Research On Perceptual Warning Method Of Ship Collision With Bridge Superstructure In Zhujiang River System

Based on the analysis of the characteristics of water level,ships and bridges in the Pearl River system,and on the basis of the existing monitoring and early warning methods of ship collision,this paper analyzes the risk of ship collision of bridges in zhe Zhujiang River System in combination with the characteristics of large-scale bridges and densely distributed small and medium-sized bridges in zhe Zhujiang River System,and carries out the research on the perception and damage methods of ship collision of bridges and superstructure of bridges in the Zhujiang River System.The main work and conclusions are as follows:(1)Based on the dynamic response,the sensing scheme of the superstructure of the bridge is proposed: arrange acceleration sensors at the specific position of the bridge in advance,use the real-time amplitude of the acceleration sensors to sense the impact of the superstructure of the bridge by ships;roughly judge the impact position by the acceleration amplitude and distribution rules of each measuring point;reduce the stiffness after the impact damage of the superstructure will occur Based on the dynamic principle of the change of natural vibration characteristics,the equation expression between ship collision damage and multi-level natural frequency is obtained,and the identification method of ship collision damage of superstructure is discussed according to the multilevel frequency change law.(2)The ship collision perception threshold is defined as the response value of the maximum lateral dynamic response of non ship collision and the minimum impact response of typical ship at a certain assurance rate.In general,the maximum lateral dynamic response of non ship collision is caused by the set regular wind load and driving vibration.Based on this,a calculation method of ship collision perception threshold for typical bridges in Pearl River system is proposed.Based on the principle that the dynamic response of the structure is related to the magnitude and position of the excitation under the action of dynamic load,the acceleration response amplitudes of the main beam measuring points under various ship collision conditions are analyzed,and the variation and distribution rules of the acceleration response amplitudes under different ship collision positions and collision forces are obtained.A ship collision sensing algorithm based on the variation of the acceleration response amplitudes is proposed.(3)Based on the dynamic equation between the bridge stiffness matrix and the free vibration frequency,the rules between the different ship collision conditions and the superstructure damage degree are analyzed,and the multi-level modal analysis of the superstructure based on the different assumed damage degree is carried out.The relationship between the superstructure damage degree and the first five order free vibration frequency based on the statistical analysis and the collision position of the ship bridge are proposed by using the least square method According to the relationship between the change of multi-stage natural frequency and the change of natural frequency,the method of damage identification of superstructure collision is explored.(4)Combined with the ship collision sensing method based on the amplitude variation characteristics of bridge dynamic response and the identification method of ship collision damage of bridge superstructure based on the frequency variation characteristics of natural vibration characteristics,the impact simulation test of bridge superstructure is carried out.The dynamic response of the structure under the action of various impact parameters,such as impact mass,impact position and impact velocity,is simulated by pendulum.The experimental results show that the method proposed in this paper can effectively perceive the impact of superstructure,and can preliminarily identify the magnitude and location of impact force,which verifies the feasibility of the method of ship impact perception and damage identification based on the dynamic response of bridge.