TESTS ON SPECIAL ANCHORS FOR MASONRY INFILLS WITH SPECIAL OPPORTUNITY FOR SEISMIC RETROFITTING

Reinforced concrete frame structures are treated as moment resisting frames, with different design options. The bearing capacity of such frames can be significantly increased by masonry infill walls that act as shear walls. The greatest supporting effect of the wall on the frame is expected in in-plane (IP) direction. The IP loads are introduced into the wall as compressive forces, whereas the Out-of-plane (OoP) loads generate shear forces at the joints between the frame and infill. IP loads can be transferred very well through mortared joints, while additional securing is recommended for OoP direction. Particularly in case of earthquakes, infills must withstand OoP loads to prevent failure, which can endanger people and block escape routes and to assure they are still suitable for further actions especially for later upcoming loads in IP direction. A good opportunity to improve the OoP performance is to place special ties in the joints between the frame and infill. The action on these ties can be determined from the load carrying capacity and deformation behaviour of the frame structure or by calculation according to EN 1998 or similar. As the intended anchors are to connect a concrete element to a masonry wall, a system is proposed that consists of an anchor channel cast in concrete into which special masonry anchors engage. This system has the advantage that it is easy to install and can be reinstalled very simply in the event of renovation or damage. This fastening system can also be post-installed in the event of seismic retrofitting. These fixings have a decisive influence on the interaction between the RC frame and the infill and require a proper design, best to be achieved by tests in different scales. In this paper, the technical background is explained, and the various experimental results are illustrated and compared.