Concrete Bridge Bearing Capacity Degradation Based on Crack Patterns
After the long-term service,concrete bridges undergo structural integrity variation and substantial degradation of material properties.The bridge structure needs to be evaluated and analyzed.This study selected an in-service concrete bridge and employed finite element technology to establish the bridge model.The discrete model was used for crack modeling,and the flexural simulation was conducted for analysis and calculation.Based on the types and distribution of stress-induced cracks,the study investigated the influence of flexural and shear cracks in different morphologies on the failure behavior and degradation of concrete bridge structure bearing capacity.The result indicates that the presence of flexural cracks has little effect on the structural failure behavior of bridge.With different crack heights and widths,the load-displacement curve shows minimal variation.Before structural failure,the bottom longitudinal reinforcement and the stirrups at crack location reach the yield state.The cracks distribute uniformly and decrease from the loading point to the height of both ends.The height of shear cracks significantly affects the failure behavior of bridge structure.When the height of shear fracture is high,the load-displacement curve decreases obviously.The shear cracks'width has little effect on the bearing capacity of bridge structure.The load-displacement curves remain essentially consistent with different widths.Before structural failure,the bottom longitudinal reinforcement does not reach the yield state.The cracks at the shear crack location penetrating through beam lead to structural failure,while the rest of beam has a relatively lower height of cracking.The formula for structural stiffness reduction is introduced considering the deformation of cracked bridge structure consists of two parts.Based on the relevant standard,the formula for residual bearing capacity calculation is derived,and the selected bridge bearing capacity is verified with the deviation within 5％.
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