How can I assign a member to be tension-only?

Go to the Members tab of the spreadsheet input, and go to the hinges sheet. The first field is for "Axial rigidity". Set this to tension only by selecting that option from the drop down list, or use the Ribbon menu tool "Tension only" once you have only the desired members selected.

Why is my tension-only brace failing in bending?

There are three typical reasons why a tension-only member will induce bending.

1. If the member ends are fixed, a tension-only member can still develop and end moment. Tension-only members are typically hinged at both ends in both M3 and M2 axis, if not also torsion.
2. If self-weight loads are applied this will cause the member to bend or sag under its own self-weight. To alleviate this issue we suggest using a weightless, zero density material for tension only member. An "A36 weightless" material is provided out of the box for this purpose.
3. If the tension-only member intersects other members and the Finite Element analysis option to "Add intermediate nodes at member intersections" is checked, then there will be intermediate points of connection (without hinges) leading to force transfer and potentially bending. We suggest not using this option for models with tension-only braces. If there are other places where you really want joints at member intersections, manually segment those portions using Process - Segment selection.

Why are my combined forces not equal to the sum of the load case forces?

When you run a P-Delta analysis, or a tension-only analysis, or compression-only analysis, each combination is solved directly. We do not use addition, or superposition, to calculate combined effects since a member that might not be in compression due to one load may be in compression due to that same load combined with another.

Under Process - Analysis - Load Conditions tab the user can select which cases or combinations to include.

See Also

RAM Instability In Finite Element Analysis

RAM Frame - Tension Only [FAQ]

Ram Elements Load Combos [FAQ]

Product TechNotes and FAQs

Structural Product TechNotes And FAQs

What is the load combination "Type" for?

In RAM Elements (and Ram Connection), every load combination is given a type that determines when the load combination is utilized. The figure below illustrates how several different types of combos could be used in a single file.

When I analyze the model all the combinations are grayed out. Why?

On the Analysis tab of the Process – Analyze model dialog box, the user indicates if second order analysis will be considered. This is required when using tension-only members or compression-only springs, but may be turned on for any model.

Whenever a second order analysis is performed, the program individually analyzes each selected load case and combination that is checked on the Condition tab.

If second order analysis is NOT performed, then the program only analyzes the selected load cases. The results for all combinations are generated using the principal of superposition, so the user can no longer uncheck individual combos.

Furthermore, if the user opts not to analyze certain load cases, any combinations including those load cases will not have any results available.

When I try to optimize including deflections, I cannot select any load combos. Why?

The program uses "Service" or "Service-Steel" type load combinations for checking beam deflections. If a model has only "Design" or "Design-Steel" combinations and no service combinations, this feature will not be available. Add at least one service combo (e.g. 1.0 DL + 1.0 LL) to access this feature.

When I try to enter loads on members or nodes I can't because the spreadsheet is grayed out. Why?

In the lower right hand corner of the program window is the Current Load Condition selection. If the selection is a load case, then you can enter loads for that load case on members, nodes, shells etc. If that selection is a load combination then you can view, but not edit or add to the existing loads.

Change the condition to a valid load case in order to add loads. 

Load cases that are associated with dynamic response spectrum analysis should not have any static loads at all. 

Can I copy and paste load case or load combinations from one file to another?

Yes, you can literally copy the data (ctrl+C) from one file to paste (ctrl+V) into another. You can also copy the data and paste into Excel for future use in another file. Note, the list box data like "Type" will be converted into integers during this process.

You can also save your load conditions from a complete model and then recover those load conditions in a new file. Those options, as well as the option for generating load combinations, are all under the Home Ribbon Menu - Load Conditions group.

When I use Skip Loading in the Continuous Beam module, why does the program combine all the load patterns into one (and over design the beam)?

Do I need to include load combinations with negative factors on lateral loads?

Program generated load combinations only include positive factors on lateral wind or seismic loads. If the model is subject to equal magnitude, opposite direction lateral loads, then additional combinations should be manually added using negative load factors on those load cases. If the opposite direction lateral loads should be applied to different members, as is often the case with wind load, then an additional negative direction Load Case should be added instead.

This is contrary to the behavior in RAM Structural System, where rigid diaphragms and linear-elastic braces are the norm.

See Also

[[Ram Elements - Tension Only Members]]

How does changing the ground level affect restraints?

