Research On Performance Of Concrete Filled Cfrp Reinforced Aluminum Alloy Tube Stub Columns Under Axial Compression

With the development of society today,Bridges have become an indispensable traffic artery in our life.In the construction and service of Bridges,they will suffer from the negative impact of environment,people,vehicles and earthquakes,resulting in structural damage and reduced bearing capacity.It is necessary to monitor the health of the bridge in order to ensure that the bridge will not break during service,causing casualties and losses.In 2004,Yang,the author puts forward the concept of indirect measurement method,which don’t have to install the sensor on the bridge,but installed on the vehicle,the vehicle passes through the bridge for the response of the vehicle information,in a moving vehicle acceleration response signal is extracted and the response of the bridge related,then the response data to analyze it,get bridge modal information processing.Compared with the traditional method,this method is convenient,fast,economical and safe,so it has attracted extensive attention of relevant professional scholars and has become one of the hot topics in the civil engineering industry.Based on the idea of "bridge surface physiogny",Professor Zhou Zhixiang of Chongqing Jiaotong University proposed "WWWQ bridge safety patrol truck",and adopted different technical routes and methods such as "Look,smell,ask and cut" as a branch of bridge surface physiogny to realize bridge detection.In this paper,the method of bridge structure state estimation based on the vibration response of moving vehicles is the "cut" of it.The method is to obtain the bridge damage related estimation index based on the indirect measurement method,and use the index to estimate the bridge structure state.The bridge state estimation can be realized by using the response signal of the bridge structure under working condition without interrupting traffic.The main research work and results are as follows:1.It introduces the analytic solution theory of bridge frequency extraction based on the bridge response of moving vehicle,the numerical analysis theory of moving vehicle bridge model based on VBI element,and the relevant signal processing technology theory.On this basis,an analytical solution theory for estimating the state of bridge structure by indirect measurement method is proposed.The results show that the damage information of bridge structures can be estimated by using the response information of moving vehicles.2.ABAQUS software was used to establish the bridge crossing model of the mobile vehicle and extract the response of the vehicle.The bridge frequency and vibration mode were extracted through analysis of the data.The influence factors of the first-order vibration mode of the bridge are analyzed,mainly aiming at the influence of noise,road roughness,vehicle crossing speed and vehicle driving frequency.The analysis shows that under the conditions of 10% and 20% noise,the extracted vibration mode of the bridge beam is in good agreement with the theoretical mode.When the noise is greater than30%,the fitting results begin to become unsatisfactory.Pavement roughness has a negative effect on the extraction of bridge beam vibration mode,that is,the rougher the bridge deck is,the greater the negative effect will be.The speed of the test vehicle is inversely correlated with the precision of modal extraction.The higher the vehicle speed is,the smaller the precision is and the less accurate the vibration mode is.The frequency of the test vehicle should not be close to the first-order frequency of the bridge.Resonance should be avoided,otherwise the error will increase.3.It is proposed to use the curvature of vibration mode as an index to estimate the state of bridge structure.To achieve this purpose,the bridge structure is set up to simulate the working condition of three kinds of damage analysis,respectively,the single damage(damage occurred in 1/4 across different,injury occurred in 1/2)and more damage(damage occurred in the 1/4 span and 1/2 cross),before and after the bridge damage modes diagram,figure curvature mode shapes and modal curvature difference diagram,by comparing the three kinds of sensitivity to the damage.The results show that the damage location of the bridge can not be estimated by mode diagram,and the damage location of the bridge can be estimated by mode curvature diagram and mode curvature difference diagram.In the shape curvature diagram,there is a sudden value at the damage location.In the curve of vibration mode curvature difference,the damage position of the structure appears peak value,while the damage position does not change much.When two damage occurs to the bridge structure,the vibration mode curvature of the structure is still sensitive to the two damaged parts,but when the damage occurs to the place with high vibration mode curvature value,the change of curvature value is more obvious.The method can still be implemented in working Bridges,and the damage location of Bridges can be estimated without obstructing traffic,which is convenient and safe.4.Verify the laboratory model on the basis of numerical value and theory.The modal information of bridge structure can be obtained by using the indirect method.Through the working condition of bridge structure set up three kinds of damage,respectively,the single damage(damage occurred in 1/4 across different,injury occurred in 1/2)and more damage(damage occurred in 1/4 across different and 1/2),the curvature variation of bridge located and the difference between before and after damage value as the estimation index,illustrates the indirect measurement method is used to bridge structure damage location can also be estimated.