Experimental Tests on Concrete Wall-Steel Beam Connections

Abstract

Structural systems consisting of concrete walls and steel frames have recently become popular for New Zealand residential and commercial building applications. However, the seismic performance of the connections in such mixed-material structural systems is not well investigated and may be a cause of concern. Previous studies focused on connections between steel gravity frames and concrete core walls, whereas New Zealand buildings tend to use a wide variety of wall configurations and steel framing systems. Furthermore, current building design standards are compartmentalised according to material; therefore, mixed-material building design is not explicitly addressed. In this study, experimental tests were conducted on four full-scale concrete wall-steel beam connections to quantify seismic performance and validate potential failure modes. A typical connection detailing was developed using existing New Zealand design procedures. The connection consisted of a bolted steel web plate and headed stud anchors. The influences of floor starters, slotted holes in the web plate, and bent reinforcing bar anchors were also investigated. Preliminary test results indicated that although the connection was designed for ductile failure through web plate yielding, all four specimens failed by concrete breakout. The presence of floor starters and a floor slab hastened the occurrence of concrete breakout, which was partially alleviated by using slotted holes in the web plate and substituting headed studs with bent reinforcing bar anchors. This paper also describes how the test results can be used as a basis for further studies on concrete wall-steel beam connections and to develop an improved design procedure for concrete wall-steel beam connections.