The ground level for Frame analysis can be set through Criteria - Ground level. 

The default is for the model base to be the ground level. This is the bottom of the lowest story in the model story data.

The program will automatically provide a support point or restraint at the base level under every lateral column and wall. Additionally, where lateral columns or walls terminate on a higher story with nothing below them, additional support points are provided.

When you set an upper level to be the Ground Level, the program applies lateral restraint in the global X and Y directions to the diaphragm (or multiple diaphragms) at that story. This is analogous to having a vertical roller support on all the nodes attached to those diaphragms. Nodes that are disconnected from the diaphragm are no longer constrained by any ground level restraint. Any subterranean story below the ground level is also treated the same way.

In models with the ground level above the model base, overturning of the structure will be partially resisted by force couples formed by reactions at the ground level and level below (aka prying action). These reactions result in shear reversals and high shear forces in columns and walls on the subterranean levels.

How does changing the ground level affect wind and seismic loads?

In the calculation of wind and seismic loads, the program assumes the ground level as set under Criteria - Ground level is the zero elevation. All heights using in calculating wind pressures or seismic load distribution are measured up from this ground story. 

Can I have the loads calculated based on an elevated ground level, but not have the ground level restrained?

Not automatically, but "User Defined Story Forces" are the alternative where the diaphragms are rigid or semi-rigid. We usually recommend to run the model first with an elevated ground level. Then print the Loads and Applied Forces report. Next, create new wind (or seismic) load cases, using the "User Defined Story Force" option under Loads – Load Cases, that are based on that output and delete the original program calculated loads. Finally, reset the ground level to the base.

See Also

RAM Frame - Building and Frame Story Shear

RAM Frame - Wind Loads [FAQ]

RAM Frame - Seismic Loads [FAQ]

How can I assign a member to be tension only?

Any vertical or horizontal brace member may be assigned to be tension-only. The assignment is made in RAM Frame using the Assign menu - Braces - Tension-Only command. Assigning a brace to be tension only does not automatically release the brace for moments or torsion, however. That is controlled through the Assign menu - Braces - Fixity command.

If no assignment is made, then the braces will resist tension and compression elastically. Beams, columns and walls are always capable of resisting compression.

How are reverse direction lateral loads handled when using tension-only members?

When defining program generated lateral loads, like wind or seismic loads, there is an option to "Generate Additional Load Cases for Analysis with Tension-Only Members" that should be checked when the model includes any tension-only braces. Using this option leads to a load case in the positive direction, say west to east, and another load case in the negative direction, east to west.  For each of these load cases, different members may be active in resisting the load so it's important to perform a separate finite element analysis of each direction. 

If the model includes tension-only braces, but this option is not checked then a warning is generated. 

When all the braces are tension and compression braces, then the whole model in linear-elastic and the analysis can be simplified by only analyzing the positive direction loads and then using both positive and negative terms on lateral loads in load combinations to account for reversibility.

Note, for models with user defined loads or nodal loads the same rules apply; if there are any tension-only braces in the model, then user loads should be created for both directions. 

How can I resolve an error, "tension-only member in compression"?

In the steel design mode, you might see the warning "T-O in comp" on the View/Update dialog box or "Member with Tension Only Shape is in Compression" on the design report. There are some cross sections that the RAM Frame Steel postprocessor can only check when they are in tension. If a single angle, rod or flat bar goes into compression, then the design will always give these warnings. You can manually check the design of such using the member force envelope results.

The same error message, "T-O in comp", can also occur for a member that is defined as a tension-only brace if there are custom load combinations utilizing negative terms on lateral load cases. It's important for models with any tension-only braces that the lateral loads be applied in all directions so that the load combos can use positive terms exclusively.

Why is my tension-only brace failing in compression?

If a brace that was specifically assigned to be tension only is going into compression, that usually indicates a problem with the load combinations. For models with tension only members, the load combinations should never include negative terms in any load combinations (generated or custom). If there is a combo with a negative term, the resulting brace force could be compression and the warnings above will occur.

Consequently, any model with tension only members requires one lateral load case in the positive direction and another load case in the opposite direction if all the braces are to be correctly evaluated. For program generated loads, there is a check box for "Generate Additional Load Cases for Analysis with Tension-Only Members" that can be selected to do this automatically, but for user defined story forces or nodal loads, an additional case for the reverse direction must be manually input.

