Numerical Code-Based Assessment of Live Load Patterning Effect on Bending Moment Envelopes in Reinforced Concrete Beam-Column Frames

Abstract

This study evaluates the influence of slab idealisation and live-load pattern on the bending-moment response of a continuous reinforced-concrete subframe using Robot Structural Analysis Professional (RSAP), using manual analysis to BS 8110 as the reference. The objectives were to establish mesh convergence for the analytical shell model, compare the internal continuous beam and column responses of the manual, cladding and analytical shell models, and quantify their differences. Mesh refinement showed that the shell solution was practically converged at 0.25 m; refinement from 0.25 to 0.125 m changed the span 1–2 and interior-support moments by only 0.10% and 0.13%, respectively. The cladding model closely reproduced the manual beam results, with differences of 2.76% for span 1–2, 5.35% for span 2–3 and 0.48% at the interior support. In contrast, the shell model produced reductions of 18.49%, 28.59% and 28.02%, respectively. The shell model also increased the interior-column axial load by 23.06%, while reducing the column top moment by 16.90%. The findings indicate that the observed differences are associated with different structural load-transfer mechanisms rather than mesh refinement alone. The study recommends converged FE models with independent equilibrium and benchmark checks and selection of slab idealisation according to the structural behaviour being represented.