LAUSR

Steel structures with moment-resisting frame exhibit acceptable ductility against heavy seismic loads. However, providing the required stiffness and strength by moment-resisting frames is a difficult task, especially in high-rise buildings. The aim of this study is to investigate the effect of axial load on the performance of steel structures using moment-resisting frames and braced frames with buckling-restrained knee-bracing systems. For this purpose, two experimental specimens with a 1:3 scale were subjected to monotonic lateral loading. The first specimen was a steel frame with rigid connections. Buckling-restrained knee bracing and shear plates were added to the first specimen and the second specimen was constructed. Experimental results showed that the presence of a buckling-restrained knee bracing not only enhances the strength and stiffness of the specimen also increases its ductility significantly. The results of finite-element modelling and the effect of axial load presence on the seismic characteristics of each sample were investigated. The outcomes of study showed that the presence of an axial load of more than 50% of the column capacity significantly reduces the seismic characteristics.