Abstract

Recently completed research on C-shaped post-tensioned (PT) timber core-walls, using the Pres-Lam system, has demonstrated their lateral load resisting capability and provided data for the calibration of numerical models. Additionally, coupled CLT shear walls with steel link beams have been cyclically tested and exhibited a ductile failure mode through yielding of its link beams between adjacent CLT wall piers. This study first provides a summary of the two high-capacity mass timber wall systems, then proposes their combination as a PT core-wall assembly for applications around elevator shafts or stair cores to resist earthquake loading. The proposed system uses two C-shaped core-walls which are coupled in their weak-axis by a series of steel link beams over the system's height. A 6-storey sample building was designed following the equivalent static force procedure according to the National Building Code of Canada 2015 with assumed factors of Rd = 3.0 and Ro = 1.5. A nonlinear model of the system was created and calibrated based on the results of system-level experiments on C-shaped PT and beam-coupled walls. Nonlinear pushover analyses were completed in each orthogonal direction of the system and its seismic performance was assessed using the capacity demand diagram method. Based on this assessment method, global drifts of 0.67% and 1.0% were predicted for a ULS earthquake event in the C-shaped and beam-coupled wall directions, respectively. Although limited, the results of this study indicate the proposed core-wall system concept is feasible and with further study (such as nonlinear time history analyses and evaluation of increased building heights) may be a viable LLRS for mid-rise mass timber buildings in seismically active regions.