Investigation on seismic performance of inclined Dou-Gong bracket between columns of ancient timber structures

To investigate the seismic behavior of the inclined Dou-Gong (DG) brackets, three full-scaled Dou-Gong bracket between columns with different inclinations along the width direction were tested under the pseudo-static test. The failure mode, hysteretic characteristic, stiffness degradation, deformation and energy dissipation capacity as well as the deformation modes of DG were discussed. Besides, numerical analysis of DG's stress distribution and seismic behavior of DG brackets inclined in the overhanging direction was also studied. Parameter analysis was conducted to study the effect of frictional coefficient, vertical load and wood properties on the bearing capacity of DG. The results demonstrated that the DG bracket rotates as a whole and the relative slip of Da-Dou and Pingban-Fang leads to the shear damage of Mantou-tenon when DG failed. As the inclination in width and overhanging direction increases, the positive bearing capacity and lateral stiffness decrease, while the negative direction increases. The DG's negative deformation ability is better than the positive direction and the larger the inclination, the stronger the deformation capacity. However, inclination reduces the energy dissipation capacity of DG. Rotation deformation is the main deformation mode of the DG bracket. Increasing the frictional coefficient, vertical load and compressive strength along the grain improves the bearing capacity of the DG, but the bearing capacity is slightly affected by the elastic modules along the grain. The research results can provide a scientific basis for the performance evaluation and repair protection of inclined DG brackets.