ensure that there are no security risks in the software. There are no known security issues, no issues were addressed in this version.

New Features and Enhancements:

For details on these new features and enhancements, refer to the manual .pdf files available from the Help menu in each module or from the Manuals folder on your hard drive.

Yield-Link

The capability of analyzing and designing moment frames utilizing the Simpson Strong-Tie Yield-Link connection was implemented in v17.02. Some enhancements and corrections have been made to that implementation.

• When the beam or column flange width is inadequate for the width of the Yield_Link size, the previous version gave a warning message, but the message didn’t indicate whether the problem was the beam width or the column width (or both). The message has been enhanced to indicate whether the problem is with the beam width or column width, and it lists the width required to accommodate the assigned Yield-Link size.

• In the joint graphic in the Joint View/Update dialog in Steel – Standard Provisions mode, “Side A” and “Side B” labels were added to clarify which side of the column was which.

• An error in the calculation of the demand capacity ratio for the Buckling Restraint Plate Bolt, Vuy-bolt / RnVy, was corrected; the calculated ratio was double the actual demand capacity ratio. Joints that would have otherwise passed this check may have been reported as having failed.

• An error was corrected in the Joint View/Update dialog in Steel – Standard Provisions mode. The program did not recognize any selections made by the user for the Side B Yield-Link size (the program correctly recognized selections made by the user for the Side A Yield-Link size).

Diaphragm Forces Report

Three options are now available for the Diaphragm Forces Report: Resultants, At Discreet Points, and Resultants and At Discreet Points. The values at Discreet Points was added to the report in v17.02, but because of the length of report that resulted, it was decided that the user should be given the option of obtaining the short report with the Resultants or the longer report with the values at Discreet Points, or both.

Table Editor

The Table Editor (Tools – RAM Table Editor) in RAM Manager has been enhanced to allow Copy and Paste; values can be pasted into the fields, eliminating the need to edit the values one by one. To do this, select the Value heading to highlight the entire column of data, and then Copy that column using Ctrl-C, or paste in values using Ctrl-V. It has also been enhanced to include the capability of editing the Detailing values that were added to the ramaisc.tab Master table in v17.02.

Error Corrections:

Some program errors have been corrected for this version. Corrections made to graphics, reports, Modeler functions, program crashes, etc., that were considered minor are not listed here. The noteworthy error corrections are listed here in order to notify you that they have been corrected or to assist you in determining the impact of those errors on previous designs. These errors were generally obscure and uncommon, affecting only a very small percentage of models, or had no impact on the results. The errors, when they occurred, were generally quite obvious. However, if there is any question, it may be advisable to reanalyze previous models to determine the impact, if any. In each case the error only occurred for the precise conditions indicated. Those errors that may have resulted in un-conservative designs are shown with an asterisk. We know these errors are disruptive, we apologize for any inconvenience this may cause.

Steel Column

B1 AND B2 REFERENCES:  The references for the B1 and B2 equations shown in the report were incorrect for the AISC 360-10 and AISC 360-16 specifications.

Effect: Report error only. When designing per AISC 360-10 and AISC 360-16, the B1 and B2 equation references for columns encountering B1 or B2 errors were listing older specification references.

Concrete Column

ACI 318-14 LIMIT ON NET TENSILE STRAIN: V17.02 was enhanced to include the tension strain limit of 0.004 for members with low axial load according to ACI 318-11 Section 10.3.5. However, this requirement is not required in Chapter 10 (Columns) in ACI 318-14, and should not have been applied to columns when the Code selection was ACI 318-14.

Effect: The limit of 0.004 on the net tensile strain of the reinforcement for lightly loaded columns was enforced on columns under ACI 318-14 even though it is not required for that code.

ACI 318 MAGNIFICATION FACTOR EXCEEDS 1.4: Some columns in some models in v17.02 reported that the Magnification factor, delta, exceeds 1.4. Work on an enhancement to check and give this warning is currently being done for a future version, but was not intended to be in v17.02. However, the partially complete work caused this warning to incorrectly appear.

Effect: Erroneous message. This has been removed until the feature is complete in a future version.

ACI 318 EFFECTIVE LENGTH FACTOR FOR Pc CALCULATION: Starting with v17.01, the value of  k used in the calculation of Pc for sway members was limited to 1.0, but for nonsway members the calculated k from the nomograph was applied.

Effect: Effective length factor used in the calculation of Pc may have been different than 1.0. For consistency the value of k is now always set to 1.0 in the calculation of Pc.

