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Steel connection design and detailing software.

Overview

Limcon is productivity-geared steel connection design software. Connections types include beam to column, brace end, member splices, anchorage to concrete, and complicated multi-member joints. By using a library of standard connection types, designers can arrive at results in a remarkably short time.

Specialty software for steel tower analysis and design to a number of international standards.

Overview

MStower is special purpose software for the analysis and design of steel transmission and communication towers to a range of international standards. A comprehensive library of panel types and ancillary equipment allow quick creation of the structure.

If a “SPRING TENSION” command is specified and the spring is stretched along the positive global direction (due to a positive global deflection of the node to which the spring is attached), then the spring is identified to be in tension and you will have the spring support reaction as negative by the virtue of it being opposite to the displacement. If however, the displacement is negative, the spring is identified to be in compression and the spring will be switched off from the model.

If a “SPRING COMPRESSION” is specified and the spring is compressed along the negative direction of the global axis (due to negative global deflection of the node to which the spring is attached), the spring is identified to be in compression and you will have the spring support reaction as positive by the virtue of it being opposite to the nodal displacement in the negative direction. If the displacement is positive, the spring will be identified to be in tension and will be switched off.

In the following figure, consider a compression only spring support is specified in Global X direction. Due to the applied load in negative X direction, the support node (node 9) will displace in the negative global X direction. So the spring support will be under compression and the support reaction in Global X direction is positive.

In November of 2013, the exciting news that the business of Engineering Systems, and the Microstran software product line, are now part of Bentley Systems was announced. The popular software products Microstran, Limcon, and MStower are now part of Bentley’s structural analysis and design portfolio alongside RAM and STAAD. Further, the Engineering Systems staff has joined our Bentley offices in Australia, bringing with them over 25 years of experience in developing and supporting a market leading software solution for structural engineers and designers. This article addresses some commonly asked questions concerning the acquisition.

How does the acquisition affect the Microstran product line?

Microstran is now being packaged and licenced a little differently than it has been in the past. Specifically, Microstran is now offered in three tiers:

• Microstran
• Microstran.Pro
• Microstran.Advanced

Each of these tiers contains an increasing number of features that in the past were sold as separate add-ons by Engineering Systems. Microstran contains elastic critical load analysis and master-slave constraints. Microstran.Pro contains the prior two add-ons, plus dynamic analysis (eigenvalues), cable elements, reinforced concrete design, and steel detailing neutral format. Microstran.Advanced contains all previously mentioned add-ons plus moving loads, gap and fuse elements, and response spectrum analysis.

The design code standards are still offered as individual add-ons that can be applied to any of the three tiers. This is also true of the integrated steel connection design feature within Microstran.

How does the acquisition affect maintenance and support?

Engineering Systems customers will be contacted just prior to the expiration of their existing maintenance plan with Engineering Systems. At this time you will be presented options for moving onto a Bentley SELECT maintenance plan, which will give you access to a wealth of new benefits in support of your Microstran products. A Bentley SELECT plan includes:

• Annual software upgrades and incremental updates – accessible any time
• Unlimited technical support - 24 hours/day, 365 days/year
• Software licencing over the internet (no more dongles)
• Floating network licencing
• Online training resources
• Access to technology previews and early adopter programs
• Free iPad and desktop utility applications
• Ability to review and manage your software usage
  

See the following link for more information on Bentley SELECT:

http://www.bentley.com/en-US/Subscriptions/Bentley+SELECT/

What does the future hold for the Microstran product line?

Engineering Systems technology is an important part of our initiatives to better serve Australia, New Zealand, and greater SEAPAC. In the coming months, you can expect the following enhancements:

• Access to your products without the need of a hardware dongle.
• Export capabilities that will allow reuse of Microstran models in other Bentley design, detailing, collaboration, and mobile products.
• These benefits will be available only to Bentley SELECT subscribers.
  

Further, later in 2014 we will be releasing a state of the art tower analysis and design product that is the best of Bentley and Engineering Systems combined technology. Customers whose MStower product is covered under Bentley SELECT will not be required to pay an upgrade fee for this product.

Who do I contact for more information?

You may continue to direct queries to:

sales@microstran.com.au

support@microstran.com.au

Alternatively, if you are new to the Microstran product line and would like more information, please contact:

• Sandra Mora, at Sanrda.Mora@bentley.com in Australia, New Zealand, and Southeast Asia.
• Ingrid Brock, at Ingrid.Brock@bentley.com in all other regions.
  

Existing Bentley customers may also contact their current sales representative.

Problem Description

Some wind and/or seismic load cases have been analyzed in RAM Frame but are not included in any of the generated load combinations.

Reason

This is typically associated with the option selected for Notional Loads in the load combination dialog:

In most cases, the wind and seismic lateral loads have been defined with the box for "Generate Additional Load Cases for Analysis with Tension-Only Members" checked. This creates positive and negative lateral load cases in the x and y directions. However, the notional load case has been defined without the same option checked.  This creates only positive notional load cases; negative notional load cases are not generated.

If "Consider with all combination in direction of lateral load" is selected for Notional Loads in the load combination dialog, the program recognizes that there are negative wind and/or seismic load cases but no negative notional load cases. Currently, the RAM Structural System load combination generator will generate a combination if all of the load cases in the combination are available, but will not generate the combination if any of the load cases in the combination are not available. Because there are negative wind and/or seismic load cases but no negative notional load cases, no combinations containing the negative lateral load cases are generated.

Steps to Resolve

Change the Notional Load Case and check the box for "Generate Additional Load Cases for Analysis with Tension-Only Members."

See Also

Structural Product TechNotes And FAQs

Error or Warning Message

The following message appears in a black DOS window when attempting to run an analysis in RAM Elements or a design in one of the design modules:

OMP: Warning #72: KMP_Affinity: affinity only supported for Intel processors.
OMP: Warning #71: KMP_Affinity: affinity not supported, using "disabled"

Explanation

The direct sparse solvers used by RAM Structural System and RAM Elements utilize multiprocessing libraries provided by Intel. The libraries function properly with Intel processors but not with AMD processors.

How to Avoid

The error has no effect on the analysis. The error window can be safely minimized and ignored. If the error window is closed, however, the program will crash.

In the main program, you can also change to the in-core direct solver to avoid the error.

The solver type cannot be changed in the modules. You will need to minimize and ignore the error window to prevent a crash from occurring.

See Also

[[RAM Frame Troubleshooting [TN] ]]

1. While I can look at the model with Stress Ratio values annotated next to the steel members that I have asked to be checked, when I do the member query (double clicking on the members) I don't see the Design Property and Steel Design boxes anymore. Why is that?
2. STAAD is checking deflection for beams or girders for all the load combinations in my model. Is there a way to tell STAAD which load combination to check?
3. The steel design output indicates a slenderness failure (KL/r exceeds allowable). Why? The axial force on the member is very small.
4. I set my deflection limit to L/360, but the maximum deflection indicated in the summary of node displacements in PostProcessing shows a deflection of 1.5 inches. Isn't this above the limit that I set?
5. THE VALUE OF E FOR MEMBER NNN DOES NOT SEEM RIGHT. What does this mean?
6. The KL/r value that STAAD reports for the Y axis for a single angle does not match what I get from my hand calculation. Can you explain why?
7. I have a large model with several hundred members which have been assigned steel sections. I am doing a code check and I want to find out which of those members have failed. Can I get a list of just those members without having to scroll through hundreds of pages of steel design output?
8. I am running STAAD.Pro 2003. In the TRACK 2 output for the American LRFD code, I find some terms that I am not familiar with. Can you tell me what those are?
9. I am running STAAD.Pro 2002. In the TRACK 2 output for the AISC ASD code, I find some terms that I am not familiar with. Can you tell me what those are?
10. I am using STAAD.Pro 2003 and I want to use physical members to do a steel design. I know how to manually create physical members by selecting the individual members, right-clicking the mouse and choosing Form Member. But if I have hundreds of these members, can I do it faster?
11. I want STAAD.Pro to perform a steel design based on the LRFD 3rd Ed rather than the 2nd Edition. The output always says "LRFD 1994". How do I tell it what code to use?
12. I am not sure how STAAD deals with the specifications of the unsupported length for top flange compression.
13. I would like to perform code checking on a 8" x 2 1/2" x 10 Gage channel per the AISI Coldformed steel code. But this channel is not listed in the sections available in your database. Can I assign it using a user provided table?
14. Increasing the NSF value in Steel Design does not change the Failure Ratio for a member, Why?
15. I ran my STAAD model and got an error message which stated that "This version does not design prismatic sections". What does this mean?
16. The KL/ry reported for a double angle does not match my hand calculations. I am designing the section per the AISC ASD 9th edition code.
17. I am using the composite beam design capabilities. But the output does not show any evidence of this design. Why?
18. How does one change the value of the yield strength of steel?
19. In STAAD/Pro 2000 and STAAD.Pro, I no longer see the UNL parameter for the AISC ASD and LRFD codes. Instead, I see the parameters UNT and UNB. Why?
20. The steel design output for a tube section checked per the AISC ASD code indicates an SY and SZ substantially different from the values which are reported in the AISC publication. Why?
21. How can I check whether the story drift of the floors are within allowable limits?
22. Utilizing DFF in STAAD only helps one check the local deflection. What if I want to check the drift of a column / beam frame?
23. Can I get STAAD to check deflection in both axes?
24. Will STAAD explicitly state that the beam has passed the deflection criteria?
25. What are the design parameters which control deflection check?
26. THIS VERSION DOES NOT DESIGN TAPERED POLE SECTIONS (MEMBER 1). What does this error message mean?
27. I am using STAAD to do steel design per the AISC code. For 2 members with similar cross sections, one passes, the other fails. Fact is, the one which fails has almost no load on it. The other is significantly more stressed but still passes. Is something wrong in the steel design calculations that STAAD is doing?
28. What do the following parameters mean? NSF 0.85 ALL, BEAM 1.0 ALL, KY 1.2 ALL, RATIO 0.9 ALL, LY 18 ALL, LZ 18 ALL, CHECK CODE ALL
29. When one does the AISC code check or member selection, what are the calculations the program is performing?
30. When I run code checking [as per BS5950] of the steel prismatic members which were defined in the User Provided Table, I get the following message in my output file:
    DESIGN NOT PERFORMED WITH PRISMATIC PROPERTIES
    USER-TABLE MAY BE USED TO DESIGN PRISMATIC SECTIONS
31. I am using STAAD to perform steel design on a member per the AISC ASD code. I want the column to be designed based on an unbraced length of 20 ft. I have set the UNT and UNB values to 20 ft, but STAAD appears to consider only a 10 feet length in its KL/r calculations. How do I correct this problem?
32. How do I get a design parameter, say the RATIO parameter, to be applied only to certain load cases?
33. I run the analysis of a 3-D bridge truss model and requested a CODE CHECK of the members. The results of this code check do not correspond to my hand calculation results.
34. What is the LX parameter used for?
35. The KL/r value that STAAD reports for a single angle member does not match my hand calculation. Design is per the AISC ASD 9th edition code.
36. What are the SSY and SSZ parameters for AISC ASD based steel design?
37. The KL/ry reported for a T shape does not match my hand calculations. I am designing the section per the AISC ASD 9th edition code.
38. Can you provide me with some help on how I can include deflection check as one of the criteria in steel design?
39. In the output for steel design, what does the term "dff" represent?
40. In STAAD-III, I was able to get a steel design for members defined using the PRISMATIC property attribute per the AISC ASD code. I cannot do this in STAAD/Pro. Why?
41. In the context of design, what is meant by the term Ratio?
42. I have multiple sets of design in the same STAAD file and I am only able to see the results for the final set in the Postprocessing mode (GUI). How can I view the results for all design sets in the GUI ?
43. How is the shear stress calculated in STAAD.Pro for AISC design code ?
44. Do you have a plan that STAAD.Pro implements AISI 2007 edition?
45. A structure that I'm working on I have a 11.6m beam which supports transverse beams and bracing. How can I determine the overall deflection of the 11.6 m beam and check if it is complying with the L/500 criteria?
46. I am changing the K and FYLD parameters for some members but the values reported in the design output indicate that those did not change. Why ?
47. Can the CHECK CODE command be applied for a created group of members?
48. I have done a buckling analysis and can see the buckling factors. However when I attempt to do a steel design, all members fail. Why ?

