Experimental and numerical research on the lateral behaviour of glued timber frame structures with and without X-type diagonal bracing

Abstract

The advanced processing technology of glued wood can provide strong support for the construction and application of the modern timber structures. The modern timber structure can meet the requirements of low-carbon development goals and natural living standards, but there still exist some technical difficulties to research, such as seismic performance and design code problems. Hence, this paper presents the lateral behaviour of glued timber frame structures with and without X-type diagonal bracing by experimental and numerical research methods based on these problems. Two single-layer single-span bare glued-laminated timber (GLT) frame specimens and two GLT frames infilled with X-type diagonal bracing specimens with a 1:1.5 scale were designed to investigate the lateral behaviours under the cyclic loading tests. Three types of beam-column joint connectors (the exposed type with infilled steel plate, the coated type with infilled steel plate and the extended coated type with infilled steel plate) were designed to guarantee the effective connection between components. The failure mode, hysteretic characteristics, lateral load-bearing capacity, stiffness degradation, deformation and the lateral load resistance cooperative working mechanism between X-type diagonal bracing and GLT frame of specimens were analyzed. The test results present that the lateral behaviour of the GLT frame is significantly improved after being infilled with the X-shaped diagonal bracing, and the yield lateral load-bearing capacity and the elastic stiffness of the coated type beam-column joint connection in the GLT frame were 1.876 and 1.36 times than that of the specimen with exposed type beam-column joint connection, respectively. The beam-column joint of the bare GLT frame specimen is failure before the column-base joint. The diagonal bracing joints of the GLT frame specimen infilled with the X-shaped bracing were failures first, and then the beam-column and the column-base joints of the GLT frame were damaged. For the specimen infilled with the X-type diagonal bracing, the lateral resistance load was borne by the GLT frame and diagonal bracing, in which the percentage of the lateral load borne by the diagonal brace gradually decreases, while the percentage of the lateral load borne by the GLT frame gradually increases. In addition, the load-deformation relationships of the specimen joints were derived. Based on these relationships, the numerical analysis of the specimen was carried out to study the influences of GLT frame span-depth ratio, the slenderness ratio of GLT diagonal bracing and the wall thickness of steel tube diagonal bracing on the lateral resistance of this structural system.