I was wondering if it is possible to force a group of members to have the same size. When I use SELECT with a group, I get different sizes for different members in the group, depending of course on forces on particular members. I would like to force a group of members to all be designed with the largest member inside the group.
For example I would like to maintain physical member symmetry in an asymmetrically loaded truss.
This has got to be possible, but I can't find it described anywhere. Can someone point me in the right direction?
Thanks!
Hi,
You can use the SELECT command followed by the GROUP command to do the same. For example, the format should be like:
SELECT ALL
The above command instructs the program to select the most economic section for all the members based on the results of the analysis.
GROUP MEMB 1 3 4
GROUP MEMB 5 6 7
Although the program selects the most economical section for all members, it is not always practical to use many different sizes in one structure. Grouping is a procedure by which the cross section which has the largest value for the specified attribute, which in this case is the default attribute of section area, from among the associated member list, is assigned to all members in the list. Hence, the cross sections for members 1, 3 and 4 are replaced with the one with the largest area from among the three.
PERFORM ANALYSIS
As a result of the selection and grouping, the member sizes are no longer the same as the ones used in the original analysis. Hence, it is necessary to reanalyze the structure using the new properties to get new values of forces in the members.
You can go through attached example problem 1 for more details.
Answer Verified By: PvB
EXAMP01.STD