Upper-lower staggered composite wood beam systems are widely preferred by architects for long-span glulam roof structures. However, the mechanical characteristics of its connections remain unclear. Using the large-span roof structure of the Yixing Art Museum as the engineering background, an innovative joint configuration is proposed, in which a cross-shaped steel plate in conjunction with self-tapping screws connects the upper and lower staggered composite timber beams. Shear performance tests were conducted on composite beam joints. The test results show that using cross-shaped steel plates and self-tapping screws at the composite beam, joint interfaces can effectively enhance the shear capacity between interfaces. The load-displacement behavior of the test joints presents three distinct stages: elastic stage, nonlinear stage, and yield stage. The average ultimate shear capacity and initial stiffness of the specimens were 218.5 kN and 35.4 kN/mm, respectively. The typical failure modes included screw yielding and local crushing of wood fibers around the screws, indicating a ductile failure mode. Furthermore, the Foschi model effectively predicts the mechanical behavior of the proposed composite beam joints.
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