Exact distortional behaviour of single-box multicell curved composite box girders with corrugated steel webs in the elastic stage

Abstract

The distortional effect in a curved composite box girder with corrugated steel webs (CCBG-CSWs) generated by the combined action of an eccentric load and axis curvature is apparent owing to the thin steel web. The distortional effect in a single-box girder with multicell cross-section is more complex than that with a single-cell cross-section; this is owing to the various distortion modes, which can be classified into first and second distortions. Herein, analytical solutions for both the first and second distortional effects, as well as for the case with diaphragms, were derived based on the energy variational principle and solved using the beam on elastic foundation (B.E.F.) analogy for single-box, multicell, and simply-supported CCBG-CSWs in the elastic stage. Experiments and finite element analyses were performed to validate the analytical solutions. The ratios of the first to second distortional angle (stress) were approximately 2:1 (5.25:1) and 2.8:1 (8:1) for the double-cell and triple-cell sections, respectively, indicating that the second distortional effect cannot be ignored for the single-box multicell CCBG-CSWs. A parametric study regarding the diaphragm number, span–radius ratio, and span demonstrates that the distortional stress ratio (ratio of the summation of the first and second distortional normal stresses to the flexural normal stress) exponentially decreases as the diaphragm number and span increase, and linearly increases as the span–radius ratio increases, however, when the diaphragm number is sufficient, the distortional stress ratio is considered almost constant. Based on the parametric study, a practical equation considering both the first and second distortions was proposed using the regression analysis method to predict the diaphragm space of multicell CCBG-CSWs with the desired distortional stress ratio as the control index.