Seismic Load Generation on Disjointed Structures

Question

Hello, 
 
 I would just like to clarify if the issue stated in this help forum is updated. 
 Analyzing multiple disjointed structures in one model 
 Has this issue been addressed in STAAD Connect Edition? If yes, which update version has it. If not, are there plans of fixing it? 
 Thank you.

Abhisek M · Accepted Answer

Hello, 
 This is not a bug but the way the software works. As for seismic design only one mass matrix is formed, disjointed structures does not provide accurate results. If the structure is disjointed it is recommended to create separate files.

Aswathi A · Answer

The reason why having disjointed structures in seismic analysis is not recommended is the following. 
 In the Equivalent lateral force method, the lever arm for torsional moment is to be calculated from the dimension of the building along the direction perpendicular to the direction of the earthquake. To achieve this in a model with multiple structures, the program would have to calculate the dimension for the individual structures and apply the one appropriate to each structure. Currently, all the individual structures use the same value which is the largest dimension from among all the structures in the STAAD file. 
 The dynamic participation factors should be calculated based on the masses of the individual structures. Currently, it is based on the total mass of all the structures in the STAAD model.

DSANJU · Answer

Please note that stiffness of the disjointed structures will be considered separately but the problem is that there will be a single mass matrix. In other terms the total seismic weight of the multiple structure will be conceded to compute a single horizontal base shear that will be distributed as storey shear.

Seismic Load Generation on Disjointed Structures

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