Load Test And Carrying Capacity Evaluation Of2×90Meter Multi-rib Reinforced Concrete Arch Bridge

Under the vertical load, not only the vertical react force at the both ends of the archbridge can be aroused, but also the horizontal thrust which can produce axial pressure. Bythe way, the section bending moment can be greatly reduced which can reduce the tensilestress of the section, what’s more, the axial pressure can cancel one part of tensile stress,which can further reduce the tensile stress. Compared with the beam bridge of the same-span,the reduction of the section tensile stress can improve the crossing capacity of arch bridgesand easily realize the large span of bridges.In order to reduce the section size and lighten the mass of the arch, the reinforcedconcrete arch bridges arrange load-bearing bars in the concrete. In the reinforced concretearch bridge, the tensile stress of the section is mainly born by the tensile bars. Thus, theproject quantity of the bridge can be correspondingly reduced, which can effectivelyimprove the economic performance of the arch bridge and enlarge the application arrange ofthe arch bridge. At the same time, the reinforced concrete arch bridge can be easily handledin the architectural art. The reasonable arch system choice and the structural line highlightcan head to the aesthetic effect. The RC arch bridge has the advantages of pretty modeling,light structure, large span and exerting the material characteristics, so this kind of bridgestyle is widely used at home and abroad.However, with the extension of bridge service period and the promotion of the trafficload grades, the RC arch bridges can be bothered with the damage styles such as structuralmember cracks, unrecovered deformation, defects and arch springing concrete cracks, whichlead to the decline of the entire bridge structure use function and the performancedeterioration.To the bridges with diseases, the most reasonable method is to detect the bridgestructure and according to the results assess the bridge service state and the existing bearingcapacity, and then take proper maintenance and reinforcement measures. In the bridgedetection, the static load tests and the dynamic load tests are all evaluated based on the measured static and dynamic parameters. The load test method is highly objective and withreliable assessment results. At present, this is no systematic and perfect load test method forRC arch bridge, so the research method for the load test the assessment of the bearingcapacity of the RC arch bridge which this paper presents is very meaningful.This paper is based on a practical project of one2×90meter multi-rib RC arch bridgeand mainly conducts the following research work:1. It states the measure method of the dynamic parameters and impact coefficient of thelarge-span RC arch bridges, build the dynamic characteristic theoretical analysis model ofthe2×90meter RC arch bridge and calculate the dynamic characteristics of this bridge.Based on the calculation results and combined the fundamental of the structure vibrationmeasurement, it discusses the dynamic monitoring point arrangement, excitation method andthe sample frequency setting of the2×90meter RC arch bridge which are key technologiesin dynamic load tests. It uses the NEXT/ITD method to analyze the collected randomdynamic response and recognize the bridge dynamic parameters. Exert the excitation to thebridge by means of using moving vehicle, test the speed time-history response and conductintegral operation to the speed time-history response to obtain the displacement time-historyresponse of the bridge. What’s more, it analyzes the bridge displacement coefficient. Basedon the results of dynamic parameter tests and the impact coefficient test, it analyzes andassesses the bridge dynamic properties.2. It builds the space beam grillage static force theoretical analysis model, based onwhich the static load test conditions and load location of the test load under differentworking conditions. According to the theoretical analysis results, it conducts the static loadtests to the bridge and tests the deflects and strain values of specific sections. According tothe measured data, analyze the bridge stiffness, strength and load lateral distributioncondition.3. Discuss the discriminant of RC arch bridge carrying capacity calculation, and clearthe parameter values in the discriminant. Build the theoretical analysis model to calculate theRC bridge and determine the parameters according to the region, design drawing and relatedregulations. According to the theoretical analysis model and the checking parameters, calculate the carrying capacity ultimate limit state and the serviceability limit state, based onwhich the service state of the bridge is clearly assessed.