Numerical investigation into the performance of cold-formed steel framed shear walls with openings under in-plane lateral loads

Recently, there has been a resurgence in the adoption of lightweight cold-formed steel (CFS) profiles as structural elements in low- to mid-rise modular construction. Typically, openings for doors and windows are ever-present in the front and rear elevations where shear walls find their optimal position to ensure lateral stability in CFS modular structures. These architectural design features translate into reduced areas for lateral load resistance throughout the structure. This paper discusses the performance of CFS framed shear walls with openings under lateral loads through experimental tests and numerical simulations. Overall, three shear wall typologies were designed for force transfer around opening (FTAO) and tested under monotonic lateral loads (nine tests in total). An advanced finite element analysis (FEA) modelling protocol was elaborated to simulate the lateral behaviour of the tested walls as well as to interpret the physical tests. Evaluation of the numerical and experimental test results validated the FEA modelling protocol that demonstrated to be reliable in predicting the strength and stiffness as well as failure modes of CFS framed shear walls with openings subjected to lateral loads. The effects of sheathing-to-CFS screw spacing, the size and number of openings as well as the geometry of sheathing panels on the lateral behaviour of CFS framed shear walls were scrutinized. Subsequently, load-path mappings from the developed modelling protocol enabled the analysis of the flow of the in-plane lateral loads from the sheathing-to-CFS screw level into the wall system level where insight into a more efficient lateral design of CFS framed shear walls with openings have been highlighted. The obtained results shed light on the conservative nature of the AISI S400-15 design provisions for Type II shear walls and that of the perforated design methods available in the literature.