Abstract
Steel bottom plates are applied as replacements for the concrete bottom plates in order to reduce the dead weight of the composite box girders with corrugated steel webs and steel bottom plates (CSWSB). Due to the change in the material, the previous analytical calculation methods of vertical deflection of composite box girders with corrugated steel webs (CSWs) cannot be directly applied to the improved composite box girders. The shear lag warpage displacement function was derived based on the shear deformation laws of the upper flange and the bottom plates of the improved composite box girders. The equations for the calculation of the shear deformation and the additional deflection due to the shear lag of continuous and simply supported composite box girders with CSWSB under concentrated and uniformly distribution loads were derived by considering the double effects of the shear lag and the shear deformations of the top and the bottom plates with different elastic moduli. The analytical solutions of the vertical deflection of the improved composite box girders include the theory of the bending deflection of elementary beams, shear deformation of CSWs, and the additional deflection caused by the shear lag. Based on the theoretical derivation, an analytical solution method was established and the obtained vertical deflection analytical solutions were compared with the finite element method (FEM) calculation results and the experimental values. The analytical equations of vertical deflection under the two supporting conditions and the two load cases have verified the analyses and the comparisons. Further, the additional deflections due to the shear lag and the shear deformation are found to be less than 2% and 34% of the total deflection values, respectively. Moreover, under uniform distributed load conditions, the deflection value was found to be higher than that of the under concentrated load condition. It was also found that the ratio of the deflection caused by the shear lag or the shear deformation to the total deflection decreased gradually with the increase in the span width ratio. When the value of the span width ratio of a single box and single chamber composite box girder with CSWSB was equal to or greater than 8, the deflections caused by the shear lag and the shear deformation could be ignored.
Highlights
Steel bottom plates are applied as replacements for the concrete bottom plates in order to reduce the dead weight of the composite box girders with corrugated steel webs and steel bottom plates (CSWSB)
When the value of the span width ratio of a single box and single chamber composite box girder with CSWSB was equal to or greater than 8, the deflections caused by the shear lag and the shear deformation could be ignored
The following conclusions were obtained: (1) e deflections that were caused by the shear lag and the shear deformation of the supported and continuous composite box girders with CSWSB under different loading conditions were calculated theoretically and were found to be in good agreement with the measured values of the model test and the ANSYS finite element values, verifying the correctness of the deflection calculation equations
Summary
Received 30 December 2020; Revised 11 March 2021; Accepted 17 March 2021; Published 30 March 2021. The deflection calculation equations due to the shear lag and the shear deformation of the continuous and supported composite box girders with CSWSB under different loads were obtained. (2) e deflection caused by the shear lag effect of the continuous composite box girders with CSWSB under the concentrated loads w21 and w22 was obtained as shown in the following equations:. (2) Deflection due to the shear lag effect of continuous composite box girders with CSWSB under uniformly distributed load w2 is obtained as shown in the following equation: w2. (3) Deflection due to the shear deformation of continuous composite box girders with CSWSB under uniformly distributed load w3 is obtained as shown in the following equation: w3. CSWSB under concentrated load were obtained as shown in the following equations: x≤
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