Study of Bracing Force Acting at Mid-Span of Beam of Single-Span Portal Frame

The brace at the mid-span of beam of portal frame provides lateral constraint and improves its overall stability. By the nonlinear finite element method, the influences of structural parameters on the required bracing force for the beam bearing ultimate load were investigated when only one brace acting on the upper flange of beam at mid-span. The bracing force is correlated to the failure mode and configuration of beam of portal frame. The failure of beam trends to be controlled by the strength and the required bracing force increases when the stiffness of column increases. The required bracing force corresponding to the beam subjected to the ultimate load increases when the span of beam or the width of beam flange increases. The research work can be used as reference for the brace design for beam of portal frame.