Seismic assessment of RC frames infilled with innovative CFS walls considering seismic orientation effect

The metal tailings porous concrete cold-formed steel (MCFS) wall is an innovative cold-formed steel (CFS) wall with good thermal and mechanical properties, which has the potential to be widely utilized as the infilled wall (IW). In this paper, the MCFS walls are adopted in the reinforced concrete (RC) frame, and the seismic performance of the building subjected to ground motions with various incidence angles are investigated. Three-dimensional finite element model of the studied building is developed with full consideration of the in-plain (IP) and out-of-plane (OP) behavior of MCFS walls. Incremental dynamic analysis is conducted to obtain the deformation responses of frames and damage ratios of MCFS walls under the combined effect of seismic intensity and orientation. Fragility curves are generated to assess the seismic performance of the building and investigate the effect of ground motion orientation. The results validate the superior performance of infilled MCFS walls, and reveal that the seismic orientation has a considerable impact on the response along each reference axis of the structure. Furthermore, different incidence angles induce up to 10.2% and 14.4% variations in the median S-a(T-1) of fragilities for the frames in X and Y axes, and the corresponding change rates in the median S-a(T-1) for the walls are 13.5% and 15.1%, respectively. However, for the overall performance of the building, the seismic orientation effect is less significant. The rates of changes in median S-a(T-1) are less than 4% for both frames and MCFS walls.