1. While I can look at the model with Stress Ratio values annotated next to the steel members that I have asked to be checked, when I do the member query (double clicking on the members) I don't see the Design Property and Steel Design boxes anymore. Why is that?

 Design Property and Steel Design tabs are not displayed for members which have not been designed. Are you sure you are clicking a member for which the design has been done? Sometimes, when ratios are annotated on the screen, the picture may become quite cluttered with data and in an effort to double click on a designed member, one may end up clicking on a member for which design has not been performed. So, first check that the member you are double-clicking has indeed been designed. If you are certain that STAAD has done the design and evidence of that exists in the analysis output file and in the postprocessing Unity Check tables, but still you are not able to see these tabs in the dialog box which comes up when you double click on the member, please send us your .std model and our support representatives will look into that.

2. STAAD is checking deflection for beams or girders for all the load combinations in my model. Is there a way to tell STAAD which load combination to check?

You have to use the LOAD LIST command to achieve this. Supposing you want to check deflection for combination cases 81 and 82. And assume that L/Deflection has a limit of 240. The command sequence required to achieve this is

LOAD LIST 81 82
PARAMETER
CODE AISC
DFF 240 ALL
CHECK CODE ALL

However, after these commands, you have to reset DFF to a very small number so that deflection does not become a criteria for any further design operations. That is because, once a parameter is specified in STAAD, it stays that way till it is changed again. So, after the above, you need to specify

PARAMETER
CODE AISC
DFF 1 ALL

3. The steel design output indicates a slenderness failure (KL/r exceeds allowable). Why? The axial force on the member is very small.

The code has requirements which say that the KL/r ratios for a member should not exceed certain allowable limits. For members subjected to tensile forces, the code suggests one limit, and for members subjected to compressive forces, there is another limit.

This check does not consider the amount of the axial force. It only looks at the sign of the force to determine if it is a tensile force or compressive force.

In most codes, this is the first check STAAD does on a member. If the member fails the check, no further calculations are done for that member.

So, STAAD performs these checks by default. However, the code does not offer any guidelines on what must be the minimum magnitude of the axial force for the member to become a candidate for this check.

So, in STAAD, two parameters are available - one called MAIN and another called TMAIN if you wish to bypass this check (TMAIN is available for some codes only). MAIN=1 is for bypassing the slenderness check in compression, and TMAIN=1 is for bypassing the slenderness check in tension.

4. I set my deflection limit to L/360, but the maximum deflection indicated in the summary of node displacements in PostProcessing shows a deflection of 1.5 inches. Isn't this above the limit that I set?

During steel design per the AISC ASD code, there are two types of deflection checks you can perform with STAAD. They are

1. Check for local deflection. This is usually applicable to members which are connected at both their ends to other members.
2. Check for the relative displacements between the nodes such as for a cantilever beam.

LOCAL DEFLECTION is defined as the maximum deflection between the 2 ends of the beam relative to a straight line connecting the 2 ends of that member in its deflected position.

If you go to

Help - Contents - Technical Reference - Commands and Input Instructions - Printing Section Displacements for Members

you will find a diagram indicating this is in figure 5.41.

To obtain more information on the difference between the 2 methods of deflection checking, please go to

Help - Contents - Technical Reference - American Steel Design - Design Parameters (which comes after Allowables per AISC code)

It will bring up section "2.4 Design Parameters"

At the end of the parameters table, you will see several notes. Please read Notes items 1 through 4 for the description of the two methods.

As you can see there, the default condition, which is also represented by a value of zero for the CAN parameter, is to perform the LOCAL DEFLECTION check.

Your question indicates that what you are looking for is a check of the nodal deflections. The cantilever style check STAAD offers is probably the solution for your problem. If so, specify the CAN parameter with a value of 1.

5. THE VALUE OF E FOR MEMBER NNN DOES NOT SEEM RIGHT. What does this mean?

The steel design output for several members is accompanied by the following warning message :

WARNING : THE VALUE OF E FOR MEMBER 21 DOES NOT SEEM RIGHT.

WARNING : THE VALUE OF E FOR MEMBER 22 DOES NOT SEEM RIGHT.

WARNING : THE VALUE OF E FOR MEMBER 23 DOES NOT SEEM RIGHT.

During steel design, there is a check for ensuring that the Modulus of Elasticity (E) specified for the member is within the range that is normal for steel. This is because, E is a crucial term that appears in many equations for calculating section capacities and the program wants you to know if the value appears to be abnormal.

In STAAD, you specify E either explicitly under the CONSTANTS command block or through the DEFINE MATERIAL block, as in the examples below.

Example 1 :

UNIT KIP INCH
CONSTANTS
E 29000 ALL
DENSITY 0.283E-3 ALL

Example 2 :

UNIT METER KNS
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.05e+008
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-005
DAMP 0.03
END DEFINE MATERIAL
CONSTANTS
MATERIAL STEEL MEMBER 101 TO 121

So, if you are specifying an E value which is significantly different from that for steel, such as say, Aluminum, and then later asking the member to be designed according to a steel code, as in the following example, the above-mentioned warning message will appear.

UNIT FEET POUND
DEFINE MATERIAL START
ISOTROPIC ALUMINUM
E 1.44e+009
POISSON 0.33
DENSITY 169.344
ALPHA 1.28e-005
DAMP 0.03
END DEFINE MATERIAL

CONSTANTS
MATERIAL ALUMINUM MEMBER 21 TO 30

..
..
PARAMETER
CODE AISC
CHECK CODE MEMBER 21 TO 30

6. The KL/r value that STAAD reports for the Y axis for a single angle does not match what I get from my hand calculation. Can you explain why? 

For single angles, the local Y and Z axes are the principal axes as shown below:

The KL/r value is computed using ry and rz which are based on the principal axis system. Chances are that your handculation uses the geometric axes.

7. I have a large model with several hundred members which have been assigned steel sections. I am doing a code check and I want to find out which of those members have failed. Can I get a list of just those members without having to scroll through hundreds of pages of steel design output?

There are 2 methods for finding just those members which have failed the steel design checks.

1. From the Select menu, choose By Specification - All Failed beams. The members which fail the check will be highlighted. You can then isolate them into a New View to examine them in greater detail. Double click on those members or use Tools - Query - Member to access a dialog box with tabs called Steel Design and Design Property to see the cause of the failure along with allowable and actual stresses and critical conditions.
2. In the Post processing mode, go to the Beam page along the left side of the screen. One of the sub-pages will be Unity Check. A table will appear along the right side of the screen. One of the tabs of that table is Failed Members. Select this tab, and click on each row of the table to look at each such member individually.

