Damage Characteristics,mechanism And Reinforcement Method Of Prefabricated Bridges Vulnerable Components

With the continuous improvement of construction technology,prefabricated assembled bridges have been widely used in modern bridge construction due to their modular prefabrication and on-site assembly features,and their application has reached a considerable scale.However,with the increasing number of prefabricated assembled bridges,structural safety issues have also become more prevalent,and potential hazards have gradually emerged.Therefore,based on a detailed analysis of thousands of prefabricated bridge inspection data,this study conducted research on the damage characteristics,damage mechanisms,repair methods,and design optimization of vulnerable components in prefabricated assembled bridges.The following achievements were obtained:(1)Through the statistical analysis of inspection data from 98 hollow deck bridges(735spans),44 small box girder bridges(1108 spans),and 33 prefabricated T-beam bridges(2293spans),it was found that the most severe damages occur in the hinge joints of hollow deck bridges,transverse diaphragms of small box girders,and transverse diaphragms of prefabricated T-beam bridges,making them the vulnerable components of this type of modular bridge.Through a survey of continuous steel-concrete composite beam bridges,it was found that transverse cracking is prone to occur in the negative moment region of the bridge deck.Through tests on prefabricated segmental piers,it was found that segments near the abutment are prone to damage,making them the vulnerable parts of prefabricated segmental piers.(2)Finite element analysis of the damage to vulnerable components was conducted.The mid-span hinge joint load is the main cause of damage to mid-span hinge joints and transverse diaphragms,while the eccentric load is the main cause of damage to joints and diaphragms on both sides of the bridge axis.The analysis results are consistent with the damage statistics.In the negative moment region of the steel-concrete composite beam,the maximum longitudinal tensile stress occurs under mid-span joint load.In the operation of the prefabricated segmental pier,the pier is subjected to overall compression,and a slight slip occurs at the joints between segments.(3)The method of steel reinforcement for hollow decks and the design optimization suggestions for the layout of transverse diaphragms in hollow decks have improved the lateral connection of prefabricated hollow deck bridges,effectively improving the contact stress of expansion joints and the maximum vertical relative displacement of hollow decks.The method of applying transverse prestressing with CFRP and the design optimization suggestions for Hshaped steel transverse diaphragms have improved the lateral connection of main girders.The design optimization suggestions of applying prestressing force in the negative moment region of steel-concrete composite beams and using UHPC to replace traditional concrete bridge decks have improved the cracking load of the negative moment region of the bridge deck.The design optimization suggestion of using glued joints instead of dry joints for prefabricated segmental piers has avoided the occurrence of openings at the joints and improved the overall stiffness of the piers.