On a recent project, I encountered a new term: the zero period acceleration, or ZPA. Of course it's a common term, just new to me. The ZPA is the peak pseudo-acceleration for modes of vibration whose frequency is very high relative to the input excitation. These modes respond in-phase, or quasi-statically, with the input excitation, … Continue reading All About Making that ZPA
Tag: Modal analysis
Modal Participation Factors
Computing modal participation factors (yes, I know it's a misnomer) from an OpenSees model is straightforward if you define only nodal mass with no element mass. Examples are available online showing how to compute the factors in OpenSees using Tcl, but let's go over how to do it with OpenSeesPy. After you define your model … Continue reading Modal Participation Factors
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