8. I am running STAAD.Pro 2003. In the TRACK 2 output for the American LRFD code, I find some terms that I am not familiar with. Can you tell me what those are?

The terms reported in the TRACK 2 output for American LRFD are :

AX = Cross section Area.
AY : Area used in computing shear stresses along local Y axis.
AZ : Area used in computing shear stresses along local Z axis.
PY : Plastic Section modulus about local Y axis.
PZ : Plastic Section modulus about local Z axis.
RY : Radius of gyration about local Y axis.
RZ : Radius of gyration about local Z axis.

PNC : Axial compression capacity.

pnc : Axial compressive force used in critical condition.

PNT : Axial tensile capacity.

pnt : Axial tensile force used in critical condition.

MNZ : Nominal bending capacity about local Z axis.

mnz : Bending moment about local Z axis, used in critical condition.

MNY : Nominal bending capacity about local Y axis.

mny : Bending moment about local Y axis, used in critical condition.

VN : Shear capacity.

vn : Shear force associated with critical load case and section location.

DFF : Permissible limit for checking length to deflection ratio.

dff : Actual length to deflection ratio.

9. I am running STAAD.Pro 2002. In the TRACK 2 output for the AISC ASD code, I find some terms that I am not familiar with. Can you tell me what those are?

The terms reported in the TRACK 2 output for AISC ASD are :

AX = Cross section Area
AY : Area used in computing shear stresses along local Y axis
AZ : Area used in computing shear stresses along local Z axis
SY : Elastic Section modulus about local Y axis
SZ : Elastic Section modulus about local Z axis
RY : Radius of gyration about local Y axis
RZ : Radius of gyration about local Z axis

FA : Allowable axial stress. If failure condition involves axial tension, this is the allowable axial tensile stress. If failure condition involves axial compression, this is the allowable axial compressive stress.

fa : Actual axial stress.

FCZ : Allowable bending compressive stress about local Z axis.

FTZ : Allowable bending tensile stress about local Z axis.

FCY : Allowable bending compressive stress about local Y axis

FTY : Allowable bending tensile stress about local Y axis.

fbz : Actual bending stress about local Z axis, used in the design condition

fby : Actual bending stress about local Y axis, used in the design condition.

FV : Allowable shear stress.

Fey : Euler stress for buckling about local Y axis.

Fez : Euler stress for buckling about local Z axis.

DFF : Permissible limit for checking length to deflection ratio.

dff : Actual length to deflection ratio.

10. I am using STAAD.Pro 2003 and I want to use physical members to do a steel design. I know how to manually create physical members by selecting the individual members, right-clicking the mouse and choosing Form Member. But if I have hundreds of these members, can I do it faster?

In STAAD.Pro 2003, you can use the Auto-Form member option to let the program automatically create physical members for you. From the Member Design page in the Steel Design Mode, go to Member Design | Physical Members | Auto Form Members. The rules it uses to create physical members are as follows:

1. All elements must form a single continuous line. But they do not have to form a straight line. Thus curved members may be formed.
2. There must be a free end. Whilst curved members are allowed, they cannot form a closed loop.
3. All elements should have the same beta angle.
4. All elements must point in the same direction. Check with the orientation labels if necessary. Use the reverse element command on elements that point the wrong way.
5. None of the elements can be part of another member.
6. The section properties must be consistent at each element end. Elements can taper along their length, but where one element ends and the next starts, they must have the same section reference.
7. All elements must be made from the same material.
8. Vertical segments are converted into columns first.

11. I want STAAD.Pro to perform a steel design based on the LRFD 3rd Ed rather than the 2nd Edition. The output always says "LRFD 1994". How do I tell it what code to use?

If you wish to use LRFD 3rd Edition Code, you can write CODE LRFD3 when providing the design parameters.

The 3rd edition of the American LRFD steel code has been implemented along with the 2nd edition. In general, the principles outlined in the code for design for axial tension, compression, flexure, shear etc., are quite similar to those in earlier versions of the code. The major differences are in the form of incorporation of the Young’s modulus of steel in the various equations for determining various limits like slenderness and capacities.


Consequently, the general procedure used in STAAD for design of steel members per the AISC-LRFD code has not changed significantly. Users may refer to Section 2 of the STAAD.Pro Technical Reference manual for these procedures.


Those who wish to use the 1994 edition of the code can still do so by specifying the code name as:

CODE LRFD2

An example of commands used for performing design based on the new and old codes are as shown.


Example for the LRFD-2001 code (3rd Ed)


UNIT KIP INCH
PARAMETER
CODE LRFD


or

CODE LRFD3
FYLD 50 ALL
UNT 72 MEMBER 1 TO 10
UNB 72 MEMB 1 TO 10
MAIN 1.0 MEMB 17 20
SELECT MEMB 30 TO 40
CHECK CODE MEMB 1 TO 30

Example for the LRFD-1994 code (2nd Ed)

UNIT KIP INCH
PARAMETER
CODE LRFD2
FYLD 50 ALL
UNT 72 MEMBER 1 TO 10
UNB 72 MEMB 1 TO 10
MAIN 1.0 MEMB 17 20
SELECT MEMB 30 TO 40
CHECK CODE MEMB 1 TO 30

12. I am not sure how STAAD deals with the specifications of the unsupported length for top flange compression.

For example, if I have a truss whose top chord is laterally supported at every other node (i.e. two member lengths being unsupported), then should I highlight every two members (of the top chord) seperately and then tell the program to take their combined length as being unsupported, or should I highlight the entire top chord and then specify the correct unsupported length.

The value you specify for UNL is what STAAD uses for the expression Lb which you will find in Chapter F of the AISC ASD & LRFD codes. Starting from Version 2001, UNL has been replaced with UNT and UNB for these codes. If the Lb value for the top flange is different from that for the bottom flange, you have to specify the corresponding values for UNT & UNB.

So if the bracing points are at every alternate node, first determine the distance between the alternate nodes. Then assign that value for both beams which exist between those nodes.

For example, if you have

Member 5 connected between nodes 10 and 11, and is 6.5 ft long
Member 6 connected between nodes 11 and 12, and is 7.3 ft long

and both the top and bottom flanges are braced at nodes 10 & 12, you can assign

UNIT FEET
PARAMETER
CODE AISC
UNT 13.8 MEMB 5 6
UNB 13.8 MEMB 5 6

To assign these parameters using the GUI, while in the Modelling mode, select the Design page from the left side of the screen. Make sure the focus is on the Steel sub-page. On the right side, select the proper code name from the list box on the top. Click on the Define Parameters button along the bottom right side. In the dialog box which comes up, select the tab for UNT and UNB, specify the value, and assign it to the appropriate members.

13. I would like to perform code checking on a 8" x 2 1/2" x 10 Gage channel per the AISI Coldformed steel code. But this channel is not listed in the sections available in your database. Can I assign it using a user provided table?

At present, sections whose data is specified using a "User Provided Table" (see section 5.19 of the Technical reference manual for details) cannot be designed or checked per the AISI code. However, the following approach may be used to get around this limitation.

You may add your section to the STAAD AISI section database, so that your section becomes a permanent part of the database. This can be done using the following method.

From the Tools menu, select Modify Section database. The various steel databases available in the program will be listed in a dialog box. You will find ColdFormed (US) at the end of this list. Expand this list, and choose Channel with Lips or Channel without Lips as the case may be. On the right half of the dialog box, the Add option will become activated. Select that, and you will now be provided with an interface through which you can add your channel to the list. Save and Close it.

You can now go to the Commands menu, and choose Member property - Steel Table - AISI Table to obtain visual confirmation that this new section is permanently included among the list of channel sections. You should now be able to assign this new section to the members through the usual property pages and menus.

14. Increasing the NSF value in Steel Design does not change the Failure Ratio for a member, Why?

In the design input parameters, I set NSF to .85 for my steel design. The design output result showed a failure ratio of 1.063 on Member 1. I then proceeded to change the NSF parameter to 1.0. This time, the design output result showed the same failure ratio of 1.063. It seems that nothing has changed. I increased the net section factor by 0.15, but the stress ratio hasn't changed? 

The NSF value has an effect only on allowable axial tensile capacity, and the actual tensile stress.

If axial tension, or axial tension plus bending, are not what determine the critical condition, changing the value of NSF will not have any impact on the failure ratio. For example, if the critical failure condition for a member is compression, changing NSF will have no impact.

Check to see what the critical condition is. It will show up in the form of expressions such as:

AISC H1-1 or Slenderness, etc.

15. I ran my STAAD model and got an error message which stated that "This version does not design prismatic sections". What does this mean?

In the earlier versions of STAAD (STAAD-III), the code check for prismatic sections was done using allowable stresses which are arbitrarily chosen as 0.6 x Fy. However, this assumption of 0.6Fy was not based on any code specific requirements. The word PRISMATIC is meant to indicate a section of any arbitrary shape. But neither the AISC nor LRFD codes provide guidelines for design of arbitrary shapes. Section capacities are dependent upon aspects such as the width to thickness ratio of flanges and webs, lateral torsional buckling etc. From that standpoint, using an allowable stress of 0.6Fy for PRISMATIC sections was not always conservative.

