Impact of Flange Holes on Flexural Behavior of Steel Beams—An Experimental Investigation

Holes in the flanges of steel beams and girders are commonly required for bolted connections and can influence both flexural strength and rotational ductility. Although flange-hole effects have been investigated previously, the experimental basis of several traditional provisions was developed using older steels with relatively low yield-to-ultimate strength ratios. Current design specifications differ considerably in their treatment of open and fastener-filled flange holes. In particular, the relationship between flange-area reduction, flexural resistance, rotational ductility, and net-section fracture in modern structural steels remains insufficiently quantified. This study addresses these issues through tests of twenty-five full-scale W200 × 42 beams fabricated from ASTM A992 steel with a measured (Fy/Fu) ratio of approximately 0.77. The test program included solid beams, beams with open holes in the tension flange, beams with open holes in both flanges, and beams with fastener-filled holes in both flanges. The results demonstrate that flange-area reduction affected rotational ductility more severely than flexural strength. For the most severe tension-flange reduction investigated (Afn/Afg = 0.52), the maximum moment decreased by 16.8% relative to the solid beams’average maximum moment, whereas the total rotation capacity (Ry) decreased by 77.2%. The experimental capacities were also compared with predictions from AISC-LRFD, AASHTO-LRFD, CAN/CSA-S16, and AS 4100. Based on the observed strength and failure behavior, a design framework considering gross-section flexural resistance and modified net-section fracture resistance as competing limit states is proposed. Across the investigated specimens, the ratio of measured maximum moment to the proposed design moment (Mm/Mdp) ranged from 1.21 to 1.47, indicating conservative predictions within the experimental range considered.