Design criteria and seismic performance of moment frames with parabolic slit shear walls

This research investigates the seismic characteristics of steel moment frames, when parabolic shape slit shear wall is added as infill to the frame. For this purposes, the stiffness, strength, energy dissipation and ductility capacity of the proposed combined system, which work in parallel, are studied. The proposed system is considered as a new seismic force resisting system. The force distribution mechanism in the slit web and boundary elements subjected to lateral force are investigated. The design criteria and equations required for design use are developed. Results of the experiments on a steel moment frame specimen and two frame specimens with slit shear plates, as well as finite element analysis of the specimens are used to validate the results of analytical equations. Desirable performance of proposed system is also verified by nonlinear static and time-history analyses of a four story structure. The results show that the proposed slit shear walls, in addition to increasing the stiffness, strength, ductility, and energy dissipation capacity, reduce the inter-story drift ratios and also actions on the boundary elements of moment frames, when subjected to strong ground motions, and prevent damage to other structural elements by absorbing the plastic deformations.