A way around this limitation (lack of specific guidelines) would have been to use the rules of a known shape, such as a Wide Flange, for designing prismatic shapes. That would require knowledge of equivalent flange and web dimensions. When the properties are defined using the PRISMATIC option, there is no means to convey information such as dimensions of flanges or webs to the STAAD design facility. Hence, the design of PRISMATIC shapes is not supported in STAAD/Pro. You may get around this problem by defining the properties using the GENERAL section in a User Provided Table. For a GENERAL section, STAAD provides the means for providing dimensions of the components that are critical from the standpoint of computing allowable stresses. The allowable stresses for a GENERAL section are computed using the rules of a wide flange shape (I shape). As a result, the allowable stress value will be dependent on attributes such as dimensions of the cross section, length of the member, etc.

16. The KL/ry reported for a double angle does not match my hand calculations. I am designing the section per the AISC ASD 9th edition code.

For singly symmetric shapes such as Tees and Double Angles, the KL/r value for the Y axis is calculated by STAAD using the rules for flexural torsional buckling as explained in page 3-53 of the AISC ASD manual. It is not calculated as Ky multiplied by Ly divided by ry. 

17. I am using the composite beam design capabilities. But the output does not show any evidence of this design. Why?

There are 2 sets of data associated with analysing and designing a composite beam.

Step 1 : Define the member properties as a composite beam. To do this, one has to use the "TA CM" option as explained in Section 5.20.1 of the STAAD.Pro Technical reference Manual. For example, if member 1 is a composite beam made up of a 3.0 inch thick slab on top of a W18X35, and the grade of concrete is 4.0ksi, one would have to specify

UNIT INCH KIP
MEMBER PROPERTIES
1 TA CM W18X35 CT 3.0 FC 4.0

Step 2 : Parameters for steel design. This is what you find in Section 2.9 of the STAAD.Pro Technical reference Manual. These are the attributes which are to be used in the actual design equations, using the expression PARAMETER, as in,

PARAMETER
CODE AISC
BEAM 1 ALL
TRACK 2 ALL
FYLD 50 ALL
CMP 1 ALL
DR1 0.3 ALL
WID 60 ALL
FPC 4 ALL
THK 4 ALL
SHR 0 ALL
DIA 0.75 ALL
HGT 4 ALL
RBH 2 ALL
CHECK CODE ALL

The most important thing to note here is the usage of the parameter CMP. Unless it is set to 1.0, STAAD does not design the beam as a composite section. The beam will be designed as a pure steel beam section in the absence of the "CMP 1" parameter.

18. How does one change the value of the yield strength of steel?

FYLD is one of the items specified as parameters for steel design. The STAAD Technical Reference manual and International Design Codes manual contain information on specifying parameters for steel design.

There are example problems in the STAAD Example manual demonstrating how parameters are specified for design. The example below shows some typical post-analysis commands.

PERFORM ANALYSIS PRINT STATICS CHECK
PRINT MEMBER FORCES LIST 5 7
PRINT ELEMENT STRESSES LIST 10 TO 16
UNIT KIP INCH
PARAMETERS
CODE AISC
UNT 1.0 ALL
UNB 20.0 ALL
LY 60 MEMBER 36 40
LZ 60 MEMBER 36 40
FYLD 46.0 MEMBER 47 50
CHECK CODE ALL
FINISH

If you prefer to use the graphical method, this is how you can specify it. From the left side of the screen, select the Design page. Make sure the sub-page says Steel. On the right hand side of the screen, go to the top, and choose the appropriate code.

Select the members on the structure for which you wish to assign the FYLD parameter.

Then, on the bottom right hand side of the screen, you will find a button called Define Parameters. Click on that button. Select the FYLD tab. Specify the value, and click on Assign.

19. In STAAD/Pro 2000 and STAAD.Pro, I no longer see the UNL parameter for the AISC ASD and LRFD codes. Instead, I see the parameters UNT and UNB. Why?

In versions of STAAD prior to STAAD/Pro 2000, the mechanism for specifying the unsupported length of the compression flange was through the means of the UNL parameter. However, the drawback of this command is that if the value for the top flange is different from that of the bottom flange, there wasn't any means to communicate that information to STAAD.

Consequently, 2 new commands were introduced, namely, UNT and UNB.

UNT stands for the unsupported length of the TOP flange of the member for calculating the capacity in bending compression and bending tension.

UNB stands for the unsupported length of the BOTTOM flange for calculating the capacity in bending compression and bending tension.

To avoid the confusion that may arise from having 3 separate parameters to specify 2 items of input, we no longer mention the UNL parameter. However, to enable the current versions of STAAD to analyze input files created using the older versions of STAAD, the UNL parameter continues to work the way it did.

These 2 new parameters are to be used in place of UNL. If UNT/UNB is specified in addition to UNL, UNL will be ignored. If neither UNT nor UNB are specified, but UNL is specified, the value of UNL will be used for both top and bottom flange.

20. The steel design output for a tube section checked per the AISC ASD code indicates an SY and SZ substantially different from the values which are reported in the AISC publication. Why?

In steel design per the AISC ASD code, the elements of the cross section (flange, web etc.) have to be put through some tests per Chapter B of the code. These tests are required to classify the cross section into one of 3 types - Compact, Non-compact, Slender.

If a section is classified as slender, the allowable stresses on the section have to be determined per the rules of Appendix B of the code. For slender "stiffened elements", which is the type a tube falls into, the effective section properties have to be calculated and those effective properties must then be used in computing the actual stresses.

The extent of the cross section deemed effective depends on the bending moment on that section. It is very likely that for the critical load case, the effective properties are less than the gross section properties, which is why you see the reduced Sz and Sy in the output.

21. How can I check whether the story drift of the floors are within allowable limits?

If you have STAAD.Pro 2001 Build 1005 or Build 1006, you can specify a command called

PRINT STORY DRIFT

in your input file. Run the analysis. Then check your output file, The drift for each story will be reported. You will have to manually verify that this is within your allowable limits.

22. Utilizing DFF in STAAD only helps one check the local deflection. What if I want to check the drift of a column / beam frame?

If my joint displacement printout says that joint of a column/beam joint has moved 1.42 inch in the global X, then my drift ratio is 18x12/1.42 = 152.11, but the "dff" says 1072 for the same column, then where is the dff being measured?

When the DFF parameter is specified, the deflection checks during steel design are performed on the basis of so called "local axis deflection", not the nodal displacements in the global axis. For this reason, it is not possible to include storey drift checks into the steel design calculations at present.

If you want additional information on local axis deflection, please refer to example # 13, and Section 5.42 of the STAAD Technical Reference Manual.

23. Can I get STAAD to check deflection in both axes?

 Yes. However, rather than check the deflection for each axis independently, STAAD finds the resultant deflection "d" and compares the "L/d" (length to deflection ratio) against the allowable limit specified by you through the DFF parameter.

24. Will STAAD explicitly state that the beam has passed the deflection criteria?

When STAAD performs steel design (code checking as well as member selection), it checks several conditions required by the code. The one which gives rise to the highest unity check is the one determined as critical. If the deflection criteria ends up being the worst condition, you will see it being reported as the critical condition.

You can verify whether a member has passed the deflection check by looking at the terms "DFF" and "dff" in the steel design output. "DFF" is the value you input. "dff" is the value the program calculates as the actual "L/d" ratio. If "dff" is larger than "DFF", the member is deemed safe for deflection.

25. What are the design parameters which control deflection check?

1) DFF : This is the value which indicates the allowable limit for L/d ratio. For example, if a user wishes to instruct the program that L/d cannot be smaller than 900, the DFF value should be specified as 900. The default value for DFF is 0. In other words, if this parameter is not specified as an input, a deflection check will not be performed.

2) DJ1 and DJ2 : These 2 quantities affect the "L" as well as the "d" in the calculated L/d ratio. They represent node numbers that form the basis for determining L and d.

By default, DJ1 and DJ2 are the start and end nodes of the member for which the design is being performed, and "L" is the length of the member, namely, the distance between DJ1 and DJ2. However, if that member is a component segment of a larger beam, and the user wishes to instruct STAAD that the end nodes of the larger beam are to be used in the evaluation of L/d, then he/she may input DJ1 and DJ2 as the end nodes of the larger beam. Also, the "d" in L/d is calculated as the maximum local displacement of the member between the points DJ1 and DJ2. The definition of local displacement is available in Section 5.42 of the STAADPro Technical Reference Manual, as well as in Example problem # 13 in the STAADPro Examples Manual.

A pictorial representation of DJ1 and DJ2, as well additional information on these topics is available under the "Notes" section following Table 2.1 in Section 2.8 of the STAADPro Technical Reference Manual.

If you use the design parameter TRACK 2.0, you will see a term called "dff" in the STAAD output file. This terms stands for the actual length to deflection ratio computed by STAAD. If "dff" is smaller than "DFF", it means the member has violated the safety requirement for deflection, and will be treated as having failed.

26. THIS VERSION DOES NOT DESIGN TAPERED POLE SECTIONS (MEMBER 1). What does this error message mean?

 I am using tapered tubular section properties in my model. When I try to design those members using the AISC code.

The AISC code currently does not have the rules for designing tubular sections which are 6 sided, 8 sided, 12 sided, etc. That is why you cannot currently design them per the AISC code.

There is a code from ASCE called the ASCE publication # 72. That document contains the rules for designing these shapes. Those rules are implemented in STAAD's transmission tower code, and if you have purchased that code, you should be able to design them.

27. I am using STAAD to do steel design per the AISC code. For 2 members with similar cross sections, one passes, the other fails. Fact is, the one which fails has almost no load on it. The other is significantly more stressed but still passes. Is something wrong in the steel design calculations that STAAD is doing?

