Study On Test Detection And Reinforcement Technology Of Small Span Arch Bridge

With the development of transportation and economy in China,the traffic volume is increasing,the number of heavy vehicles is increasing,and the requirement for the capacity of the bridges is becoming higher and higher.During the construction of highway in the1950 s and 1970 s,a large number of middle and small span masonry arch bridges were built in China.With the increase of traffic volume,the increase of vehicle load,and the effect of natural factors in service period,many bridges have appeared various diseases and damages,which can not meet the needs of the development of transportation.It is of great social and economic benefit to determine the actual use status of this kind of bridge by testing,and to restore and improve the use function of the bridge by adopting suitable,economical and reasonable methods.In this paper,based on the engineering example of Tongjia bridge detection and reinforcement,through literature reading,on-the-spot Investigation and detection under the condition of lacking of design drawings and data,the Disease Investigation,cause analysis and technical evaluation of the bridge are carried out,and the reinforcement scheme of the enlarged section of the main arch is worked out according to the actual condition and site condition of the bridge,using the finite element software to calculate,analyze and compare the bridge structure before and after the reinforcement,carry out the load test after the reinforcement,compare and analyze the test data and the result of the finite element calculation,combine the request of the relevant code,the main work contents and conclusions are as follows:(1)To investigate the bridge disease and cause analysis,and to measure the bridge structure size on site,the technical conditions and structural parameters of the bridge are determined to provide a basis for the structural calculation of reinforcement design.(2)The Midas/civil finite element software is used to establish the bridge structure model and draw up the reinforcement plan of the main arch’s enlarged section.The calculation results show that the safety reserve of the bridge structure before and after reinforcement is increased from 0.83 to 1.87,the bearing capacity has been improved obviously,and the reinforcement scheme is reasonable.(3)The static and dynamic load tests of the strengthened bridge are carried out.The results of load test show that the strain check coefficient of each main section is 0.42～0.79,the maximum relative residual strain is 18.18% after unloading,the deflection check coefficient of each main section is 0.53～0.80,and the maximum relative residual displacement is 15.38% after unloading The ratio of the measured first-order frequency to the calculated value is 1.54,and the stress of every section of the main arch is obviously decreased after reinforcement,the decrease range is up to 37%.After reinforcement,the bridge can meet the requirements of highway-class II vehicle load.The practice of detection and reinforcement of Tongjia Bridge is a successful engineering case,which can be used as a reference for similar small Span Masonry Arch Bridge.