Frame – Analysis

SLOPING COLUMN REACTION MOMENTS*: The reaction moments at foundation nodes were calculated and reported incorrectly for sloping columns. The Frame Reactions report and the Process – Results – Reactions command listed incorrect moments.

Effect: The reported and displayed reactions results for moments at the base were not correct at sloping column.

USER-DEFINED WIND LOAD ON SEMIRIGID DIAPHRAGM: If a user-defined wind load on a semirigid diaphragm included eccentricity, the program may have incorrectly calculated the wind forces projected onto semirigid diaphragm edges. This resulted in excess loads.

Effect: Excess wind loads may have been applied to semirigid diaphragms.

RIGID END ZONE INFORMATION IN BEAM MEMBER FORCE REPORT: When the option to Include Effects for Rigid End Zones was selected with a Reduction % specified, the Member Forces report listed the Reduction % incorrectly. It listed the value of (100% - Reduction %), rather than Reduction %.

Effect: Report error only, an erroneous rigid end zone reduction value was reported.

EUROCODE EN 1998-1:2004 SEISMIC AND RESPONSE SPECTRA: The Loads and Applied Forces report crashed if the model included Eurocode EN 1998-1:2004+A1:2013 seismic or response spectra load cases.

Effect: Report crash. Analysis results were valid.

Frame – Steel Standard Provisions

NOTE: The Joint Code Check command has been disabled for this version if the selected Code is AISC 360-05 ASD, AISC 360-10 ASD, or AISC 360-16 ASD. The program was using ASD load combination forces, but was using LRFD design checks, which was unconservative. The Joint Code Check reports showed that the checks were LRFD checks, so the error should have been obvious if the reports were carefully reviewed. If joint checks were performed in any version previously using AISC 360-05 ASD, AISC 360-10 ASD, or AISC 360-16 ASD, it may be advisable to recheck those joints using LRFD. The Joint Code Check command for ASD will be reactivated in a future release after the defect has been corrected. Note that the error only affected ASD, it did not affect LRFD design.

ISM

SHOW IN STRUCTURAL SYNCHRONIZER: In the File – ISM – ISM Options command the selection of the option Show in Structural Synchronizer wasn’t respected, the Structural Synchronizer always launched.

Effect: Nuisance. User couldn’t prevent the Structural Synchronizer from running when creating ISM repositories.

SHARED LAYOUT TYPES: The capability of creating ISM repositories from models that use shared floor types (i.e., the same layout type at multiple stories) was implemented in v17.02, and works correctly without requiring that the layout type be copied into distinct layout types for each story. However, an old message still appeared indicating that the shared layout type had been duplicated into distinct layout types.

Effect: Erroneous message only. The layout type was not duplicated into separate layout types.

RAM Structural System CONNECT Edition Version 17.01.01 SES Release Notes

Release Date: July 1, 2020

This document contains important information regarding changes to the RAM Structural System. It is important that all users are aware of these changes. Please distribute these Release Notes and make them available to all users of the RAM Structural System. 

This is a minor release, correcting some issues that affected some users of v17.01. The Release Notes for that version contain important information not included here in these abbreviate Release Notes. They can be found at:

https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/48807/ram-ss-v17-01-release-notes

Installation Instructions:

If you have enabled the CONNECTION Client you will automatically be notified of the newest version and will be able to update through that service by simply selecting the update command.

Otherwise, this version can be found on the Bentley Software Fulfilment web page by logging into CONNECT Center and selecting the Software Downloads icon. Search for “RAM Structural System” and select the latest version.

Security Risk Advisory:

Not applicable to this release. Every effort is made to ensure that there are no security risks in the software. There are no known security issues, no issues were addressed in this version.

Error Corrections:

Some program errors have been corrected for this version. Corrections made to graphics, reports, Modeler functions, program crashes, etc., that were considered minor are not listed here. The noteworthy error corrections are listed here in order to notify you that they have been corrected or to assist you in determining the impact of those errors on previous designs. These errors were generally obscure and uncommon, affecting only a very small percentage of models, or had no impact on the results. The errors, when they occurred, were generally quite obvious. However, if there is any question, it may be advisable to reanalyze previous models to determine the impact, if any. In each case the error only occurred for the precise conditions indicated. Those errors that may have resulted in un-conservative designs are shown with an asterisk. We know these errors are disruptive, we apologize for any inconvenience this may cause.