You will notice that, for the member which failed, the cause of the failure is reported using the phrase "L/R-EXCEEDS". This means that the member has failed the slenderness check.

When STAAD performs steel design on a member per the AISC code, it adopts the following sequence :

It first sets the allowable KL/r in compression to 200 and the allowable KL/r in tension to 300.

For the member being designed, it goes through all the active load cases to see if the member is subjected to axial compression and/or axial tension.

Next, it compares the actual KL/r against the allowable KL/r. If this check results in a FAILure, the member is declared as FAILed, and design for that member is immediately terminated. The requirement to check this condition is in Section B of the AISC specifications.

If the member passes the KL/r check, only then does the program go on to do the remainder of the checks such as axial compression + bending, shear, etc.

It must be noted that failure to satisfy the KL/r check is a reflection of the slenderness of the member, not the capacity of the section to carry the loads which act on it. Even if the axial load or bending moment acting on the member is a negligible quantity, the fact is, failure to satisfy KL/r will result in the member being declared as unsafe as per the code requirement.

If you do not want the KL/r condition to be checked, you can switch off that check using a parameter called MAIN. Set MAIN to 1.0 for a specific member and it won't be checked for slenderness. See Table 2.1 of the STAAD.Pro Technical Reference Manual for details.

28. What do the following parameters mean?

NSF 0.85 ALL
BEAM 1.0 ALL
KY 1.2 ALL
RATIO 0.9 ALL
LY 18 ALL
LZ 18 ALL
CHECK CODE ALL

NSF 0.85: This parameter is called Net Section Factor. One of the criteria used in determining the capacity of a section in Axial Tension is fracture of the net section. The capacity is calculated as NSF X Gross Area X Ultimate Tensile Strength of steel in tension

BEAM 1.0: This means the design or code checking of the member will be done by determining the safety of the member at a total of 13 points along the length of the member. Those 13 points are the start, the end, and 11 intermediate points along the length. If this parameter is not set, design will be performed by checking the safety at only those locations governed by the SECTION command.

KY 1.2: The KY value is used to determine the KL/r for the Y axis -
Ky multipled by Ly divided by Ry.

RATIO 0.9: The code requires one to check the safety of a member by verifying several interaction equations for compression, bending, tension, etc. The right hand side of these equations is usually 1.0. The RATIO parameter allows one to set the right hand side to the value of the RATIO parameter, in this case 0.9.

LY 18: The LY value is used in calculating the KL/r for the Y axis -
Ky multipled by Ly divided by Ry.

LZ 18: The LZ value is used in calculating the KL/r for the Z axis -
Kz multipled by Lz divided by Rz.

CHECK CODE ALL : For ALL members, the safety of the section is determined by evaluating the ratio of applied loading to section capacity as per the code requirements.

29. When one does the AISC code check or member selection, what are the calculations the program is performing?

The checks done as per the AISC ASD 9th edition code are :

1. Slenderness - Checks for KL/r limits per Chapter B
2. Local Buckling per Chapter B
3. Axial Compression + Bending per Section H
4. Axial Tension + Bending per Section H
5. Shear per Section F

30. When I run code checking [as per BS5950] of the steel prismatic members which were defined in the User Provided Table, I get the following message in my output file:

CHECK CODE ALL

DESIGN NOT PERFORMED WITH PRISMATIC PROPERTIES
USER-TABLE MAY BE USED TO DESIGN PRISMATIC SECTIONS

The program is not designing the steel members defined as "Prismatic" in the UP Table, whereas all other members defined otherwise as Tee, Channel etc are being designed. Also I couldn't understand the meaning of the last line "User-Table may be used to design prismatic sections".

Since PRISMATIC sections by definition are those whose section shape is not one of the standard shapes like a W, C, Angle, etc., there are no readily available rules in the code to follow. Due to this reason, prismatic shapes are presently not designed per the BS code nor the ACI code.

You may get around this problem by defining the properties using the GENERAL section in a User Provided Table. For a GENERAL section, STAAD provides the means for providing dimensions of the components that are critical from the standpoint of computing allowable stresses, such as flange, web, etc. The allowable stresses for a GENERAL section are computed using the rules of a wide flange shape (I shape). As a result, the allowable stress value will be dependent on attributes such as dimensions of the cross section, length of the member, etc.

31. I am using STAAD to perform steel design on a member per the AISC ASD code. I want the column to be designed based on an unbraced length of 20 ft. I have set the UNT and UNB values to 20 ft, but STAAD appears to consider only a 10 feet length in its KL/r calculations. How do I correct this problem?

The parameters UNT and UNB are for specifying the unsupported length of the compression flange for the purpose of computing allowable stresses in bending compression.

If you want to specify the unbraced length for the purpose of computing allowable stresses in axial compression, use the parameters LY and LZ. See Table 2.1 of the STAAD.Pro Technical Reference Manual for details.

32. How do I get a design parameter, say the RATIO parameter, to be applied only to certain load cases?

You would need to use the "LOAD LIST" command. For example, if you only were interested in the 1st, 3rd and 5th load cases for the RATIO parameter you would need to write:

LOAD LIST 1 3 5
RATIO 0.5

In your input file.

33. I run the analysis of a 3-D bridge truss model and requested a CODE CHECK of the members. The results of this code check do not correspond to my hand calculation results.

The results of this code check show some very strange numbers in as far as code ratio using AISC- H1-1 formulation is concerned. Reference result output for members number 62 to 74 for example. Other ratios do not seem right either.

If you look at the AISC equation H1-1, you will find that there are 2 terms in the denominator, called

(1-fa/Fey)

and

(1-fa/Fez)

If the value of fa equals or exceeds Fey or Fez (Euler stresses), the respective terms become zero or negative, which is not a desirable event. In such a situation, STAAD replaces that negative number with the value 0.0001. The consequence of this is that, that part of the interaction equation becomes magnified by 10000, which will cause the overall value of the left hand side of equation H1-1 to increase significantly.

The above scenario is what occurs in the case of several of the members in the list 62 to 74. If you want to obtain proof of this, you may do the following. Change the value of the TRACK parameter from 1 to 2, and you will get a more detailed design output. That output will include the values of fa, Fey, Fez, etc.

To remedy the problem, you need to use a larger cross section so that "fa" becomes smaller, or use one with a smaller KL/r value so that Fey and/or Fez become larger.

34. What is the LX parameter used for?

The LX is the parameter used in calculating the axial compression capacity for flexural torsional buckling 

35. The KL/r value that STAAD reports for a single angle member does not match my hand calculation. Design is per the AISC ASD 9th edition code.

A single angle is subjected to 2 buckling modes :

1. Column buckling. This is determined using the simple expressions (Ky.Ly/ry) and (Kz.Lz/rz), where ry and rz are the radii of gyration about the principal axes.
2. Flexural torsional buckling : This mode of buckling uses an equivalent KL/r, which is computed on the basis of equation (4-4) on page 5-311 of the AISC ASD 9th edition code. Generally, this mode of failure produces a higher KL/r than the ones from the column buckling mode.

You should check whether the flexural torsional buckling mode governs in your case. The KL/r calculated for the flexural torsional mode, if it happens to the largest of the 3 values, is reported only with a TRACK 1.0 detail of output. It does not get reported for TRACK 0 or TRACK 2 level of detail of output. In other words, if you want to see the KL/r in the flexural torsional buckling mode, use the parameter TRACK 1.0.

36. What are the SSY and SSZ parameters for AISC ASD based steel design?

SSY and SSZ are terms which dictate how sidesway criteria should be used in computing the Cm coefficients. For both of them, a value of 0.0 means sidesway is present for the corresponding axis, and, a value of 1.0 means sidesway is not present for the corresponding axis.

When SSY is set to 0.0, Cmy is set to 0.85 as per page 5-55 of AISC ASD.

When SSZ is set to 0.0, Cmz is set to 0.85 as per page 5-55 of AISC ASD.

When SSY is set to 1.0, Cmy is calculated as per the equations on page 5-55 of AISC ASD.

When SSZ is set to 1.0, Cmz is calculated as per the equations on page 5-55 of AISC ASD.

If the CMY parameter is specified (and the value is a valid one), that value is used, regardless of what the value of SSY is.

If the CMZ parameter specified (and the value is a valid one), that value is used, regardless of what the value of SSZ is.

37. The KL/ry reported for a T shape does not match my hand calculations. I am designing the section per the AISC ASD 9th edition code. 

For singly symmetric shapes such as Tees and Double Angles, the KL/r value for the Y axis is calculated by STAAD using the rules for flexural torsional buckling as explained in page 3-53 of the AISC ASD manual. It is not calculated as Ky multiplied by Ly divided by ry.

38. Can you provide me with some help on how I can include deflection check as one of the criteria in steel design?

Deflection of a beam or a column can be included as one of the criteria during code checking or member selection with most steel design codes in
STAAD. The ratio of length to maximum deflection of a beam (L/d ratio) will be calculated by STAAD. STAAD will then check that quantity against the allowable limit which the user specifies under the PARAMETERS option.

What are the design parameters which control deflection check ?

1. DFF : This is the value which indicates the allowable limit for L/d ratio. For example, if a user wishes to instruct the program that L/d
cannot be smaller than 900, the DFF value should be specified as 900. The default value for DFF is 0. In other words, if this parameter is not
specified as an input, a deflection check will not be performed.

2. DJ1 and DJ2 : These 2 quantities affect the "L" as well as the "d" in the calculated L/d ratio. They represent node numbers that form the basis for determining L and d.

