Static and Dynamic Behavior of Steel Braces under Cyclic Displacement

Abstract

The nonlinear static and dynamic responses of individual steel braces under cyclic end displacement are studied in this paper using a fiber-type beam-column model that employs a realistic hysteretic stress-strain law and includes the effect of large displacement, strain hardening, gradual spread of yielding, and proper coupling of the axial and flexural yielding. The study considers square tube braces of different sizes and end conditions, and focuses on the effect of internal inertia as well as the magnitude and distribution of the fiber strain in the members. It is found that the importance of inertia depends on the slenderness of the members and the frequency of the end displacement input. Under certain conditions, the effect of inertia can be very significant and its inclusion can lead to deformation modes fundamentally different from those predicted by quasi-static analysis. The inelastic deformation in the braces is highly concentrated and is affected by factors including member size, end conditions, and the number of load cycles.