Research On Nonlinear Characteristics Of Vehicle-bridge Coupled Vibration Response Based On The Delay Vector Variance Algorithm

Highway bridge as an important part of traffic facilities which plays an important role in promoting the national economy.Vehicle passes the bridge that will cause the effect of vehicle-bridge coupled vibration,and through the motivation by the moving vehicle the vehicle-bridge coupled vibration system's analysis of bridge's damage identification which is gradually get to the attention of the academia.Only by understanding the dynamic properties of bridge under vehicle load,we can put forward the targeted stimulation and test scheme,and identify the damage of bridge based on vehicle-bridge coupled vibration response.And the fully cognition to the nonlinear characteristics of the vehicle-bridge coupled vibration response and to find out the causes of its nonlinear is the premise to realize damage identification.The dynamic response of highway bridges based on vehicle-bridge coupled vibration mainly concentrated in the intact bridge,and most of the analysis of the impact of the bridge displacement or acceleration coefficient to study the dynamic characteristics of bridge.Using the bridge vibration impact coefficient to describe the dynamic performance of the vehicle which of the role relation is too simplified and does not conform to the actual,and the impact coefficient reflecting the maximum dynamic effect can't show the overall situation.For the actual bridge,the dynamic displacement measurement is difficult to meet the accuracy requirements.So,this thesis establishes vehicle-bridge coupled vibration model,analyze the obtained vibration acceleration time history response of the damaged bridge,and analyze nonlinear characteristics of the bridge's dynamic response based on delay vector variance algorithm.In this thesis,the main work is as follows:1.The thesis puts forward using delay Vector Variance(Delay Vector Variance,DVV)algorithm to analyze the vehicle-bridge coupled vibration response,researches nonlinear law of bridge vibration acceleration time history response based on rough of road and damage of bridge.And the thesis puts forward four nonlinear quantitative indexes,which quantifies the nonlinear characteristics of bridge vibration.2.A simply-supported beam is as example,which uses the time-delay vector variance method to analyze the nonlinear effects of vibration response of the bridge,studying the vehicle speed,vehicle weight,surface roughness and damage degree to the damage bridge vibration acceleration signal's nonlinear effect.By the simple supported beam's example of the simulation analysis,and through the comparison and analysis of 1/4 span and midspan node's change of acceleration's nonlinearity,it gets that by the increasing of the speed,the response of the acceleration's nonlinearity presents the regularity that is increase-decrease-increase.By the increasing of the vehicle weight's and road surface roughness' s degree,the acceleration's nonlinearity is increasing.But the change of the damage degree has no effect on the response of the acceleration's nonlinearity.3.A three span continuous prestressed concrete box girder bridge is as an example,which analyzes the vehicle-bridge coupled vibration response of the bridge after cracking,and compares the finite element stiffness degradation,open and breathing cracks under three different damage simulation ways to the results of the simulation that the bridge side mainspan node's and mainspan node's nonlinear law of acceleration.The results show that with the increase of damage,bridge's acceleration response of nonlinear degree increases;When damage degree is same,the nonlinear acceleration response under the three different damage model for bridge,the turn is: breathing cracks > open cracks > element stiffness reduction;Mainspan's node in the acceleration response of nonlinear is greater than the side mainspan's node;The nonlinearity of quantitative index S is accurately under different working conditions to descript of the nonlinear degree of change.