I recently tried the feature of generating the properties of a built-up section by using the "Tools / Create user table / Add new property" then checking the "Define Profile Polygon" and inputting the perimeter points. I was able to generate the cross-section and the properties, but when I look at the member in the model while rendering "Full Sections" or "Sections Outline", the member is shown offsetted from the local X axis defined by the Start and End joints. I was expecting to see the local X axis going through the CG of the cross section - Is there a way to make this happen?
I'm listing below the input of a simple model where the problem can be observed.
STAAD SPACEUNIT FEET KIPJOINT COORDINATES1 0 0 02 50 0 0MEMBER INCIDENCES1 1 2 START USER TABLETABLE 1GENERALTESTMEMB1.25 1.5 0 1 0 0.175694 0.09375 0.217853 0.202724 0.1875 1.00894 1.06914 -0.401111 0.291667 0.000966092 1.5PROFILE_POINTS -0.5 -0.633333 0.5 -0.633333 0.5 0.366667 0 0.866667 -0.5 0.366667ENDMEMBER PROPERTY1 UPTABLE 1 TESTMEMBSUPPORTS1 PINNEDFINISH
I find the same problem (it still persists in version 20.07.06.35). Although the member centreline is in the correct place in the model and the analysis results appear correct, the rendered depiction of the section is positioned wrongly. The actual cross-section is in itself drawn correctly - but it has one corner of the section positioned on the centreline of the member.
When entering the section coordinates I have also found in the past that if a point other than the centroid is used as the local cross-section origin then when the input table is re-opened to check or amend the values then StaadPro will have changed the coordinates to set the local origin to the section centroid. That's not necessarily a problem but the help file should mention that. (I haven't tried to replicate that recently so it might have been fixed already.)
Perhaps the two effects are related ?
Hi Tibi: It is an anomaly in pictorial representation and does not have any bearings on the analysis results.
Hi Alistair: You are correct about the redifining of the profile co-ordinates based on making cg the origin. I will make it a point to inform to include the same in the help documents.
Sudip Narayan Choudhury
hi.. i want to generate a moment curvature diagram for a beam member at a particular location. Can i do it using Stadd pro. If yes then how??
Do you mean the bending moment diagram? You need to go into the post-processing mode and click on the "Mz" and "My" switches as appropriate, to activate the corresponding diagram. This is shown in the attached screen shot. The "Mz" diagram will be activated by default, if you go into the Post-processing > Beam page.
Thanks, that's helpful to clarify StaadPro's behaviour with user-defined section coordinates.
However, the point about the graphical misrepresentation of such sections has not been addressed. 3-D rendered images of structures are very useful for visual checking of the structural configuration and also for presentation of images of the structure to the client, checking authorities and fabricators.
Above is an example of the mis-representation of a user-defined section. The circled beam is a triple-web beam which is in fact aligned with the dummy post members below it and the truss node above it. Doesn't look like it though.... the top right corner of the top flange is shown at the location of the centroid of the member.
I checked that the beam is in fact correct by temporarily substituting a standard UB section; all showed correctly with that.
If the visual image is wrong that does not engender confidence in the correctness of the program or its results. You and I may well know that the centroid of the beam is in the correct place and that the analysed results are absolutely correct. However all that 3rd parties see is a beam in the wrong place. That doesn't help the image of either StaadPro or of my skill as an engineer.
I can't imagine it is overly difficult to correct the graphical presentation of a built-up section - please arrange for that to be done for a future StaadPro release.
i am recently working on the nonlinear behavior of structures. so i need to locate the plastic hinge formation and the subsequent behavior after that. i also need to generate a graph (moment vs curvature)and find the load at which it leads to the rupture of the beam. and how am i supposed to do it in staad..