Seismic behavior of semi-supported steel shear walls

During the recent past decade semi-supported steel shear walls (SSSW) have been introduced as an alternative to the traditional type of steel plate shear walls. In this system the shear wall does not connect directly to the main columns of the building frame; instead it is connected to a pair of secondary columns that do not carry vertical gravity loads. In this paper, the interaction between the wall plate and the surrounding frame is investigated experimentally for typical SSSW systems in which the wall-frame has a bending-dominant behavior. Based on the possible storey failure mechanisms a simple method is proposed for design of the floor beams. A quasi static cyclic experimental study has been performed in order to investigate the collapse behavior of the wall-plate and surrounding frame. Furthermore the test setup has been developed in order to facilitate standardized cyclic tests corresponding to those described by ECCS. From this investigation hysteresis loops are obtained and it is seen that pinching occurs in the loops, since the plate system is un-stiffened. The results of the experimental study are compared to the results obtained using the proposed analytical method. As predicted the study shows that the frame has the capability of developing a tension field in the wall plate, so that the wall plate yields before the frame.