The Vertical force derived from Response spectrum Analysis & Equivalent static Method of Seismic Analysis does not match

Dear Sir,

For Load Case 4, used in both staad model (attached herewith) with all the parameters same but different method of Seismic Analysis shows different value of vertical forces.

Dynamic Method.STDStatic Method.STD

(Please use Importance factor I =1.75 if the value get automatically erased from seismic parameter.)

  • Not sure if I understood the question correctly but is the expectation that LC 4 should yield identical results for Static Method.STD & Dynamic Method.STD? Not really as the method deployed in two models are completely different. The component load case for LC 4 i.e. LC 1 is a static load case (considers only fundamental mode, time period supplied as user input PX = 0.121 sec) in Static Method.STD and for Dynamic Method.STD LC 1 is a response spectrum load case (considers 6 modes in this file with associated time periods based on eigen solution). So the two models are completely different and difference in results are expected.