Study on temperature field and shear lag effect of instantaneous high temperature during paving of wide steel box beam bridge deck

Based on a single box seven chamber steel box continuous bridge, a plate element model of the bridge is established using finite element software for asphalt paving on the wide steel box girder bridge deck. The distribution of instantaneous high-temperature temperature field during asphalt paving is analyzed in detail. On this basis, the shear lag effect of paving temperature load and its influencing factors are studied. The results indicate that there are significant temperature changes in the paving layer and steel box girder during the asphalt paving process. The temperature field of the steel box girder in the paving area is significantly affected by the paving temperature. After the temperature of the steel box girder reaches 103°C, the temperature decrease rate of the flange plate is greater than that of the box chamber temperature. The temperature drop rate at the junction of the top plate, web plate, transverse partition, and flange plate is faster than in other areas. During the first 1000 seconds of paving, the temperature of the paving layer rapidly decreases, with a maximum rate of decrease reaching 21°C/min, and then the rate of temperature decrease gradually decreases. From the beginning of asphalt paving to the middle of the span, the shear lag coefficient at the edge web of the middle span gradually increases from 0.83 to 1.09. The shear lag coefficient of the middle web gradually decreased from 1.12 to 1.05, and then increased to 1.09. After asphalt paving to the mid span, the shear lag coefficients at the edge and middle web plates suddenly change to 0.64 and 0.79, respectively. Subsequently, the shear lag coefficients of the two gradually increased to 0.80 and 1.01, respectively. At the time of 3000 seconds of paving, the steel box girder experiences maximum stress. At this moment, when the temperature of the paving material is higher, the wind speed is lower, the paving thickness is greater, and the paving speed is higher, the stress in the paving area will be greater. However, under the maximum stress, the temperature of the mixture, paving thickness, and paving speed have little effect on the shear lag coefficient of the top plate in the paving area.