By default, DJ1 and DJ2 are the start and end nodes of the member for which the design is being performed, and "L" is the length of the member, namely, the distance between DJ1 and DJ2. However, if that member is a component segment of a larger beam, and the user wishes to instruct STAAD that the end nodes of the larger beam are to be used in the evaluation of L/d, then
he/she may input DJ1 and DJ2 as the end nodes of the larger beam. Also, the "d" in L/d is calculated as the maximum local displacement of the member between the points DJ1 and DJ2. The definition of local displacement is available in Section 5.42 of the STAADPro Technical Reference Manual, as well as in Example problem # 13 in the STAADPro Examples Manual.

A pictorial representation of DJ1 and DJ2, as well additional information on these topics is available under the "Notes" section following Table 2.1 in Section 2.8 of the STAADPro Technical Reference Manual.

What are the results one gets from STAAD for the deflection check?

If the steel design parameter called TRACK is set to 2.0, the L/d ratio calculated for the member can be obtained in the STAAD output file. The value is reported against the term "dff". Notice that the expression is in lower-case letters as opposed to the upper-case "DFF" which stands for the allowable L/d.

If "dff" is smaller than "DFF", that means that the displacements exceeds the allowable limit, and that leads to the unity check exceeding 1.0. This is usually a cause for failure, unless the RATIO parameter is set to a value higher than 1.0. If "DFF" divided by "dff" exceeds the value of the parameter RATIO, the member is assumed to have failed the deflection check.

What are the limitations of this check?

Since the "d" in L/d is the local deflection, this approach is not applicable in the case of a member which deflects like a cantilever beam.
That is because, the maximum deflection in a cantilever beam is the absolute quantity at the free end, rather than the local deflection. Check whether STAAD offers a parameter called CAN for the code that you are designing to. If it is available, set CAN to 1 for a cantilever style deflection check.

Since the deflection which is checked is a span deflection and not a node displacement, the check is also not useful if the user wishes to limit story drift on a structure.

39. In the output for steel design, what does the term "dff" represent?

"dff" is the value of actual length divided by local deflection. The actual length value is the distance between the nodes DJ1 and DJ2 which default to the actual end nodes of the member. The deflection used is the maximum local deflection between the points DJ1 and DJ2. You can get the Max. Local Displacement value by looking at the output of the PRINT SECTION DISPLACEMENT command. The definition of DFF, DJ1 and DJ2 may be found in Table 2.1 of the Technical Reference Manual for STAAD/Pro.The word PRISMATIC is meant to indicate a section of any arbitrary shape. But the AISC code does not provide guidelines for design of arbitrary shapes.
Section capacities are dependent upon aspects such as the width to thickness ratio of flanges and webs, lateral torsional buckling etc. From that standpoint, using an allowable stress of 0.6Fy for PRISMATIC sections was not always conservative. 

40. In STAAD-III, I was able to get a steel design for members defined using the PRISMATIC property attribute per the AISC ASD code. I cannot do this in STAAD/Pro. Why?

In the earlier versions of STAAD, the code check for prismatic sections was done using allowable stresses which are arbitrarily chosen as 0.6 Fy. However, this assumption of 0.6Fy was not based on any code specific requirements.

The word PRISMATIC is meant to indicate a section of any arbitrary shape. But the AISC code does not provide guidelines for design of arbitrary shapes. Section capacities are dependent upon aspects such as the width to thickness ratio of flanges and webs, lateral torsional buckling etc. From that standpoint, using an allowable stress of 0.6Fy for PRISMATIC sections was not always conservative.

A way around this limitation (lack of specific guidelines) would have been to use the rules of a known shape, such as a Wide Flange, for designing prismatic shapes. That would require knowledge of equivalent flange and web dimensions. When the properties are defined using the PRISMATIC option, there is no means to convey information such as dimensions of flanges or webs to the STAAD design facility. Hence, the design of PRISMATIC shapes is not supported in STAAD/Pro.

You may get around this problem by defining the properties using the GENERAL section in a User Provided Table. For a GENERAL section, STAAD provides the means for providing dimensions of the components that are critical from the standpoint of computing allowable stresses. The allowable stresses for a GENERAL section are computed using the rules of a wide flange shape (I shape). As a result, the allowable stress value will be dependent on attributes such as dimensions of the cross section, length of the member, etc.

41. In the context of design, what is meant by the term Ratio?

In steel design, the Pass/Fail status of a member is determined according to various conditions. According to most design codes, the member has to be checked for failure against axial compression and axial tension, slenderness, compressive & tensile stresses caused by axial compressive force + bending moments, failure caused by shear stresses, etc. For each of these conditions, determination of whether the member is safe or unsafe is done by checking whether the actual values due to the loading exceed or are less than the allowable values. The amount by which the member is stressed for each of these conditions is quantified in the form of the Ratio. For example, take the case of equation H1-1 of Section H of the AISC-89 specifications. The number obtained by computing the left hand side of that equation is the Ratio corresponding to that equation.

42. I have multiple sets of design in the same STAAD file and I am only able to see the results for the final set in the Postprocessing mode (GUI). How can I view the results for all design sets in the GUI ?

The postprocessing Beam >Unity Check page can report the design results only for the final set of design. This is a limitation in STAAD.Pro as the program architecture does not allow that results of multiple design sets to be made available at the same time graphically. The analysis output file is the only place where you can view results for all design sets. The only way to view the results of a previous design cycle graphically is 

1. to go to the editor and comment out the subsequent design sets and rerun the analysis
2. reverse the order for the design data blocks so that the set, for which the GUI data is needed, becomes the last set.     

43. How is the shear stress calculated in STAAD.Pro for AISC design code ? 

The shear stress calculated by STAAD is the maximum shear stress by default which is based on the standard formula VQ/Ib, where

V = Shear force

Q = Moment of area of the part of the cross section that
is above ( or below ) the plane where shear stress is being calculated, about
the neutral axis

I = Moment of Inertia

b= Width of the section at the plane where the stress is
being calculated

So the term Ib/Q is reported as the shear area that corresponds to this shear stress calculation.

If required one can get STAAD to calculate the average shear stress instead of the maximum. There is a SHE design parameter that can be used to influence how STAAD calculates the shear stress. When the parameter is set to 0 ( default ), stress is calculated as mentioned above. However when this parameter is set to 1, average shear stress will be calculated based on the formula V/Ay (or Az ) where Ay or Az are the shear area for the cross section.  

44. Do you have a plan that STAAD.Pro implements AISI 2007 edition?

AISI 2007 code is being developed, but as part of the STAAD(X) project rather than STAAD.Pro. It should be released in mid next year (2014).

45. A structure that I'm working on I have a 11.6m beam which supports transverse beams and bracing. How can I determine the overall deflection of the 11.6 m beam and check if it is complying with the L/500 criteria?

There are a couple of ways to handle this. One is during the design phase and another is during the analysis phase.

Check during design phase

To ensure that beams are checked appropriately for deflection, using the physical member length as opposed to the length of the analytical segments, please refer to the Note 2 under section 2.4.1.2 ( Design Parameters) from the Technical Reference Manual ( can be accessed through Help > Contents > Technical Reference ) which explains how the design parameters like DJ1, DJ2 and DFF can be used to check deflection for the physical member. In your case, you would specify DFF as 500 for the beam to be checked against an allowable deflection limit of L/500.

Checking during analysis phase

If you are not planning to go for design and would just like to check the deflection based on analysis results, you may define the entire beam as a physical member (PMEMBER). After analysis you will then be able to double click on the physical member ( ensure that your selection cursor is the physical member cursor ) and see the local deflection for the entire physical member.   

46. I am changing the K and FYLD parameters for some members but the values reported in the design output indicate that those did not change. Why ?

For the values to be accepted by the software, you need to ensure that these parameters are added to the input file before the CHECK CODE or SELECT command. For example if you need to specify FYLD as 50 ksi for members 1 and 2, you should have the commands in the following order

PARAMETER 1
CODE ...
...
FYLD 50 MEMB 1 2
CHECK CODE ALL

If you add the parameters after the CHECK CODE as shown next, the design would not consider those

PARAMETER 1
CODE ...
...
CHECK CODE ALL
FYLD 50 MEMB 1 2
...

47. Can the CHECK CODE command be applied for a created group of members?

Yes, the design (CODE CHECK) can be performed for some specific group of members. Let's say we have a group called TEST which was created by going to Tools -> Create New Group. In order to perform a design for the members which are defined in that group only, you need to go to the STAAD Editor (Edit -> Edit Input Command File) and find a CHECK CODE ALL line (if that command is already added). This command line should be changed to line CHECK CODE MEMB _TEST.

48. I have done a buckling analysis and can see the buckling factors. However when I attempt to do a steel design, all members fail. Why ?

Buckling analysis is only to be used for finding out the buckling factor. The purpose of the analysis is to find out the load at which the structure starts to buckle. This load is obtained by multiplying the applied loading by a buckling factor that is reported by the analysis. The displacement/support reactions/ member forces reported by the STAAD.Pro basic solver from a buckling analysis, represents the values at the near buckling load. One should not attempt to design the structure based on these forces. For member design, one should always use a PERFORM ANALYSIS or any form of second order analysis like PDELTA. 

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!

Member End Forces

Member end forces and moments in the member result from loads applied to the structure. These forces are in the local member coordinate system.

The end forces (FX, FY and FZ) will be positive if the forces are in the positive local axis. The following figure shows the positive member end forces.