Data Extractor

DATA EXTRACTOR - BEAM REACTIONS*: The reaction values listed in the GravLoadReactionsOnBeams section of the Data Extractor output (from the Post-Processing – Extract Data command in the Manager) were only correct for the first beam on that layout. The reactions for the first beam were erroneously listed repeatedly for all other beams on that floor type.

Effect: Incorrect beam reaction data was given in the Data Extractor output.

Concrete Column

CONCRETE COLUMN CRASH: When Version 17.01 was installed on a machine that had a previous version installed, a key component failed to install, resulting in the program crashing whenever View/Update or any design command was invoked.

Effect: Concrete columns could not be designed. Note that if the previous version was uninstalled through Control Panel prior to installation of v17.01, the problem did not occur. Also, if the program was installed on a machine that did not have a previous version, the problem did not occur.

Frame – Analysis

TORSIONAL IRREGULARITY IN DRIFT REPORT*: The program failed to consider all relevant load cases when determining the governing torsional irregularity values for each story.

Effect: Wrong load case, and its values, might have been identified in the report as the governing load case for the torsional irregularity condition.

TORSIONAL IRREGULARITY IN DRIFT REPORT: In calculation of torsional irregularities, the program included control points even if they were not located inside any diaphragm (or located inside of an opening) at a given level. In this case, the program correctly reported 0.0 for story drift at the control point, but still included that point during calculation of torsional irregularity.

Effect: A control point that is outside a diaphragm or inside an opening, with a reported drift of 0.0, may have been considered, resulting in erroneous values of controlling torsional irregularity ratios.

PROPERTY LABELS: If View/Update is invoked alternating between steel frames and concrete walls, the property labels would not correctly update to match the material. For example, the label for concrete f’c may have been listed as fy, or steel Fy may have been listed as f’c.

Effect: Confusion of property labels (the values were correct for the intended labels)

Frame – Steel Standard Provisions

UNBRACED LENGTH OF COLUMNS WITH SIDEPLATE CONNECTION*: The unbraced length of a column in a multi-story column line having a SidePlate connection was incorrect if the column was unbraced in a given axis at the level.

Effect: When columns having SidePlate connections were unbraced at a level, such as occurs when a level has a partial mezzanine, the unbraced length about the axis without bracing was incorrect and unconservative. The program checked that column using the column's story height, rather than length between braced levels, adjusted by rigid end zones. When the column was braced at each level in both axes, the program used the correct unbraced length. Columns with other beam connection types were unaffected.

In this page you can find information on how to use certain features of RAM Elements with how-tos, tutorials and/or technical notes.

• Wind Load Generation on Members (open structures) - v16.2
• Wind Load Generation on Members (open structures)
• Wind Load Generation on Load Areas
• Mass Source Options
• Rebar Export from Modules and ISM Sync

What Load Combinations are passed from RAM Structural System to Ram Connection?

When Ram Connection for RAM SS is launched the program pulls the load combinations from Ram Frame Steel - Standard Provisions. Combinations from the Ram Frame - Steel - Seismic Provisions mode are also imported when that mode is current (green light for model status).

The user can override this with the Load Combinations ribbon menu dialog box launcher as indicated below.

If this option is unchecked, then Load Combinations need to be added within Ram Connection using Add/edit or Generate in the same ribbon menu.

Why do I get an error, "None load combinations could be read from the model."

Since the program is trying to pull the combinations from RAM Frame, this error will occur for all gravity models that do not have any Ram Frame combinations defined. To proceed in such a model, uncheck the option to "Include RAM Frame - Steel Provisions Mode load combinations as noted above, then manually define or generate new load combinations. 

See Also

RAM Connection Capabilities and Modeling FAQ

RAM Elements Load Combos [FAQ]

[[Ram Connection Seismic Provisions Settings]]

[[Connections for Gravity Members are Designed for Zero Force]]

Troubleshooting Errors when Assigning Connections

Problem Description

In RAM Connection for RAM Structural System, the forces imported from RAM Structural System are zero (0) for all load combinations. The problem occurs at connections with gravity members only. Connections for frame members are designed with the correct non-zero forces.

Reason

RAM Connection identifies notional load cases as lateral load cases and any load combination that includes a notional load case is flagged as a lateral combination. RAM Connection skips combinations identified as lateral combinations in the design of gravity-only members. If all load combinations include notional load cases and there are no load combinations with gravity load cases only, RAM Connection will not have forces results to design connections that include gravity members only.

Steps to Resolve

The best option is to define custom load combinations in RAM Frame - Steel mode - Standard Provisions that include just the gravity loads and exclude notional and lateral loads and import them into RAM Connection with the other load combinations from RAM Frame.

