Influence of slab connection on slenderness effects in slender rectangular RC beams

Abstract

Slender reinforced concrete (RC) beams with narrow rectangular sections and no integral slab connections are commonly encountered in pre-cast construction, fascia and roof elements in buildings. Long and slender concrete beams are also encountered in prestressed concrete applications, typically in bridge girders, and instability failure have sometimes been observed during erection. More commonly, in concrete buildings, tanks, etc., slabs are integrally connected to the beams. Slenderness effects are not likely to be of concern if such slabs are located in the flexural compression zone of the beams. However, if the beams are very slender, and the slabs are located near the flexural tension zone, then slenderness effects can still be of significance, and need to be reckoned with in design. Such cases are commonly encountered in balcony construction and long cantilever beams, where “T-beam” action is absent and the beams are designed as rectangular beams in practice. This paper reports the results of experiments conducted to study the effect of slab connection on the flexural tension side of narrow rectangular beams. The test results establish that the presence of an integrally connected slab in the flexural tension zone enhances flexural stiffness, mainly in the vertical plane.