Experimental and Numerical investigations of Reinforced Concrete Frames with Masonry infills under combined in- and out-of-plane seismic loading

Abstract

It is well known that seismically loaded reinforced concrete frames with masonry infills exhibit an unfavourable behaviour which can lead to serious damages of the masonry infill panels and the surrounding reinforced concrete frame. Especially recent earthquakes clearly showed the low seismic resistance with serious consequences for the occupants of affected buildings. This is astonishing at first glance, since numerous experimental investigations and numerical simulations have been carried out to study the seismic behaviour of reinforced concrete frames with masonry infills. The results of the fundamental research served as a basis for the derivation of simplified seismic design approaches, which consider the seismic actions in-plane and out-of-plane as a separate design problem. Although the necessity of considering the interaction has already been pointed out by some authors, there is no applicable design concept for the engineering practise available. Within the framework of the joint European project INSYSME, comprehensive experimental test campaigns were carried out on reinforced concrete frames with masonry infills. The tests include separate in- and out-of-plane loading, sequential in- and out-of-plane loading and simultaneous in- and out-of-plane loading conditions. The experimental results lead to significantly lower resistances for sequentially applied loading and to rigorous reductions of the seismic resistance if the loads are applied simultaneously. The results show clearly, that the existing design concepts are insufficient and definitely not on the safe side. This article presents and discusses the main findings of the tests results and further simulation results.