### A Dynamic Finite Element Code for Analyzing Collapse Behaviors of Framed Structures under Seismic Loads

Abstract

A new dynamic finite element code to simulate collapse behaviors of structures
under excitation at fixed points is developed using the ASI-Gauss technique.
The technique is a modified version of the formerly developed Adaptively
Shifted Integration (ASI) technique for the linear Timoshenko beam element,
which computes highly accurate elasto-plastic solutions even with the minimum
number of elements per member. The ASI-Gauss technique gains still higher
accuracy especially in elastic range, by placing the numerical integration
points of the two consecutive elements forming an elastically deformed
member in such a way that stresses and strains are evaluated at the Gaussian
integration points of the two-element member. Moreover, the technique can
be used to express member fracture, by shifting the numerical integration
point to an appropriate position and by releasing the resultant forces
in the element simultaneously. The numerical code can be used to analyze
dynamic behaviors of framed structures, initiating from elastic range to
a total collapse. Simple numerical tests are conducted to verify the proposed
code. Moreover, a seismic collapse analysis considering member fracture
and contact is performed on a large-scale framed structure, and practical
results are obtained in a reasonable short calculation time.

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