Seismic performance of wooden straight-tenon joints reinforced with lightweight steel members

Abstract

A large stress is produced in the straight-tenon joints of a wooden structure during an earthquake, and this can cause the tenon to pull out and destabilize the timber frame. Therefore, four types of lightweight steel reinforcements for straight-tenon joints are herein proposed. Seven straight-tenon douglas fir joint specimens include one unreinforced and six reinforced specimens, are subject to low-frequency cyclic loading according to the Chinese specification JGJ/T101-2015. Failure modes, moment-rotation hysteretic curves, skeleton curves, stiffness degradation, strength degradation, energy dissipation capacity, and tenon pulled-out values are obtained and discussed. The results indicate that the unreinforced specimens are damaged because of the large tenon pulled-out values and obvious pinching effect of the hysteretic curve. Compared with unreinforced specimens, the final failure modes of all reinforced specimens are changed, hysteretic curves become fuller, peak load increases by more than 10%, initial stiffness increases by more than 25%, and bearing capacity degradation improves significantly; they achieve a good reinforcement effect. The strength and energy dissipation of the specimens increased with an increasing triangular-rib size. An FE model is established, and the FE-predicted results match the test results well. The parametric study results indicate that increasing the size of the tenon and the length of the tapping screw can effectively improve the seismic performance of the specimen.