COMMENTARY ON PROPOSED SPECIFICATION FOR STRUCTURAL-STEEL BEAMS WITH WEB OPENINGS (WITH DESIGN EXAMPLE)

This commentary complements the "Proposed Specification for Structural Steel Beams with Web Openings." The specification follows load and resistance factor design (LRFD) philosophy, and may be adopted as a chapter in a larger specification. Basic design procedures involve determination of maximum nominal flexural capacity, maximum nominal shear capacity, and interaction of flexure and shear. The maximum nominal flexural capacity is calculated using standard strength procedures for both composite and noncomposite sections, taking into account the loss of material within the web. The maximum nominal shear capacity is based on a simplified four-hinge mechanism, with one hinge at each corner of the opening. The general design approach is identical for composite and noncomposite members, with or without opening reinforcement. The design procedures apply only to compact sections. Additional criteria are applied to ensure ductile behavior and performance in accordance with the design expressions. The procedures apply to both rectangular and circular openings. Criteria for placement of concentrated loads and positioning of openings are included, as are detailing requirements for opening and slab reinforcement.