LATERAL RESISTANCE OF CHEVRON-BRACED FRAMES WITH STRONG BEAMS

The elastic-plastic analysis was made for chevron-braced frames with strong beams, the slenderness and inclination of a brace are varied and the beams are strengthened with four different levels. The results showed that strong beams can delay the degradation of the compressed brace’s strength and allow the tensile brace yield, leading to the chevron braces’ peak strength over the buckling strength. Formulas for the peak strength and the overstrength factor of chevron braces are proposed. It is found that the braces with moderate slenderness experience a sharp drop in the lateral load immediately after the peak strength is reached, showing the worst seismic behavior. Formulas for predicting the drift at buckling of braces in compress and yielding of braces in tension are suggested. Equations for predicting the degradation of the braces’ compressive capacity and the unbalanced force supported by beams with a drift ratio are also proposed. All proposed equations are compared with FEM results, showing excellent agreement.