Analysis of concrete box beams using small computer capacity

Following the generalized coordinate method of Vlasov, simple beam theory has been extended to treat torsional, distortional, and shear lag effects in straight, thin-walled box beams of uniform section. Single-cell or multicell sections with side cantilevers can be analysed, and the structure can be single-span or continuous. An example suitable for use in design is given, and all the calculations have been performed on a nonprogrammable hand calculator. The method is suitable for quick preliminary design and for reassessment of load capacity of a bridge. Comparisons are made with the results of finite strip computations. It is expected that when the method of hand analysis is programmed, computing times will be so short that interactive design procedures will become feasible, making it possible to develop relatively simple design rules which consider adequately the types of structural action specific to box beams. A physical understanding of box beam behaviour is facilitated by the use of the theory given here. As the elastic solution developed satisfies equilibrium, it can be factored to give a lower bound to the collapse load, for use in limit state design.