Fatigue assessment of a full-scale composite box-girder with corrugated-steel-webs and concrete-filled-tubular flange

Abstract

Performance and aesthetic considerations push the bridge industry towards new structural solutions. A new type of composite box girder with corrugated steel webs was proposed, which utilizes concrete-filled wide-flat steel tube replacing concrete slab as bottom flange. This new design may still be susceptible to fatigue due to its complicated configuration and inevitable repeated heavy traffic loads. Therefore, this research presented a full-scale fatigue test and numerical study of this new composite girder through four-point bending. The test results demonstrated that even under a rather low stress level, the composite girder still sustains fatigue damage under a very high cycles of 9.84 million, which leads to failure as multi cracks have initiated and propagated at top and bottom surface of steel tube around mid-span location. Assessed by the structural stress approach fully relying on finite element analysis (FEA) results and modified version combining FEA results with measurement data, the cumulative damages for all fatigue-sensitive details of test girder are respectively lower and higher than the failure standard 1.0. This indicates that the modified method is in consistent with experimental results, while the original one is not. Accordingly, it is advisable to combine FEA results with measurement data to evaluate fatigue-sensitive details of this composite girder.