How is a tension only brace considered during dynamic analysis?

For any dynamic, response spectrum load case, all braces are assumed to be 50% effective. This generally accounts for an appropriate amount of stiffness for a symmetrically braced frame, but does not prevent the braces from showing compression results. This approach is also used for the eigensolution.

Why am I getting large deflections under gravity loads?

In the RAM Frame analysis, braces that are designated to be tension-only are completely ignored during the analysis of the gravity load cases (dead, live, roof and snow). For the evaluation of lateral loads the program uses an iterative approach to determine which braces are in tension under each lateral load case. Then the program superimposes the results based on the defined combinations in order to code check the braces.

In structures where all the braces are tension-only, a global instability can often result for gravity loads. If you get an instability warning or if the deflections are significantly large under gravity load cases there are several things you can do.

1. Simply ignore the gravity load deflections. For the purpose of evaluating deflections, use the lateral load cases alone (uncombined). So long as there are no significant shears or moments developing in the other lateral members due to the drift, there is really no harm in this.
2. Provide a secondary system to give the structure some lateral stiffness even when the tension-only braces are ignored. Typically, this is a matter of fixing the columns all the way to the base. If a fixed base condition is too stiff, try adding a rotational foundation spring at the base of the columns to reduce the lateral stiffness.
3. Remove the tension-only assignment from the braces altogether. In this case, the braces can typically be hand-designed for tension equal to two times the maximum (or minimum) axial force from any combination (obtained from a member force envelope report). This approach can alter the load path affecting column and foundation design however.  

An enhancement was added in RAM Structural System v14.06, which should resolve the problem with large displacements and instability errors. Beginning with this version, P-Delta effects will not be included when analyzing gravity load cases with the special tension-only analysis. This is a reasonable implementation since in virtually all cases the P-delta moments due to lateral sway caused by gravity loads is extremely small. P-Delta effects will still be considered with the lateral load cases. More on this can be found in the v14.06 release notes, which are located here: V14.6 Release Notes.

Starting in version 14.07 another option was added to the RAM Frame General criteria for Buckling Restrained Braced Frames (BRB). If the option to "Exclude Buckling Restrained Braces from the Gravity Load Case Analysis" is checked, the same problem noted above for tension-only braces may occur.

See Also

RAM Instability In Finite Element Analysis

[[Ram Elements - Tension Only Members]]

This page is created with the idea of providing you with the tips and tools that would help you become familiar with the STAAD.Pro CONNECT Edition interface and use it more efficiently. We encourage all users of STAAD.Pro CONNECT Edition software to bookmark this page because we will keep adding content to this page frequently. So stay tuned for exciting updates

[[Customizing the Interface in STAAD.Pro CONNECT Edition]]

[[Tool Search option in the STAAD.Pro CONNECT Edition]]

[[Migrating existing custom Steel section databases to the STAAD.Pro CONNECT Edition]]

[[Handling of Loads in the Physical Modeling interface of STAAD.Pro CONNECT Edition Update 3]]

[[How to adjust the font size for the labels in STAAD.Pro Physical Modeler]]

[[Displaying values of nodal displacements, bending moments etc. on the plots]]

The GUI (graphic user interface) in STAAD.Pro has been redesigned in the CONNECT Edition. Whereas our users are very excited to use the new interface and are actively using it, the rearrangement of the menu has made finding some of the options little difficult for some. Based on their feedback we have made the interface customizable so that users can now easily access the icons that they frequently use and keep these available at all times irrespective of which menu they are in. This wiki outlines quick ways to access certain tools and also lists some easy to use customization options

Option 1 : Customizing the Quick Access Toolbar

There is now a Quick Access Toolbar at the top of the ribbon menu which may be used to add the frequently used icons to the toolbar. Click on the down arrow as shown next

The menu will expand. Click on the More Commands option as seen below

The Customize Quick Access Toolbar dialog box will pop up as shown next which would allow one to select the frequently used tools. Bring those to the right using the green arrows.

Click on OK and all the selected options would now appear on the Quick Access Toolbar at the top as in the next picture

Option 2 : Customizing the Quick Commands Pop up menu

While inside the Whole Structure window press the Spacebar on the keyboard to bring up the Quick Commands menu as shown next. Click on the lower right corner to customize the quick command. 

