Testing And Safety Assessment Of Existing Reinforced Concrete Arch Bridges Based On Load Test

Reinforced Concrete arch bridge is the most common bridge type in small and medium-sized towns in southwest China in the 1980-1990 years of the last century.However,due to the limitations of design and construction procedures at that time and environmental erosion since long-term operation,many arch bridges in these areas have problems such as insufficient carrying capacity,appearance diseases and structural damage,in order to enable these arch bridges to operate safely and give full play to economic and social benefits,It is urgent to test it and evaluate its security.In this paper,a reinforced concrete arch bridge in southwest China is used as the research object,and its detection and safety evaluation is carried out based on the load test.The main contents of the thesis are as follows:(1)Disease survey statistics and bridge technical status assessment.By means of appearance investigation and nondestructive testing,the disease investigation of the Arch Bridge is carried out,and combined with the results of the linear data of the bridge structure obtained by the total station,the weight of the component is distributed qualitatively by stratified comprehensive evaluation method,and the evaluation level of bridge technical condition is obtained to prepare for further evaluation.(2)A preliminary evaluation of the bearing capacity and safety of the bridge is made by a static load test.According to the design data of the arch bridge,the bridge model is established by using the finite element software Midas/Civil.Static calculation and eigenvalue analysis of the model provides a theoretical basis for a static load test and pulsating test.This paper compares and analyzes the results of static load test with the results of finite element simulation,makes a preliminary evaluation of bridge bearing capacity and safety according to the data of deflection and strain,and emphatically studies the synergy between deflection checking coefficient and strain checking coefficient,and probes into who can reflect the working state of the bridge when the coordination degree of the two parameters is not high.(3)The dynamic working performance of the bridge is evaluated by the dynamic load test.The transmission rate method is used to identify the output response under the environment excitation,and the identification results are compared with the finite element simulation results to evaluate the modal parameters of the structure.Through the data analysis of the barrier-free driving and braking test,the dynamic characteristic parameters of the bridge are obtained,and then the working state of the bridge under dynamic load is evaluated.(4)Structure safety is evaluated after the model is modified based on the current situation of the bridge.The self-vibration frequency sensitivity analysis of the model material characteristics and geometrical parameters is carried out,and then the parameters are adjusted so that the self-vibration frequency of the model is more in line with the measured results under the environmental response,at which time the model can better reflect the status.The new model is used to evaluate the structural security,and the future bearing capacity of the structure can be predicted by the parameter influence trend.