| In the past,the study of large tonnage box girder carrier is mainly in the line straight section or large radius curve section,and the radius of the carrier curve is basically more than 2000m,and mainly concentrated in the field of carrier technology,construction technology and carrier equipment.However,there are few studies on the stress of the pressure box girder in the process of large tonnage box girder carrier in the small radius curve section of the highway.Based on the background of Hangzhou-Ningbo high-speed double-track project,this paper adopts the methods of field test and ABAQUS finite element simulation to do the following research on the moving frame of small radius curve section of 50m/1650t large tonnage precast box girder:(1)The analysis shows that the key technologies of this project are as follows:beam transporters and bridge erectors need to adapt to the small curve section of R 1800m and the transverse slope of 4%bridge deck respectively.Through the preliminary stress analysis of the carrier condition,it is concluded that the unfavorable working conditions of the beam are:the front vehicle center drives to the mid-span of the pressure box girder,the front wheel of the front vehicle is about to exit and the rear vehicle center drives to the mid-span of the pressure box girder;the unfavorable working conditions of the simple support are as follows:the beam carrier is fed in place at one time,the front and rear lifting trolley runs to the lifting beam position,the front and rear lifting trolley synchronizes the lifting box to the high position,the waiting box girder is longitudinally moved to the middle leg and the waiting box girder is transversely moved in place.(2)According to the experimental test and ABAQUS finite element model calculation,generally speaking,the longitudinal stress of the mid-span box girder is slightly larger than that of the side-span box girder,whether it is transported on the beam or simply supported.The most unfavorable conditions of longitudinal and transverse stress on the upper beam are:the center of the front car or the rear car drives to the middle of the bearing box girder,and the most unfavorable conditions of longitudinal and transverse stress on the simply supported erection are:the beam carrier once feeds the beam in place,and the box girder to be erected moves transversely in place.By comparing the measured values with the theoretical values,the validity of the finite element model is verified.Through the overall stress analysis of the carriage,it is concluded that its strength and deformation meet the requirementsunder the most unfavorable conditions.(3)The influence of different supports on the stress of diaphragm in the discontinuous end of side-span pressure-bearing box girder during the transportation and erection was simulated.The results show that the discontinuous end of side-span pressure-bearing box girder should not be supported only by temporary supports,but by only permanent supports,and both temporary supports and permanent supports.(4)The influence of the non-uniform deformation of the discontinuous end of the side span bearing box girder on the force of the diaphragm is simulated.The results show that the box girder structure is sensitive to the non-uniform deformation.When the beam is transported on the beam,the non-uniform deformation range of the box girder at the high side and low side permanent supports of the discontinuous end of the side span pressure-bearing box girder should not exceed 2mm and 2.5mm,respectively.When the simple support is set up,the uneven deformation range of the box girder at the high side and low side permanent supports of the side span bearing box girder should not exceed 2mm;since the large tensile stress is mainly concentrated at the four chamfers of the manhole,it is recommended to strengthen the arrangement of 45° oblique reinforcement at the four chamfers of the manhole.(5)The influence of the offset load of the beam carrier on the structure of the pressure box girder in the R1800m small radius curve section is simulated.The results show that whether the beam carrier moves to the high side or to the low side of the medium-span pressure box girder,with the increase of the offset distance,the stress and deflection are increasing.In terms of the strength and deformation of the medium-span compression box girder,the safety red line range of the beam transport vehicle is within 1400mm offset to the high side or low side.When the beam transport vehicle turns on the beam,some wheel of the beam transport vehicle also meets the requirements when it is rolled at the root of the flange plate. |
