Innovative System for Earthquake Resistant Masonry Infill Walls

Abstract

Severe damages of masonry infill walls in reinforced concrete and steel frames have been observed after many earthquakes. Typically, masonry infill walls are loaded not just in-plane and out-of-plane but also simultaneously in both directions. While the damage due to the in-plane loading is caused by the increase of interstory drift, out-of-plane collapse is induced by high inertia forces perpendicular to the wall. In reality, both effects strongly interact with each other leading to a further reduction of deformation and strength capacity of the masonry infill. Within the project INSYSME the authors proposed the new system INODIS which decouples the frame and the masonry infill by means of specially shaped rubbers placed in between frame and infill. The decoupling reduces the damages and the infill behaves like a real non-structural element. At the same time the special shape of rubber connection prevent an out-of-plane failure of the infill wall. A series of full scale tests on RC frames with clay brick masonry infills have been carried out in order to validate the efficiency of the system. The experimental tests were carried out separately for in-plane and out-of-plane loading as well as simultaneously applied loads in both directions using a special experimental set-up with airbags. Furthermore small specimen tests were carried out to check material characteristics of the components and the resistances of the connections. The experimental results are used as a basis for the validation of the numerical models, developed on micro and macro level. These models can be used for parametric studies to derive simple design rules for everyday practice.