Experimental testing of spliced glulam joints for large-span timber structures

In recent years, wood has become an increasingly popular building material for its environmental friendliness. Large-span timber structures are in high demand, of which the spliced joints play an important role for the main structural members. In this research, six specimens with two connection configurations, i.e., the slotted-in-steelplate connection (SC) and the cover-plate connection (CC), were designed and subjected to cyclic loading tests. Besides the traditional data acquisition system, contact-free displacement measurement was also applied. The feasibility was verified since the moment-rotation curves obtained through the two methods showed strong consistency. Through the analysis of the mechanical properties of the joints, different methods for the determination of the yielding point of the specimens were compared and discussed. The test results show that the ultimate strength and stiffness of the CC connection were 59.04% and 187.7% higher than that of the SC connection, whereas the ductility of the former was 77.02% lower than that of the latter. Factors influencing on their mechanical properties were further analyzed. It is noted that while the ultimate strength is dominated by the steel plates, the stiffness and ductility depend more on the glulam elements and fasteners. Recommendations were also proposed as a design basis for the two types of connections.