Analysis of the Impact of Storage Duration on Camber and Static Load Test Results of Precast Box Girders
In order to avoid the excessive camber of the precast concrete box girder during the storage period and improve the reliability of the static load test results,this study investigated the influence of the storage duration on the camber and static load test results by taking a 25-meters box girder as representative.In terms of the influence analysis of the camber,the effects of the storage duration and the development of concrete strength on the camber were analyzed by numerical analysis and experimental verification.In terms of the influence analysis of the static load test results,the static load test was carried out on the 6 pieces of concrete precast box girders with a storage duration of 20 to 70 days,and the effects of the storage duration on the deflection,strain calibration coefficient,relative residual deformation and neutral axis height were compared and analyzed.The results showed that the measured value of the camber was about 80%of the calculated value,and the influence of concrete strength development on the camber was less than 6%.The calibration coefficient of deflection and strain decreased with the increase in storage duration,and the reduction of the calibration coefficient caused by the difference of the storage duration of 50 days was about 0.14.The relative residual deformation and the height of the neutral axis first decreased and then increased with the increase in storage duration,with a time inflection point of 40 days.
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