Performance and Design of Composite Beams With Web Openings

Abstract

Fifteen tests to failure were carried out on full scale composite beams with web openings. All beams had ribbed slabs using formed steel deck. Ribs were perpendicular to or parallel to the steel section. The effects of moment-shear ratio, partial composite construction, deck rib orientation, slab thickness, opening shape, opening eccentricity, and modification of the deck over the opening are studied. A strength mode: and three versions of a practical design technique are developed. The model and ! the design techniques are compared with all experimental work on composite beams with web openings. Serviceability criteria are developed. The peak loads attained by composite beams with ribbed slabs at web openings are governed by the failure of the slab. Rib failure occurs in slabs with transverse ribs, while 1 ongi tudinal shear failure occurs in slabs with longitudinal ribs. As the number of shear connectors above the opening and between the opening and the support increases, the failure load increases. The failure of composite beams with ribbed slabs is, in general, ductile. First yield in the steel around the opening does not give an accurate indication of the section capacity. The strength model and the design techniques accurately predict the strength of composite beams at web openings for beams with solid or ribbed slabs.