Another option is to generate or manually add these additional load combinations in RAM Connection after importing using the steps below. These combinations will be cleared if combinations are imported from RAM Frame at a later date, however.

Step 1

Click on the Generate button in the Home menu - Load Conditions tool bar.

Step 2

In the Generate Load Combinations dialog, select a factored load combination that matches the design code that is selected and then click on the Generate button. The factored load combinations used in the United States are marked in the screen capture below.

Step 3

Check the boxes for all load combinations that include gravity load cases only. Combinations that include gravity and lateral load cases do not need to be selected. These combinations have been imported from RAM Frame and include the notional load cases. Click the OK boxes to close the dialogs and generate the load combinations.

Can I assign a section such as a HSS or channel to a beam?

Currently, only I-shaped (wide flange) sections can be assigned to beams in RAM Connection. It is not possible to assign other section types, like HSS or channels, to beam members, though they can be used as columns or braces in many connection templates.

What is the difference between Basic Connections and Smart Connections?

The RAM Connection Manual defines these connections as follows:

Basic Connection:  A connection template that can automatically adjust the geometry (position or dimensions) of the connection pieces to fit the connection members. It does not calculate the quantity or dimensions of the connecting pieces (bolts, plates, etc) to resist the applied forces.

Smart Connection: A connection template that can automatically calculate the quantity and dimensions of the connecting pieces (bolts, welds, plate sizes etc) to resist the applied forces.

When basic connections are designed, the program searches through a list of predefined connection templates and selects the first connection in the list that satisfies the design requirements.

When smart connections are designed, the program optimizes the connection parameters. See the RAM Connection Manual for a list of parameters that are optimized for each connection type. If a parameter is not optimized, the program uses a default value that be modified in the Connection Pad as needed.

Some complex connection templates like gusset pate or base plates only have a smart variety. 

Where are the abbreviations used for joint types and connections defined?

The abbreviations are defined in the RAM Connection Manual (available from the help ? or as a pdf from the Windows Start menu). The naming conventions for both joints and connections are listed in Chapter 2, The Connection Database - Database organization. Here is a list of the joint types from that section:

1. Beam – Column Flange (BCF)
2. Beam – Column Web (BCW)
3. Beam – Girder (BG)
4. Beam Splice (BS)
5. Column Splice (CS)
6. Continuous beam over column, column Cap (CC)
7. Column, beams and braces (CBB)
8. Chevron braces (CVR)
9. Vertical X braces (VXB)
10. Column – Base (CB)
11. Column – Base – Braces (CB)

What kinds of forces are considered in various connection types?

In the Joint help is a table of the forces considered in each of the differnt connection types. 

We also offer on demand training for the basic connection configurations. See our RAM Connection Learning path.

How can I change the design code (AISC 360 or BS 5950) or the design method (ASD or LRFD)?

In general, once a connection has been assigned it is associated with a specific design code. In some cases you can change the design code for a connection after the face, but when changing county codes, the connections will have to be replaced after changing the code. 

RAM Connection Standalone version 10.0 or earlier:

1. Click on the Design menu tab at the top of the program window.
2. Find the Assignment toolbar.
3. Double click on the small square box with arrow pointing to the lower right corner to open the Customize Connection Design dialog. Beginning in v10.0, the Customize Connection Design dialog is opened by clicking on the button in the Assignment toolbar that matches the design code selected.
4. Edit the design code (or design method in version 8).

Note, in Ram Connection Stand-alone version 9.0, changing the design code does NOT retroactively alter the assigned code for the existing joints in the file. This was done intentionally so that the user can have some joints designed to one code and other joints designed to another code within a single file. Consequently, if the design code for existing joints needs to be changed, the code should first be changed, then reassign connections to the joints.

Ram Connection Stand Alone version 11.0 and higher:

1. The current design code used for any future assigned connections to joints within the current model or any model is set under the Design Tab. 
2. Use the drop down list at the right of the main graphic to change the code for an existing connection. Note, changing from ASD to LRFD or 2005 to 2010 is generally supported, but changing countries will invalidate most connections since different design templates are used.   

RAM Connection 10.0 or earlier for RAM Structural System:

1. Click on the Design menu tab at the top of the program window.
2. Find the Assignment toolbar.
3. Double click on the small square box with arrow pointing to the lower right corner to open the Customize Connection Design dialog.
4. Edit the design code (or design method).

