Experimental Investigation of Cyclic Loading Performance of Stubby Steel Braces

Steel braces with small slenderness ratio and small width-to-thickness ratio which were termed as stubby steel braces are believed to exhibit superior ductility. However, the belief is supported by limited experimental evidence. Therefore, 27 steel braces with I-Shaped, round-HSS or square-HSS sections subjected to symmetric-amplitude cyclic loading up to plus-minus 3% in axial deformation were comparatively examined. Among the specimens, 5 stubby steel braces had both a very small slenderness ratio of 10 to 30 and a very small width-to-thickness ratio which qualify them as the most ductile “BA” and “Highly Ductile” braces, according to the Building Standard Law of Japan and AISC Seismic Provisions for Structural Steel Buildings, respectively. As a result, the limiting effective slenderness ratio to define ductile stubby steel braces based on the the Building Standard Law of Japan, was not effective. The limiting width-thickness ratios stipulated in the AISC Seismic Provisions for Structural Steel Buildings has a potential applicability to predict the ductile steel braces. Contour lines of the effective slenderness ratio and the width-to-thickness ratio visually indicated that the stubby steel braces would maintain the post-buckling strength as 0.3 times the buckling strength. The Building Standard Law of Japan serves the limiting effective slenderness ratios as valuable guideline for evaluating the contraction of steel braces at the occurrence of local buckling.