The following dialog box would popup allowing one to add as many options as needed to the Popup menu

Next time the Spacebar is pressed, all the options would appear as part of the Quick Commands Popup.

Option 3 : Quick access to View icons

Press the SHFT key on the keyboard and right click the mouse to access all the viewing icons as shown next

En el siguiente video le explicamos como personalizar la interfaz en STAAD.Pro Connect edition:

https://youtu.be/hXBybKdus7k

For new users using the STAAD.Pro CONNECT Edition software and for all existing users who are trying to get familiar with the new interface, we introduced a very effective tool search option that would allow you to locate any tool and access it quickly. 

You can simply type in the name of the tool you are looking for in the search box, as seen below, and it would bring up a number of related options. For example let’s say someone is trying to define a plate mat type support using a subgrade modulus. One can go to the search box and type support and all relevant options related to support will pop up

One can then select the option highlighted in the picture above and it would bring up the relevant dialog box as shown below, using which one can define the plate mat type support with an appropriate subgrade modulus value

So the beauty of the tool is, without even knowing how to access to the above dialog box through the new interface, you can simply use the tool search to get to it.

For those of you interested to know the actual location of the tool, you can simply hover the mouse over the option as shown in the next picture and it would show where you need to go, to access the feature.

If you follow the path as displayed in the picture above, you would be able to find the tool within the Interface as explained in the next picture

My company has custom steel section databases and these are mdb files. How can I get these sections into the STAAD.Pro CONNECT edition ?

The section databases in earlier versions of STAAD.Pro were MSAccess databases (mdb files) whereas in STAAD.Pro CONNECT Edition, these have been changed to SQLite databases (db3 files).

Any older mdb file that you may have, can be easily converted to the db3 format following the procedure outlined below

Click on Section Database from within the Specification ribbon menu as shown below

From within Section Database Manager, choose the options marked below and click on the Convert button ( the existing database file is assumed to be aiscsections_ml_SLS )

A command prompt window will show up as seen below showing a message that data has been successfully exported

Click on the "X" to close the command prompt window and note that a "Database converted successfully" message is also displayed at the bottom of dialog box

Click on the "X" to close out of the dialog box and close out of Section Database Manager and out of STAAD.Pro

Now manually copy the aiscsections_ml_SLS.db3 file into the following folder

C:\Program Files\Bentley\Engineering\STAAD.Pro CONNECT Edition\STAAD\Sections

Re-launch STAAD.Pro and you should now be able to access the section database

If you run into issues with accessing your database after following the procedure above, please refer to thiswiki

How can I adjust the font size for the labels ( like node labels, beam labels, load labels etc. ) in the STAAD.Pro Physical Modeler

Have the relevant labels displayed on the screen.

Press the CTRL key on the keyboard and keep it pressed

Roll the wheel of the mouse to dynamically adjust the scale

In older versions of STAAD.Pro (v8i), I was able to show the values of nodal displacements, moments, shears, support reactions etc. on the diagrams itself by going to Results > View Value. How can I do the same in the STAAD.Pro CONNECT Edition ?

After analyzing the model, go to the Postprocessing Mode.

Ensure that the relevant plot is turned on ( for example displaced shape OR bending moment OR shear force etc. )

Choose the Annotate option shown in the picture below

Click on the Annotate button within the dialog box to turn on the values

Recently, Bentley Systems, the global leader dedicated to providing architects, engineers, constructors, and owner-operators with comprehensive architecture and engineering software solutions for sustaining infrastructure, partnered with S-Cube Futuretech Pvt. Ltd. to provide the most comprehensive concrete building design workflow for the Indian market.

This integrated solution is called STAAD.building and it addresses the entire workflow related to the design of reinforced concrete buildings, including conceptual layout and framing, advanced analysis, design and detailing and the production of site-ready drawings along with bill-of-quantity reports. STAAD.building combines the power of STAAD.Pro’s analytical engine with the purpose-built building modelling, design and drawing solutions from S-Cube.