RAM Connection 11.0 for RAM Structural System:

1. The current code for assigning connections is selected in the Design menu similar to Ram Connection 11 Stand Alone.

RAM Connection 10.0 or earlier for Ram Elements:

The design code and design method is controlled by the code selected for design when performing a design in the RAM Elements model. To change the design code or design method, redesign the model and choose the desired design code.

Changing the design code will not automatically update generated load combinations. After changing the design method, delete and regenerate the load combinations.

 RAM Connection 11.0 or higher for Ram Elements:

1. The current code for assigning connections is selected in the Modules menu.

Furthermore, once a connection is assigned each one includes a an editable field in the spreadsheet for the code: 

Why is the controlling load condition reported as a single load case?

RAM Connection completes a design check for all load conditions, including individual load cases and load combinations. For some connection types, such as a base plate connection with wind uplift, the design for an individual load case may control the design. The single load cases can be removed from consideration as follows:

Open the "Customize Connection Design" dialog using the instructions under "How can I change the design code (AISC 360 or BS 5950) or the design method (ASD or LRFD)?" above. In the dialog, click on the button marked in red below to select the load combinations only.

RAM Connection Standalone (Versions Prior to v9.0)

1. Enter the Connection Pad by either double-clicking the large 3D display of the connection or clicking on the Design menu tab – Connections toolbar – Edit.
2. In the Connection Pad, click on <Loads> to open the Loads worksheet.
3. Click on the Load # associated with the load case and then click on the Delete button on the keyboard to delete it from the worksheet.

Please note that this will not permanently delete the load case results from the worksheet. See frequently asked question above for details.

Information that is modified in the Connection Pad is not saved after clicking the Save button and exiting the dialog.

Any item in the Connection Pad that is marked with a blue arrow (version 9.0 and later) or a red arrow (versions before 9.0) is defined in a dialog outside the Connection Pad. These parameters can be edited in the Connection Pad, but the information will be lost after closing the dialog. To change the parameters permanently, modify the values in the dialog where the information is initially defined. Edit the Joint to modify loads, sections, materials, etc. Edit the seismic provision options in the Customize Connection design dialog.

See Also

Troubleshooting Errors when Assigning Connections

Structural Product TechNotes And FAQs

Mesh Input layer

Why is it necessary to have priorities?

Without the priority system the modeling of floors would require one of two methods:

1. Objects for slabs of different thicknesses, beams, openings etc. could not overlap - this would be very tiresome for all but very simple floors, or
2. Depths would have to be additive. For example, you would have to deduct slab depth from beam depth. If you had to change the slab depth then a change would be required for the beam, unless its depth changed by the same amount.

How can I copy columns or walls below to the same above?

1. Select all of the columns or walls you wish to copy.
2. Choose Edit > Copy (or right-click and choose Copy from the popup menu that appears). Then double click off the edge to select nothing.
3. Choose Edit > Paste (or right-click and choose Paste from the popup menu that appears). The pasted objects are the current selection.
4. Choose Edit > Selection Properties, or right-click and choose Selection Properties.
5. Change Support Set from Below to Above, and click OK.

Note: It is important that you do not abandon the process after pasting. Otherwise, you will have two supports below at various locations, which causes calculation errors.

How can I model curved edges or walls?

Use a series of short straight lines to model any curve in the plan. Do not make the line segments too short or the mesh will become very fine in that region. This approximation should have negligible effect. This also applies to circular drop caps which have to be simulated using a multi-sided polygon.

Can Adjacent Slab Areas be Modeled with a Vertical Gap Between Them?

Slabs that are continuous in plan will have continuity in structural behavior in the model, regardless of the elevations/thicknesses of the slab(s). This continuity occurs even if the slabs are at different elevations and are actually disconnected. The image below summarizes the behavior assumed in RAM Concept.

It is possible to model discontinuous slabs in the same model, but it requires a physical “gap” in plan to create this discontinuity. We recommend modeling any such gap at least 3" wide, as smaller separations can be eliminated during meshing. Another option is to use two separate RAM Concept models to analyze each floor.

Element layer

How can I view the slab without the mesh?

Choose Layers > Element > Slab Summary Plan or go to the visible objects dialog box and check the "Outline only" option under slab elements.

What is the difference between beam and slab elements?

There is no difference unless you modify their behavior. Refer to the RAM Concept Manual Chapter 18 "Defining the Structure" for more information. The main difference between beam and slabs is how they are modeled: a beam is modeled by clicking on two end points along its centerline and always has two parallel edges offset from centerline, while a slab area is closed polygon and can be any shape in plan.

