NUMERICAL SIMULATION OF STEEL BRACE HYSTERETIC BEHAVIOR BASED ON THE FORCE ANALOGY METHOD

Material nonlinearity and geometric nonlinearity for steel braces subjected to applied loads occur frequently and the numerical simulation of complex nonlinear force-deformation relationship becomes increasingly important and significant. In this study, a model of nonlinear hysteretic behavior for steel braces was presented based on the force analogy method, which used a plastic hinge and a slide hinge to simulate the behavior of plastic bending deformation produced by buckling and the axial plastic elongation caused by yield and growth effect respectively. In addition, the elastic bending deformation was included in the present model. The proposed method was direct and simple. The initial stiffness was maintained constant when capturing the nonlinear behavior of steel braces. Particularly, the plastic rotation can be acquired and provides a direct evaluation on the buckling behavior state. Verifications showed that the axial force versus axial displacement hysteresis loops agreed reasonably well with the experimental data. The brace model was also implemented in a frame, where inelastic response occurred in both the frame and the braces. The numerical results indicated that the present research can simulate complex nonlinear behavior of steel braces, and is an accurate, efficient, and stable algorithm for conducting dynamic analysis when coupled with the state space formulation.