Study on Microscopic Damage of Anti-disturbance Concrete during Splicing Maintenance under Normal Traffic Condition
The connection of widening bridge needs to be carried out under the normal traffic condition.For the anti-disturbance concrete of the splicing zone,it is still in the concrete curing period,and its performance may be affected.Through on-site detection,only the macroscopic damage of the splicing zone can be found.The microscopic damage inside the concrete of splicing zone caused by vehicle-bridge coupling vibration is difficult to observe.Based on finite element simulation analysis and CT scanning technology,the stress distribution and actual damage of the concrete splicing zone are studied.Firstly,the simulation analysis model of widening bridge is established by the ANSYS finite element software.Based on different working conditions,the stress characteristics of widening bridge splicing zone are clarified.Secondly,the key positions of the splicing zone are selected based on the simulation results.The mid-span and quarter-point sections of bridge are selected as the key section.The concrete core samples at the joint center line and interface from the key section are obtained.The appearance of the concrete core samples is observed as well.Finally,the CT scanning technology is applied to obtain the tomography observation image of core sample.Based on the obtained scanning data,the internal structure of the core sample is reconstructed in three dimensions.The aggregate distribution and crack propagation of the splicing concrete after disturbed vibration are analyzed.The result shows that(1)The lateral force of the anti-disturbance concrete in splicing zone under various working conditions are mainly compression at the top of the joint and tension at the bottom of the joint.Only near the supporting point position,the stress characteristics of the joint section have the tendency of eccentric compression.The transverse force of splicing zone can meet the strength limit of anti-disturbance concrete material.(2)For the core sample from the center line of the splicing zone,there is no obvious crack inside the core sample,and the internal aggregate and fiber are evenly distributed.The steel fibers at the top of the splicing zone are distributed horizontally,and the fibers at the bottom are distributed obliquely.(3)For the core sample from the interface position,there is a micro-fracture with a certain depth on the top interface of the core sample,and the fracture depth is less than 1 cm.The micro-fracture has little effect on the interface performance of the splicing zone.The steel fibers near the interface have a certain sinking trend and the fibers are mostly obliquely distributed.(4)In the case of bridge splicing under normal traffic condition,the vehicle-bridge coupling vibration will cause the orientation of steel fiber in the splicing zone,the steel fiber will even sink,that will directly reduce the material tensile properties of splicing zone.
bridge engineeringmicroscopic damageCT scananti-disturbance concretewidening bridgesplicing under normal traffic condition
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