How many nodes or elements are allowed?

There is no limit, other than the limitations of your computer. If you find the program performance too slow, consider any of the following to help:

1. increase the mesh size to reduce the number of elements 
2. delete an imported drawing file that is no longer needed 
3. reduce the number of load cases and/or load combinations
4. reduce the number of design strips or increase the spacing of the design strip cross sections.

How many elements should I use per span or panel?

This cannot be answered directly as it depends upon the structure and loads. The maximum is 32.8 feet (10 meters). To speed the analysis, it is useful to choose a coarse mesh for preliminary design and a fine mesh for final design.

• A coarse mesh might have an element size of span length /6.
• A fine mesh might have an element size of span length /12.

If in doubt, you should investigate the effects of different mesh element sizes.

Columns

Do columns restrain the slab?

Depending upon the defined fixity, columns can provide rotational and lateral restraint. If the far end of a column is defined as a “roller” support (or both ends of the column are pinned) then the column does not provide any lateral restraint to the slab. Columns above the slab do not support the slab vertically, they can only restrain the slab rotationally and laterally.

Why is there deflection at the face of a supporting column or wall?

Columns in Ram Concept connect to the slab finite element mesh at a single node located at the column centroid. They are not solid objects nor do they provide vertical support to multiple nodes. This is apparent viewing the Elements - Standard Plan.

As such, deflections in the slab start from that node and increase towards the face of the column. For small columns this may not matter much, but for large area columns this is significant. 

To mimic the behavior of a stiff column support, we suggest modeling a thick and stiff slab object that overlays the column volume like a mini-drop cap. Be sure to assign a higher priority to this patch of concrete. It is recommended to model this patch with an elevated top of concrete elevation such that the slab centroid aligns with the mid-depth of the patch in order to avoid eccentricity at this joint. 

The same approach could be taken for thick walls supporting the slab as well. A beam or slab object can be used there.

Note, in version 8.02 a feature was added to automate this process. Refer to [[Rigid Support Zones in RAM Concept]]. 

Beams

Where should you define the end points of a beam, at the face of the column, passing the column or at the center line? 

The general preference is to model the beams through the column, extended to the slab edge since it best matches the built condition and how things are formed. Stopping the beam at the column centerline results in a slightly more flexible system.

Walls

Do walls restrain the slab laterally?

Yes, if you select Shear Wall as a property. If the Shear Wall is unchecked then the slab is allowed to slip freely over the top of the wall. The walls rotational stiffness is independent of the Shear Wall setting; use the fixity settings to control the walls rotational stiffness about its longitudinal axis.

What is the effect of specifying walls above?

Wall elements can be used to model the stiffness and spanning ability of walls connected to the slab. Walls above behave similarly to beams in that they stiffen the floor. One could actually model the walls above the slab as beams instead, but it is not generally recommended.

Using beam or slab elements does have some advantages over using wall elements (“wall-beams”):

• Concept design strip cross sections automatically integrate the forces across slab-beam elements; wall-beam elements are ignored in these integrations, however.
• Also, Concept provides you many controls over how slab element results can be displayed; wall-beam elements (like wall elements) can only plot their reactions to the slab.
• However, Concept’s standard slab elements have a torsional stiffness that is proportional to their depth cubed. This can cause a large over-estimation of the torsional stiffness for a very thick slab element if it is adjacent to relatively thin elements. “Wall-beam” elements do not have this problem. As such, walls above that are modeled as upturned beams should use the “No-torsion” beam property.

When modeling wall-beams above the slab, Concept interprets some of the wall element parameters differently than for walls below.

• If the wall-beam is not rotationally fixed to the slab then the wall-beam will have zero torsional stiffness.
• If the wall-beam is not a shear wall then it will have zero axial stiffness. The vertically compressible and rotationally fixed at far end parameters are ignored.

Wall-beam elements have one advantage over slab elements.

• Slab elements of drastically differing thicknesses in the same structure can cause the automatic plotting controls to show (correctly) huge force variations in and adjacent to thick slab elements and almost no variation within the thin slab element areas. This does not generally happen if walls above are modeled as wall-beams.

Do walls above the slab provide rotational restraint?

There is no restraint at the far end of a wall above. (Even if “Rotationally Fixed at Far End” is checked, it is ignored).

See Also

[[Rigid Support Zones in RAM Concept]]

The technotes and FAQs in this section cover various topics that pertain to STAAD(X) Tower.

• License Management Tool fails to open

• Section databases implemented in STAAD(X) Tower