The member end moments (MX, MY and MZ) follow the right hand rule. If the right hand thumb points the positive local axis, then the fingers point in the direction of the positive moment. The following figure shows the positive member end moments.

Joint Equilibrium

The joint equilibrium should be checked in three planes (XY, YZ and ZX plane). For each plane, the axis which is perpendicular to that plane is considered for the joint equilibrium check. The summation of forces along that axis and moments about that axis should be zero.

Example:

In this example, the following plane is considered - member 31501, 31518, 1139 and 1140 is on that plane and member 1032 is perpendicular to this plane. 

Force Equilibrium:

The following forces are considered —

Positive FZ force at node 1015 for member 1139 : 0.02 kN

Negative FZ force at node 1015 for member 31501 : -0.482 kN

Positive FZ force at node 1015 for member 1140 : -0.675 kN

Negative FZ force at node 1015 for member 31518 : 0.797 kN

Negative FX force at node 1015 for member 1032 : 0.34 kN

So the summation of force along the axis perpendicular to the plane is: 0.02+(-0.482)+(-0.675)+0.797+0.34 = 0

Moment Equilibrium:

The moments are acting at the member end. To check the joint equilibrium, the reactions at node 1015 is considered.

MZ force at node 1015 for member 1139 : 4.668 kN-m

MZ force at node 1015 for member 31501 : 45.66 kN-m

MZ force at node 1015 for member 1140 : -116.441 kN-m

MZ force at node 1015 for member 31518 : 66.11 kN-m

MX force at node 1015 for member 1032 : 0.003 kN-m

Summation of moment about the axis perpendicular to the plane is: 4.668+46.66+(-116.441)+66.11+0.003 = 0

Error or Warning Message

After creating a new model, the following error occurs when attempting to open RAM Modeler:

"Unable to find the requested .NET framework data provider. It may not be installed."

Explanation

A dependency named Microsoft SQL Server Compact Edition is not installed properly.

How to Avoid

Microsoft SQL Server Compact Edition is not installed correctly. Please perform the following steps:

1. Uninstall it from the Add or Remove Programs (Windows XP) or Programs and Features (Windows Vista/7/8) control panel.
   If running RAM Structural System 14.06.xx or later: Remove either Microsoft SQL Server Compact 4.0 or Microsoft SQL Server Compact 4.0 x64.
   If running RAM Structural System 14.05.xx or earlier: Remove Microsoft SQL Server 2005 Compact Edition.
2. Reinstall the component.
   If running RAM Structural System 14.03.xx or later: Open the RAM Structural System installer (e.g. rss14030000en.exe or ramm14050300en.exe), and click the Install button next to Microsoft SQL Server Compact Edition.
   If running RAM Structural System 14.02.xx or earlier: Run SQLServerCE31-EN.msi located in RAM Structural System\Prog.

See Also

[[SELECTsupport TechNotes And FAQs]]

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Error Messages

Angle Between AB and AC Too Small

Windows Topics

Where Are My Toolbars?

Toolbars and Extra Buttons

How To Initialize Microstran Configuration Settings

Dual Monitor Operation

Windows Terminology

Exchanging Data Between Microstran and a Spreadsheet

Hardlock and Windows XP

Graphical Input

Extrusion

What's the Use of the Grid When Most Nodes Are Not on a Grid Point?

How Can I Input Nodes that Are Not on a Grid Point?

Load Sub-division

Restraints and Releases

What's the Difference Between Restraints and Releases?

Why Are There Different Conventions for Restraints and Releases?

Why Are "1" and "0" Used Instead of "F" and "R" for Restraints and Releases?

Modelling

What's the Difference Between a Constraint and a Restraint?

Master-Slave Constraints

Instability and Ill-Conditioning

Common Modelling Problems

Plastic Analysis of Frames

Analysis of Tilt-Up Panels

Design of Fall Arrest Systems

Non-Linear Analysis

Why Do I Have to Select Which Load Cases Are Analysed?

Saving Time with Non-Linear Analysis

Steel Design

Adding a Section to the Steel Library

Restraints for Steel Design

How Can Normal Grade Be Stronger Than High Grade

Angles

Dynamic Analysis

What Does Microstran Dynamic Analysis Do?

What's the Difference Between Lumped  and Consistent Mass?

What is Response Spectrum Analysis?

Earthquake Analysis to AS 1170.4

Earthquake Analysis to NZS 4203

Elastic Critical Load Analysis

Why Does ECL Analysis Give Such High k Factors?

What Effective Length Factor Should I Use for Design?

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What floor-to-floor height should I enter in the story data?

Whatever story height you enter into RAM Modeler, that is where the centerline of the frame beams will fall in the finite element model and vertical braces always connect to a work point at the beam and column centerlines. This is done for simplicity in the finite element analysis.

For drift sensitive structures, using a first story height that is equal to the distance from the ground level (or foundation level) up to the top of steel - average frame beam depth / 2 is probably the most accurate modeling (see "Alternate Story El." below). But using a distance from ground level to beam top of steel (a.k.a. deck bearing) is more common practice and is conservative in most aspects (see "Common Story El." below).

The common story approach is also used when the RAM SS 3D model is exported to ISM. In the ISM model the beam locations are established relative to the story datum based on the following rules:

• Non composite deck – top of beam, deck bearing at story datum
• Composite deck – top of beam, deck bearing at story datum
• Concrete slab – top of slab at story datum

Keep in mind, story height can also affect the following calculations:

• Calculated wind exposure (and Kz factors)
• "h" in the vertical distribution of seismic loads calculation (wi*hi/Sum (wi*hi))
• Overturning moment (related to lateral force times story height)
• Unbraced length for columns
• Slope angle and length of braces
• Material takeoff quantities
• And the elevation of the beams shown in the 3D view, or exported out to Revit, ISM, or dxf, which are all artificially adjusted to show all beams with top of steel at the story height.

How can I model a continuous beam?

In Ram Structural System, the framing must all be determinate, so multi-span indeterminate framing is not directly possible. There are two approaches to modeling and designing continuous beams. 

The first is to model each span as a lateral beam. use the same size for each span and be sure to assign the ends to be fixed. The supporting columns also need to be lateral, but they may be pinned (in the plane of the framing). To see the accurate member forces or steel design of the beams, use Ram Frame analysis and the Steel Standard Provisions respectively.

Alternatively, for those that do not have Ram Frame, the system can be approximated using a cantilever and suspended span approach. In other words, model one span normally and add a cantilever extension into the second bay. Then add a suspended span from the end of the cantilever to the third support (or add a cantilever beam in every other bay for continuous beams more then 2 spans long). The length of the cantilever is important here since it dictates the inflection point or point of zero moment.

Can a beam cantilever directly from a support with no back-span?

Yes, the option to create a stub cantilever or beam with a single support was added in version 14.02.  The following applies to prior versions:

In the RAM Modeler, a cantilever can only be created by extending a simple-span beam over its support. When the building requires a stub cantilever which cantilevers directly from the column, then a special modeling trick can be employed.

In order to get an accurate analysis and design of that cantilever beam, requires the use of RAM Frame. Start by modeling the column which will support this cantilever. Make that column lateral and make sure that it is supported by other lateral columns if this is not the lowest level. Next add a dummy column at the point where the cantilever stops. Make this dummy column out of “Other” material and assign it a very small “E” value (e.g. 1). Then assign that column a section size under Property table – Other column sections that is very small (e.g. 1” square).

Next model in the cantilever as a simple, lateral beam from the real column to the dummy column. At the end where this beam frames to the real column be sure to assign a fixed end condition so that moments can develop. You will also need to make sure that the column is capable of taking moment at the top.

The finished section of the model should look something like the figure below. Note – the analysis results from RAM Frame will provide an accurate design, but the gravity beam and column modules will not recognize that this dummy column is too weak to take load. Only the finite element analysis of RAM Frame is capable of that.

How can I create a sloping floor or roof?

There are some basic limitations to what you can model with RAM Structural System, so it may not be possible to model some structures perfectly, but you can usually get close. The following guidelines should help

• Every beam must have exactly two supports, never 1 or 3, and those supports must be on the same level type. So you can't directly model a bent beam forming a gable unless there is a support at the peak.
• You must be able to model the structure as a flat (wedding cake) type structure first, then create the slopes by changing column (and wall) elevations.
• Any time you have a step (two beams framing into the same support at different elevations), two levels types and two stories are required and the higher beam must be on the higher story.
• You can raise or lower a column (or wall) using the Layout - Column - Modify elevation command and thus slope beams that connect to it. If you want to lower the column more than the story height, then you must also lower the same column on the next lower story. Think of the column like a string with beads on it at each story. As you modify the elevation you are lowering the bead, but you cannot cross another bead. In the end, the beads must be at least 0.1’ apart (more separation is preferred).

Other things to note:

• You can have a rigid diaphragm that is sloped, but in RAM Frame this is treated as a horizontal diaphragm. We don't analyze sloped rigid diaphragms. Furthermore, if your structure is subject to trust, diaphragms should be turned off at least while investigating gravity loads. Using a sloped semi-rigid diaphragm is an alternative.
• The gravity steel and concrete beam design will not include any effects of axial forces.

I modeled a roof with multiple slopes, but in the 3D view the deck is a single sloped plane shooting up.  How do I fix this?

Starting in version 14.0, the program will display the surface of the deck in 3D.

For a sloping deck to function correctly in this regard, the deck must be input using a separate polygon for each sloping surface. In other words, for a gable roof, two deck polygons should be defined, one for each side or slope of the roof.  A whole-floor application of the deck is no longer sufficient.

