Rotational Behaviors of Fork-Column Dou-Gong: Experimental Tests and Hysteresis Model

This paper presents an investigation on the rotational behaviors of fork-column Dou-Gong. Five scaled specimens in different construction forms were manufactured and tested by low reversed cyclic loading under three different vertical loads. The failure modes, envelope curve, strength degradation, deformability ratio, stiffness degeneration, and energy dissipation were assessed and compared. The results indicated that the increment of the rotational stiffness gradually decreases with increased vertical load. The relationship between rotational stiffness and vertical load can be simplicity expressed by a logarithmic function. The length, construction form, and number of linking beams are the main parameters affecting the rotational behaviors of single Dou-Gong. Reducing the length or enhancing the combined effect of the linking beams can effectively improve the bearing capacity and deformation capacity of the Dou-Gong, as well as energy dissipation capacity. The rotational behaviors of single Dou-Gong with one linking beam are worse than those of Dou-Gong linked by two beams. In addition, the double Dou-Gong exhibits better symmetry and plumper area than the single Dou-Gong, thus resulting in 109%, 78%, and 163% increment in bearing capacity, rotational stiffness, and energy dissipation, respectively. The moment-rotation curve of fork-column Dou-Gong is nearly trilinear and based on the appropriate mechanical parameters from the test results, the nonlinear hysteresis characteristics of the fork-column Dou-Gong can be simulated by an improved double-target model.