Lateral Behavior of Traditional Chinese Timber-Frames Strengthened with Shape-Memory Alloy: Experiments and Analytical Model

This study presents the test results of three specimens of traditional Chinese timber frames (TCTFs) with two types of column heights and two types of vertical loads. The specimens were initially loaded to damage, then strengthened with different numbers of shape memory alloy (SMA) wires and retested. The lateral performance, such as failure modes, envelop curves, stiffness degradation, and energy consumption, was analyzed to evaluate the SMA strengthening effects. Results showed that the lateral bearing capacity, stiffness, and energy consumption of the strengthened specimens were evidently improved, and even exceeded the undamaged level when relatively larger displacements were imposed. An analytical model for frames jointed by semirigid mortise–tenon and hinged column-foot joints (SHFs) was proposed. Lateral load-displacement responses of both the strengthened and unstrengthened specimens were predicted by the model, and good consistency was obtained compared with the test results. The influence of column heights, vertical loads, strengthening degree, and frame spans on lateral behavior of TCTFs also were evaluated through both experiments and parametric studies. This work provides a valuable reference for the restoration of historic timber structures.