Finite Element Motion Analysis of Furniture under Seismic Excitation


In big earthquakes, improperly secured furniture could move violently and may give high risks of human injuries, even when the building itself has small damages. Many tumbled furniture such as chairs and desks in schools could become fatal obstacles that obstruct children from evacuating. Therefore, it is important to know the overturning behaviors of furniture under seismic excitations, as well as the behaviors and damages of the building itself. The objective of this research is to develop a finite element code to analyze motion behaviors of furniture under seismic excitations. To realize various contact phenomena during seismic excitations, the ASI (Adaptively Shifted Integration)-Gauss code including frictional contact algorithm based on the sophisticated penalty method was adopted. This code was originally developed to analyze collapse behaviors of buildings with phenomena such as fracture and contact. First, some shake-table tests of a chair and a desk used in schools were performed. After validating numerical results with the experimental results, we carried out an analysis of a model with chairs and desks arranged in a classroom. Earthquake countermeasures depending on a difference in the coefficients of dynamic friction are then discussed according to the numerical results. Secondly, we simulated the motions of furniture arranged in an upper floor of a medium-rise reinforced concrete building. Two types of furniture on the upper floors of the building with different constraint conditions were assumed. We simulated the differences in the behaviors of the furniture with and without earthquake countermeasures.