Dynamic Response and Damage Characteristics of Non-newly-built Bridge Pile Foundation Under Horizontal Impact
Bridges crossing water bodies inevitably suffer from damage or defects during service,and the substructure of the bridge is easily damaged by ship impacts,which can lead to safety accidents.To study the dynamic response and damage characteristics of non-newly-built bridge pile foundations under ship collision,a diving exploration of 96 pile foundations of the Han River Bridge in Shaanxi Province was conducted,based on which the damage level of the non-newly-built bridge pile foundations was clarified.The analytic hierarchy process was used to establish a system for evaluating the pile foundation defects of the Han River Bridge,and the evaluation results were compared with the analysis results of on-site exploration.Three types of single pile specimens(new,diseased,and diseased reinforcement)were prepared.A custom-built pendulum impact device was used to conduct horizontal impact tests on three types of single pile specimens,and the dynamic response characteristics of the impact force,concrete strain,displacement,acceleration,and pile damage of the three types of single pile specimens under the same horizontal impact load were compared and analyzed.The results indicate that the established non-newly-built bridge pile foundation damage evaluation system can effectively identify the service status of the Han River Bridge with high structural integrity and normal functional use.The impact process of a single pile can be divided into three stages:peak impact,system separation,and secondary impact.The formation and development of soil wedges around piles reduce the lateral soil resistance,which in turn affects the impact resistance of pile foundations.Only the reinforcement of the exposed ground section of the diseased pile foundation has a limited impact on reducing the damage caused to the pile foundation under horizontal impact loads,and the reinforcement effect is not significant.The findings of the study can provide a reference for the design and construction of collision prevention structures for non-newly-built bridges crossing water bodies.
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