Stress Analyses of Deep Plate Girders Used at Oil and Gas Facilities with Rectangular Web Penetrations

Rectangular openings in structural members are used to allow the passage of services. Special design considerations are required to compensate for the reduction in stiffness and to minimize fatigue cracks in the web. The paper investigates the behavior of deep plate girders with rectangular openings with applications to oil and gas facilities. An efficient numerical procedure is first presented for analysis of webs with rectangular penetrations. The limitations of the current AISC guidelines and Canadian design procedures are also highlighted. Recommendations are proposed for structural engineers to minimize web stresses in the girder. The influence of these penetrations on the performance of the plate girder is also illustrated for several loading conditions. It is shown that for openings with aspect ratios $(\alpha /\beta )>1$, the stress decreases as the opening radius of curvature ($r$) increases. Also, the location of the maximum stress is largely influenced by the opening aspect ratio ($\alpha /\beta$). It is also shown that a slow increase in the web maximum stress results when the opening curvature $(r)<40\mathrm{mm}$. For plate girders under shear loading, the web stress decreases by increasing the opening curvature ($r$).