Experimental and theoretical study on seismic behavior of Dou-Gong brackets on column under the load in overhanging and width directions

The distinctive structural construction in the overhanging and width directions of Dou-Gong (DG) bracket in ancient timber buildings results in different seismic performances of the DG. To study the effect of loading direction on the seismic behaviors of the DG bracket, the pseudo-static tests are conducted on two Dou-Gong brackets on column in the overhanging direction (DG-1) and width direction (DG-2), respectively. The failure mode, hysteretic behavior, skeleton curve, stiffness degradation, and energy dissipation capacity of the DG are obtained. Besides, the rotational, sliding, and bulging displacements as well as their proportions of DG component's horizontal displacement are analyzed. In addition, a theoretical model was proposed to calculate the horizontal load of the DG. Results show that the failure modes of DG-1 and DG-2 are rotation and relative slip of DG components, broken of Xiao 1, and embedment of Flat-Beam. DG-1 has a superior bearing capacity, initial stiffness, and energy dissipation capacity compared with DG-2. However, both DGs exhibit good deformation ability and obvious stiffness degradation. The horizontal displacement component of DG-1 increases first and then tends to be stable with the loading displacement, while the component displacement of DG-2 increases gradually. The rotational and sliding displacements of the DG components are significantly larger than the bulging displacement. The higher the DG components, the larger the rotational displacement. The proportion of the component's sliding displacement is larger than the rotational displacement for DG-1, while the proportion for DG-2 is opposite. The theoretical model for the horizontal load can effectively calculate the bearing capacity of DG brackets.