MODELLING IN-PLANE AND OUT-OF-PLANE RESPONSE OF INFILLED FRAMES THROUGH A FIBER MACRO-MODEL

A new fiber macro-model for the simulation of combined in-plane and out-of plane response of infilled frames subjected to seismic actions is presented in the paper. The model consists of 4 pinned struts (two diagonals, one horizontal and one vertical) modeled with the nonlinear beam/column fiber-section elements available in OpenSees. The model is particularly suitable to predict the out-of-plane response as fiber-section elements can account for the coupling between axial load and bending moment occurring because of the arching mechanism developed by the infills beyond the first cracking. Moreover the model can account for the effect of the reciprocal damaging accumulated both in-plane and out-of-plane during shakings. The procedure for the identification of the struts is presented in the paper and is validated with experimental test data from different authors. The proposed model may be used as a computationally-light and effective tool for the assessment of the response of 3D structures subjected to ground motions acting in arbitrary directions