Hi, I model a steel moment resisting frame considering concentrated plasticity hinge model based on Modified Ibarra Krawinkler Model. Steel moment resisting frame is modeled with elastic beam-column elements connected by zeroLength elements which serve as rotational springs to represent the structure’s nonlinear behavior. The springs follow a bilinear hysteretic response based on the Modified Ibarra Krawinkler Deterioration Model.
My question is if I do not consider constrain in beam-column joints in a floor to have the same lateral displacement using the "equalDOF" command, my time period is 0.48 which is my desired time period. However, if I consider constrain in beam-column joints in a floor to have the same lateral displacement using the "equalDOF" command, my time period reduced to 0.37. I need my time period should be 0.48. Please give me suggestion, how can I set my time period 0.48 considering constrain.
constrain problem
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selimgunay
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Re: constrain problem
Is this a 2D or 3D frame. If it is 2D, because the axial stiffness of the beams is generally large enough, it is a bit questionable why your period changes from 0.48 sec to 0.37 sec when you include an "equaldof" command. If it is a 2D frame you don't need the equaldof command to start with.
Re: constrain problem
Thank you very much for your cooperation. It is working without considering equaldof command and time period is 0.48 sec.