It extends [[STAAD.Pro]], which anchors Bentley's world-leading structural analysis and design software, to accommodate the intricate needs of drawings and design of reinforced concrete structures per Indian standards. The key differentiator is the workflow. Unlike any other software in the Indian market, it helps engineers to conceptualize the engineering model by suggesting preliminary member sizes based on the framing layout, loading conditions, and geographical location. The model is generated in a physical environment to help you generate an analytical model automatically behind the scenes but also offers you the power of STAAD.Pro’s analytical modeling environment to optimize building configurations. It combines the power of a physical modeling system along with an analytical text editor to offer the best possible tools to address every possible need of a building designer.

This is the only solution in the Indian market that completes the workflow by offering an interactive physical member design environment along with complete detailing and drawing generation. Early adopters indicated that drawings are of very high quality and meet the intricate requirements of site-ready drawings. Another recent addition is Bar Bending Schedule (BBS) creation. After detailing structural members, a detailed BBS can be generated in compliance with the Indian detailing standards.

STAAD.building is a bundle package of four products:

• STAAD.Pro is the leading structural analysis and design program (Learn more here )
• STAAD RCDC is the detail reinforced concrete design and detailing program featuring structural components such as beam, column, slab, shear wall etc. and automatically produces drawings and bill of materials
• STAAD Planwin from is a building modeling program that provides physical building modeling environment to create structural frames and components

Also of interest:

[[STAAD Foundation Advanced]] provides the design of common and complex types of foundations along with drawings and step by step hand calculation. STAAD Foundation Advanced may be purchased separately and is a recommended product for end to end building design workflow. (Learn more here)

STAAD Planwin

Some of the features of STAAD Planwin are:

• Seamless integration with STAAD.Pro
• Import architectural centre-line (DXF model)
• Detects beams and columns
• Align / locate members
• Add floor loads and wall loads
• View load distribution element-wise
• Check modelling error at plan level
• Size beams and columns for vertical loads
• Define shear walls
• Generate wind loading
• Generate earth quake loading
• Export 2D and 3D CAD drawings
• Generate accurate 3D analysis model with:
  • Member offsets
  • Releases
  • Beta angles
  • Pier definitions
  • Joint and member loads
  • Wind and EQ load, etc.

With the release of STAAD.Pro CE V22, STAAD Planwin is now included as a feature in STAAD.Pro that is provided as an entitlement with a current subscription program. 

STAAD RCDC

Some of the highlights of STAAD RCDC are:

• General
  • Seamless integration with STAAD.Pro
  • Compliance to latest Indian design standards
  • Auto-detection of design continuum
  • Facility to group members across levels and plan
• Detailing
  • Optimized and practical detailing
  • Interactive detailing interface
  • Control of all detailing parameters
• Drawing: Organized site-ready drawings in DXF format
  • Elevations
  • Cross sections
  • In-plan detailing
  • Layout drawings
  • Text schedules
• Documentation
  • Detailed design calculation report
  • Design summary
  • Failure diagnostics
  • Member properties changed report

For more information on STAAD RCDC, please visit RCDC product page

With STAAD.Pro CE V22, STAAD RCDC is included as a feature with STAAD.Pro Advanced.

This page contains Tech Notes and FAQ's related to STAAD.building ( Building Planner/PlanWin)

1. I cannot access the Building Planner mode, what's wrong?
2. Do I need to install STAAD PlanWin in addition to STAAD.pro?
3. How do I deactivate STAAD Planwin
4. Changing Floor Height in PlanWin Model

This wiki is being created

I have made some customizations to the interface in STAAD.Pro CONNECT Edition. When I install a newer version of STAAD.Pro CONNECT edition, how can I ensure that those customizations are retained ? 

During the installation of a newer version STAAD.Pro CONNECT Edition, the installer keeps a backup of your earlier settings and these are kept within a folder named "Backup_xxxx...". This folder contain those files that have changed due to your customization. You will be notified of this backup folder during the installation itself.

Once the installation finishes, you may copy these files from within the "Backup_xxx..." folder and replace the ones with the same name within the C:\Users\<your_user_name>\AppData\Local\Bentley\Engineering\STAAD.Pro CONNECT Edition\Default folder and that would allow you to retain any customization from the past.

<your_user_name> would be your windows user name. For example for a user named John Smith, it could be John.Smith

Release Date:  Coming Soon

Release Name: Structural Synchronizer CONNECT Edition Update 3 - Patch 1

Release Version: 10.03.01.06

Download Instructions

Structural Synchronizer can be downloaded at the link here, or from Bentley Cloud Services. After signing into the CONNECTION Center, select Software Downloads under My Support. Once on the Software Fulfillment page, the installer can be located by performing a search on “Structural Synchronizer”.

