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Optimization of connection between traditional Japanese post and beam frames and Midply infills Liang, Zhen


This thesis studied an optimized application of screw connections for a novel Japanese post and beam (J-P&B) shear wall system using Midply elements as infills. The connection is a single shear timber-to-timber screw connection between the frame's posts/beams and Midply's studs/chords. The research aimed to design an efficient connection composed of stronger but fewer fasteners based on theoretical and experimental studies. The connection's theoretical analysis was conducted first using EN1995, O86, and Tomasi methods, which revealed the remarkable contribution of the connection's axial resistance to the overall performance. High connection load-carrying capacities were obtained using inclined installed screws with appropriately arranged threads in both wood members. The analytical results were verified by 12 types of connection tests under monotonic load and 3 types of connection tests under reversed-cyclic load. Eventually, connection type 'CYL260-45V-18H' was selected as the candidate for use in the optimized system. A finite element (FE) model MPBWALL was developed to simulate the push-over response of the shear wall system, using the commercial software package SAP2000. Because of the particular layout of Midply, the sheathing's deformation is confined by studs/cords on both sides. The consequent 'stiffening' effect was considered in the model. Results of MPBWALL suggested two optimized wall configurations, MPB-01 and MPB-02, using CYL260-45V-18H as the connection. A total of 4 full-size shear walls were tested both under monotonic and reversed-cyclic load. Compared to conventional solutions, the optimized system yielded a higher wall multiplier of 5.52 (evaluation index of Japanese shear wall) using 38% fewer fasteners. In addition, the relative slip between the frame and infill was significantly reduced.

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