Research On The Influence Of The Measurement Deviation Of The Arch Axis On The Evaluation Of The Bearing Capacity Of The Existing Arch Bridge

For the old arch bridge with missing design data,the measurement results of arch axis alignment directly affect the accuracy of the evaluation of arch bridge bearing capacity.At present,there is no scholar in China to put forward control opinions on the measurement deviation of arch axis.Based on the engineering background of a reinforced concrete arch bridge in Southwest China,with the help of MIDAS civil /designer and other finite element software,through the calculation of the arch axis coefficient and the analysis of the internal force of the main arch ring,combined with the field load test,this paper systematically studies the influence of the measurement deviation of the arch axis on the evaluation of the bearing capacity of the existing arch bridge,and draws the following conclusions,It provides reference for the inspection and evaluation of old arch bridges in the future.1.The results show that the arch axis coefficient is more affected by the decrease of the arch crown section than by the increase of the arch crown section,and the influence of the increase of the L/4 section on the arch axis coefficient is greater than that of the decrease of the L/4 section;The deviation of arch axis caused by the measurement deviation will increase the arch axis coefficient with a relatively large probability.2.The influence depth of arch axis measurement deviation on arch axis coefficient decreases with the increase of span;In the measurement of arch axis,the change of arch axis alignment caused by deviation will increase the arch axis coefficient with a relatively large probability.3.The safety factor of the bearing capacity of the arch foot section and the arch crown section has the relationship of one decrease and the other increase.Taking the structural checking calculation as the evaluation method of the bridge bearing capacity,the arch bridge needs to rely on the design safety factor.The safety factor of the arch foot determines the lower limit of the allowable range of the measurement deviation,and the safety factor of the arch crown determines the upper limit.Based on the structural inspection algorithm,considering the safety of the bridge bearing capacity,the arch axis coefficient ranges from 1.728 to 2.829,and the maximum deviation of L/4 and arch crown section can not reach 5cm at the same time.4.Based on the load efficiency coefficient and the strain and deflection values extracted from the field test,the control range of the arch axis coefficient is1.517?2.178.For the measurement of the vault elevation,the maximum allowable measurement deviation is-20?10cm,and the allowable deviation of L/4 section ±10cm,and the allowable deviation at the same time is-40?+50cm;For M-type deviation,the maximum allowable deviation is 0±5cm.