Experimental assessment of seismic performance of panel zone in built-up box columns with corner welded joints

Application of box columns in steel moment frames is very common due to its bidirectional flexural resistance and also its shape which provides suitable surfaces for connection of beams in both directions. In Iran, because of limited availability of rectangular HSS sections, typically built-up box columns are applied which are fabricated by welding four steel plates to each other. According to seismic provisions, within a zone adjacent to the connection point of beam to column, flange and web plates of built-up box columns shall be joined by CJP groove welds. Because of the cost and difficulty of groove welding and concerns about achieving full penetration of weld in box sections, besides the common practice for fabrication of box sections in Iran by means of fillet-welded corner-outside joints, in this research seismic performance of moment connections between I-Shape beams and built-up box columns with corner welded joints was investigated experimentally. For this purpose, two specimens representative of special moment frames and two specimens representative of intermediate moment frames, all fabricated by built-up box columns using fillet welds or CJP groove welds, were designed and investigated. Investigation of the seismic performance of the specimens has been performed thru applying the cyclic load pattern presented in AISC341-16 standard. The results showed the capability of all 4 samples to satisfy the requirements for the required drift angle according to the specified load pattern.