It is suggested to snap to the beam end points when defining these decks, since the beam end points have exact elevations which are derived from the supporting column or wall elevations. Here's a better way to lay out the deck polygons for the model illustrated above:

Even slight imprecision in the support elevations (i.e. warping of the deck) can cause this anomaly in 3D.

The analysis results will only be affected if the warped deck is part of a semirigid diaphragm in RAM Frame or is defined as a two-way deck.

How can I model a 2 story brace, or one that skips a level?

When a brace needs to skip a level use Layout - brace - Add Special and follow the prompts at the bottom left.

For details on how these braces effect frame story shear reporting, please reference [[RAM Frame - Building and Frame Story Shear]].

I have a brace in 3D that does not appear in any elevation view. How can I delete it?

There are two ways to remove rogue braces that are no longer in an elevation view that can be selected.

1. If the braces do not connect to any frame members at either end, then an integrated data check can be performed and the following message will appear: "Some Braces do not attach to Nodes. Do you want them deleted?". Click "Yes" to have them removed. Note – if the brace is connected to a lateral member at one end, but not the other, this message will not appear, so you may need to make some supporting beams or column gravity temporarily.
2. Delete and re-enter the story data for this particular level. This will remove all braces at that level.
    

How do I model a transfer girder, or a column setting on a beam?

On the upper story level model the column as a standard column (not a hanger).

On the lower level model the beam passing through the location of the column above. This could also be a beam cantilever.

Use Reference layout types (under the options menu) or construction grids to aid in the alignment of the column and beam below.

I have a column that supports the roof, but does not support anything at the lower level. Do I have to model the column on both layouts in RAM Modeler?

Think of the RAM SS Layout type like a section through the whole structure. Any columns that are cut by the section should be modeled on that layout typically. Don't worry, the program will design the column for the correct, longer unbraced length so long as there are no beams (or optionally decks) at the intermediate story to brace the column.

There is one alternative, however. If the column is only modeled on the Roof, and not modeled on the lower level at all, then you can add a foundation under that column and lower the foundation to stretch the column to the full height. This approach can be helpful in cases where the column is sloped and the story heights are not constant making it hard to determine the exact bottom offset to keep the two-story column in one straight line.

Why am I unable to copy information or import a DXF into a layout?

The Copy and Import from DXF features (RAM Modeler - Layout - Type menu) are only active for layout types that contain no information. These commands are deactivated in RAM Modeler even if the layout contains only grids and no other objects. To use either command, create a new layout and then use the copy or import features before any other information is defined on the layout.

How Do I Model Grade Beams?

Although there is currently no direct way to model grade beams in RAM Structural System, they can be simulated by modeling concrete beams and designed in RAM Concrete. These basic steps produce satisfactory results for most configurations.

1. Model a grade level that contains the concrete grade beams supported by columns. The top of the columns should be pinned and the bottom fixed.
2. Model a slab edge on the grade beam level and assign a noncomposite deck with no selfweight. This is necessary so that there is a diaphragm present on the level in RAM Frame.
3. Add the grade level to your story data.
4. In RAM Frame, set the ground level to the grade level.
5. Run the RAM Frame analysis and RAM Concrete Beam design.

By creating a rigid diaphragm at the grade level with the nodes at the grade beam - column intersections to it, translation is restrained when the ground level is set to the grade level. Therefore, no shear will exist in the column stubs. Since the top of the column stubs are pinned, no moment will be developed in the column stub below the grade beams. Spread footings or pile caps can be modeled at the column stub locations. The foundation loads will only be vertical forces.

There are a couple of important things to note. First, automatic calculation of effective length factors may be inaccurate for this procedure. No boundary condition is assumed at the lower node of the column above the grade beam level. Therefore, the G value for the lower node is a function of the column and grade beam stiffness in the direction being considered. If this is not an accurate assumption, the effective length factor should be explicitly defined. Second, don't specify a story height on the grade beam level that is too small. Using an extremely small story height is not necessary because there will be no translation of the grade beam level and only vertical forces in the stub columns. The only ramification of using a larger story height is an increased selfweight for the stub columns. If you use too small of a story height you might produce a poor mesh if lateral walls are modeled on the grade beam level.

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!

This page contains a list of new Properties functions.

The following OpenSTAAD function retrieves the member specification of a specified member. 

Property.GetMemberSpecCode varMembNo, SpecCode

Where:

varMembNo

A long variable which stores the member number.

SpecCode

An integer variable that holds the member specification. The spcificatiion number should represnt the following member spcification.

0 = Member Truss

1 = Member Tension

2 = Member Compression

3 = Member Cable

4 = Member Joist

-1 = No member specification assigned

VB Example

Dim member As Long

Dim spec as Integer

objopenstaad.Property.GetMemberSpecCode member, spec

Everything Needed for Steel Connection Design

RAM Connection can check or design connections in seconds. Whether you design connections or need to check connections designed by the shop, RAM Connection is the software for you. In just one low-cost package, you get both AISC ASD and LRFD as well as BS5950-1 connection design and optimization for shear and moment connections, braced frame connections, and column and beam splices. Through its seamless integration with the [[RAM Structural System]], [[RAM Elements]], and [[STAAD.Pro]], RAM Connection raises the bar to a new level of productivity. All data regarding member sizes, joint geometry, and forces are transferred directly from either the RAM Structural System, RAM Elements, or STAAD.Pro to RAM Connection.

Flexibility built-in

Skews, slopes, or both are handled with ease-and if you're using RAM Connection integrated with RAM Steel, RAM Frame, RAM Elements, or STAAD.Pro then beam, column, and brace configurations are done automatically for you in seconds. Got a change? RAM Connection easily allows you to revise and modify single as well as groups of connections for easy and comprehensive solutions for your customers.

RAM Connection allows you to easily enter your own connection tables and rules-of-thumb to conform to your office standards. You can also simply choose from our large database of predefined connections to meet your design needs.

Advantages

Easy to use

RAM Connection is easy to use even when you just start working with it. Connections can be checked or designed in a matter of minutes!

Comprehensive connection types

RAM Connection is comprehensive, with all types of steel connection design for the U.S. codes and U.K. codes. Connection types include shear, moment, splice, and brace connections:

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 (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)

Stand alone or fully integrated

RAM Connection can be used as a stand alone program or fully integrated with [[RAM Structural System]], [[RAM Elements]], and [[STAAD.Pro]]. The integration allows transfer of design force from your structural model and saves hours of time on each project.

Rapid changes

Single or sweeping changes to your designs can be made with RAM Connection. When your project calls for a preferred connection detail you can quickly specify this in RAM Connection, designing connections quickly.

Safe design

RAM Connection can group sets of connections to keep a project's connections uniform. This will allow you to optimize your model and provide an efficient yet safe design.

Fast, error-free design

RAM Connection provides easy to use CAD details of designed connections which can save hours of detailing time and also reduce errors in transfer of information.

Support for seismic design

RAM Connection deals with the seismic design connection requirements, which can be time consuming and difficult to keep up with.

Fast connection design and review

RAM Connection is the fastest way to review and check connection details and shop drawings. Design a connection from the beginning or review an existing one in minutes.

Comprehensive reporting

Comprehensive and thorough reports are provided by RAM Connection. These reports are easy to understand and can be used directly in your calculation submissions for building departments and peer reviews.

Best in class technical support

Bentley provides prompt and helpful technical support-the industry's most responsive. While other vendors may take days to respond to technical questions, and some vendors do not even provide technical support via telephone, our goal is to provide expert advice in hours, to help make sure you continue to be productive with our software tools.

Product Tour

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 Related Links

Related products: [[RAM Elements]], [[RAM Structural System]], [[STAAD.Pro]]

I've upgraded to STAAD.Pro V8i Select series 5 (SS5) and while analyzing I get the message:

"Copy/protection device system does not support BS5950-2000(British/steel) design code. The design will not be performed." I have not seen this in the previous version of the program.

From  STAAD.Pro V8i Select series 5 (SS5) Build #20.07.10.41, the UK codes have been repackaged as below. Please contact your account manager to get this code pack included in your contract. If you need to use the code urgently, you may continue using the code in  SS4 version. Both SS4 and SS5 can be installed on the same workstation.

UK Super Code:-

Steel

Concrete

NOTE:

The same has happened to all European Design codes. EN 1993-1-1:2005 (with all National Annexes), EN 1992-1-1:1991 and design codes of Denmark, Finland, France, Germany, Netherlands, Norway, Russia, Spain and Sweden are all included in the ECC Super Codes license package in STAAD.Pro SELECTseries 5.

A more detailed explanation can be found in this Blog post:
Changes to Licensing in STAAD.Pro V8i SS5- Part 2, European Super Codes

The design codes are not listed in the start-up page of STAAD.Pro SELECTseries 5. How the design codes should be selected?

Starting from STAAD.Pro V8i SELECTseries 5 (build 20.07.10.41), you do not need to check out design codes anymore. STAAD.Pro now utilizes Bentley's Trust Licensing as most other Bentley's programs do. This means that you can use any design codes now even without having a license for it. When you will run the analysis (including the selected design code) a usage data will be sent to the SELECTserver periodically for billing at a later time for your convenience.

You can find much more information about Trust Licensing in the following Be Communities posts:

Changes to Licensing in STAAD.Pro V8i SS5 - Part 1, Trust Licensing

About trust licensing

Trust licensing basics

Understanding, Monitoring and Managing Usages