Inverse Analysis And Protection Countermeasure Study Of Bridge Pier Under Wave Excitation Response

With the rapid development of economy and transportation industry in our country, the establishment of regional transportation network becomes urgent. Therefore construction and development of sea or river crossing bridge should be accelerated. However, wave load becomes external load has to be considered in the structural design of sea or river crossing bridge as it is one of the most serious natural disasters for human life and property security. Therefore it is significant to carry out the analysis of pier vibration under wave excitation and braking measure which is also scientific research personnel and bridge designers will face.This article refers to several subjects which covers ocean engineering wave mechanics, bridge engineering, bridge hydrology and hydraulics, structural dynamics, vibration mechanics, introduction to spectral analysis and the random vibration, fluid dynamics, numerical analysis, probability statistics, structure finite element analysis, disaster prevention and mitigation engineering, fluid-structure interaction dynamics and etc. Its main research contents and achievements are shown as follows:1) Establish single degree of freedom wave force time history curve on the basis of the wave spectrum on account of the linear superposition method. Meanwhile, converting equivalent wave force numerical calculation simplification formula is established taking isolated pier cantilever beam as mechanics characteristic. By means of examples proving, wave force calculated by this simplified formula could cater for accuracy requirement which provides a convenient and simple calculation method for the random wave force research.2)Vibration response spectrum chain recursion formula changing with trigonometric function in equal time intervals is established by reference to the basic ideas of solving response spectrum interpolation method at home and abroad and combining with the characteristics of wave force time-history curve so that practical wave is simulated to do contrastive analysis on response spectrum accuracy. It shows that this method is of simplicity, speediness and accuracy which will provide effective calculating analysis method for the wave resistance design of bridge piers.3) Use full amount compensation composite inversion method for the first time to do physical parameters identification and unknown wave force inversion on bridge pier under the condition of some unknown wave input. It further deduces that wave force time-history acting on each node is approximate to be complete domain correlation leaving out wave drag force. The improved composite inversion algorithm is constructed under the condition of unknown wave input and unknown load effect on the peak combining probability "statistical averaging method" and "elimination method" with it. Through verification, this provides reference for bridge damage identification.4) In order to comprehensively discuss the force and response features of deepwater pier under various environmental load effects, fluid-structure coupling model of finite element software ANSYS is applied to analyze the wave force response of deepwater pier under the influence of earthquake, flow velocity and wind load. Additional mass and fluid-structure coupling effect are also taken into account. Analysis and comparison results show that comprehensive consideration of influences of all environmental factors on deepwater bridge pier makes structural design be safer, more economical and reasonable.5) Take the weak link chain-cutting disaster mitigation idea in the chain-styled theory of the disaster as orientation and fluid theory to be basis, this paper refers to structural wind resistance and bridge pier scour prevention mechanism, puts protective measure which protects bridge piers spanning rivers and seas from damaging of wave and other environmental loads on reducing resisting and elevating force of cylinder streaming around and proposes three pieces of measures to prevent cylinder piers from flowing around. It verifies that these three measures are effective and applicative and provide reference for wading bridge pier protection.