Structural performance degradation mechanism of concrete bridges in cold regions
In order to study the ultimate bearing capacity of concrete bridges after structural performance degradation in cold regions,prestressed concrete simply supported slab beams retired after 15 years of service in the cold region were taken as the research object.The degradation of concrete was studied using X-ray CT,and the mechanical properties of degraded steel bars and strands were tested.The full-scale bending capacity test of the slab girder was completed,and a 3D nonlinear finite element model was established in ABAQUS to simulate the entire failure process.The results indicate that the logarithm of pore volume in concrete follows a Gumbel distribution,and the parameters of the distribution exhibit a two-stage linear variation with the specimen depth.The overall state of the test girder can be divided into two stages:elastic and plastic.The critical point of the two stages appears at a load of 200 kN,at which point the deflection to span ratio is 1/1236.The ultimate load is 540 kN,and after slippage between the concrete bridge deck pavement and the main girder,the test girder loses its overall bearing capacity.
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