New Features

This release of Structural Synchronizer includes the enhancements described below.

Reduced Installer footprint

Structural Synchronizer now occupies approximately 500 Megabytes less than previous installations.

Bug Fixes

This release of Structural Synchronizer includes the fixes described below.

• Integration fixes with Ram Concept Connect Edition Update 5. Application becomes unresponsive when ISM operation is conducted on Ram Concept 6.5 and Structural Synchronizer 10.3.0.18. Installation of Structural Synchronizer 10.03.01.06 alone resolves this.
• Integration fixes with Ram Elements.  Ram Elements v15 - would report a "Access Denied Error" when performing ISM operation with Structural Synchronizer 10.3.0.18. Resolution requires changes to both Ram Elements and Structural Synchronizer, hence fix involves installation of the latest versions of BOTH Ram Elements (v16) AND Structural Synchronizer (10.03.01.06 and up).

I am doing an analysis with response spectrum loads. I also need to define compression only springs to simulate soil support. How can I do this ?

Response Spectrum loading, due to it's very nature, does not lend itself to any iterative type analysis ( Tension/compression, Pdelta etc.). So the short answer to the question is, response spectrum loading cannot be used in conjunction with compression only springs.

However you may do a couple of things. 

First option is to define the support springs without compression only attribute to analyze the response spectrum cases and other primary cases ( live load, equipment load etc.). Use PERFORM ANALYSIS and CHANGE after that. Subsequently re-define the support springs with compression only attribute followed by REPEAT LOADs to combine the primary cases. For combining the response spectrum cases with other loads, you still have to use LOAD COMBINATION. Once all REPEAT LOADs and LOAD COMBINATIONs ( for response spectrum combos only ) are defined, follow it up with another PERFORM ANALYSIS and CHANGE. 

Other option is to use equivalent static seismic loads to represent seismic loads as opposed to using a response spectrum load in which case you would be able to use REPEAT LOADs and compression only springs to combine gravity+seismic loads. You may scale the equivalent static seismic loads by the ratio of the base shears ( equivalent static base shear/ response spectrum base shear).       

1. Should I specify Response Spectrum in ALL directions in the same load case
2. In base shear what is considered as the base
3. I added dead+live load as seismic mass. Do I need need to define these loads separately too ?
4. When Specifying Damping, the Displacements and Forces Remain Same
5. How Does Ground Acceleration Scale Factor Work
6. How to Input the Missing Mass Correction Command
7. Rayleigh Method Calculate Natural Frequency
8. The natural frequencies obtained during a Response Spectrum Analysis do not match the values calculated using the CALCULATE RAYLEIGH FREQUENCY command
9. Spectrum Load Case Joint Failing?
10. Base Shear Does Not Match the Summation of Shears
11. No Unsupported Masses Entered Error
12. Is Design Ground Acceleration Correct
13. Is it possible to save the floor spectrum data that is calculated by STAAD.Pro in a text or .xlsx file ?
14. Missing mass – How to Consider
15. Colombian Seismic Verification Example
16. Multiple Floor Spectrum Generation Block Not Allowed
17. [[Response spectrum analysis with compression only springs]]

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!

How can I model a shear plate connection with two columns of bolts?

1. Open the Connection Pad by clicking on Edit - Connections toolbar - Shear Connection (see screen capture) or double-clicking on the large display of the model connection.

2.  In the Connection Pad, change the "Bolt Eccentricity Calculation Method" to "Manual."

3.  After changing the bolt eccentricity option, a line for number of bolt columns will appear with the Single Plate information:

3. Enter the desired gage between the columns of bolts

4.  Define the appropriate eccentricity to use using the parameter "eb: Load eccentricity to bolt group" also found with the Single Plate information.

See Also

RAM Connection Capabilities and Modeling FAQ

Why are beam graphs not displayed for response spectrum load cases in STAAD.Pro ?

For a response spectrum load case, the responses that you get at the member start/end and also at intermediate section locations, are all individual maximums. In other words these values do not occur simultaneously at the different sections along the member length and so it is not correct to plot a graph with those values. In addition, when modal responses are combined to generate the final output for a response spectrum load case, the signs are lost and so plotting a graph with such numbers is of little value.