Analysis On Failure Mode And Bearing Capacity Of A Reinforced Concrete Frame Culvert

A unique end reinforcement of the reinforced concrete frame culvert structures are widely used in parts of the USA, this kind of structure is mainly bearing vehicle wheel pressure etc.(moving load). These culverts has been used nearly half a century, Although part of the culverts emerged Slight longitudinal cracks at the bottom of the structures, but there has never been a major degradation and damage performance. In order to furtherly clarify the failure pattern and bearing capacity of these culvert structures, providing technical support for the follow-up maintenance or reinforcement work of this kind of structure, the research cooperated with America University of Delaware,researchingthefailuremodes andthebearingcapacityofthestructure.On the basis the findings of experimental research, this paper analyses the whole failure process, failure modes and bearing capacity of the four typical specimens using the finite element.By choosing appropriate material constitutive relations, combining with concrete damage plasticity model of ABAQUS, studied on determination of concrete damage plastic constitutive parameters,and comparing the test and finite element simulation results, verifying the rationality of the selected parameters. Based on the finite element model of the specimens, analised the whole process of the four typical specimens, result shows that the failure form of specimens are all for shear compression failure withing the concentrated loading, two symmetrical loading and two asymmetrical loading, and the bearing capacity of specimen under two symmetrical loading was about two times in the span under concentrated load. The simulation results show that the width of large width specimen failure modes turned shear compression failure into punching failure, vertical displacement changes little, but the bearing capacity is greatly improved. For the four typical specimens, the analysis shows that, when the load reached about failure load of 50%, the end of the bentbardid not appearobvioustension, thecurvedsteelhasdelayedthe failureoftheendconcrete.Respectively, the bearing capacity of specimens were calculated and analyzed based on the calculation theory and the assumption of the framework plastic hinge. Result shows that, for the flexural capacity, the calculation results obtained codes are conservative, while the frame calculation result of theory are in good agreement with the test results. For the shear strength of specimens, AASHTO MCFT using the modified compression field theory calculation results obtained better accuracy. Finally, the effective widths of the specimen were studied, an improved algorithm is proposed, and based on the improved effective width, established the calculation formulaofthebearingcapacityofthespecimens.