Abstract
A model test and finite element analysis were conducted in this study to determine the distribution law of shear lag effect in the main beam section, a box girder, during the cable‐stayed bridge construction process. The experimental and theoretical results were compared in an example of loading the control section. The stress value of the cable tension area of the main beam upper edge was found to markedly change when tensiling the cable force and was accompanied by prominent shear lag effect. After a hanging basket load was applied, the main beam of certain sections showed alternating positive and negative shear lag characteristics. The shear lag distribution law in the box girder of the single‐cable‐plane prestressed concrete cable‐stayed bridge along the longitudinal direction was determined in order to observe the stress distribution of the girder. The results show that finite element analysis of the plane bar system should be conducted at different positions in the bridge under construction; the calculated shear lag coefficient of the cable force acting at the cable end of the cantilever reflects the actual force. In the beam segments between the cable forces, the shear lag coefficient determined by the ratio of the bending moment to the axial force reflects the actual stress at the cable force action point. In the midspan beam section between the action points of cable forces, the shear lag coefficient of the bending moment reflects the actual stress. The section shear lag coefficient can be obtained by linear interpolation of the beam section between the cable action point and the middle of the span.
Highlights
A model test and finite element analysis were conducted in this study to determine the distribution law of shear lag effect in the main beam section, a box girder, during the cable-stayed bridge construction process. e experimental and theoretical results were compared in an example of loading the control section. e stress value of the cable tension area of the main beam upper edge was found to markedly change when tensiling the cable force and was accompanied by prominent shear lag effect
After a hanging basket load was applied, the main beam of certain sections showed alternating positive and negative shear lag characteristics. e shear lag distribution law in the box girder of the single-cable-plane prestressed concrete cable-stayed bridge along the longitudinal direction was determined in order to observe the stress distribution of the girder. e results show that finite element analysis of the plane bar system should be conducted at different positions in the bridge under construction; the calculated shear lag coefficient of the cable force acting at the cable end of the cantilever reflects the actual force
In the cable-stayed bridge discussed here, the beam segment is in a cantilever state during the construction process. e box girder shear lag coefficient fluctuates as the stay cable is placed continuously under tension; the shear lag effect becomes increasingly prominent as construction progresses so that the distribution law of shear lag effect on the main beam of a single-cable-plane cable-stayed bridge during construction was systematically analyzed in this study. e model test and numerical analysis results were used to analyze the distribution of shear lag in the transverse direction of the main beam section
Summary
E stay cable, box girder, and main tower were gradually compensated for dead loads and the stay cable was tensioned and adjusted as necessary. E model test was carried out to simulate the construction load and stress of the girder section under the working conditions of a midspan closure in the construction stage. In Working Condition 1 (double cantilever stage), we installed 1 (1′) beam section, tensioned C1–C4 (C1′-C4′) cables, and applied a hanging basket load. In Working Condition 2 (maximum double cantilever stage), we installed 2 (2′) and 3 (3′) beam sections, tensioned C5–C10 (C5′-C10′) cables, and applied a hanging basket load. In Working Condition 4 (maximum single cantilever stage), we installed Section 4, tensioned C12–C14 (C12′-C14′) cables, and applied a hanging basket load at the C14 cable. Working Condition 6 included cable tension adjustment and application of a second-stage dead load
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