混凝土连续箱梁长期受力性能分析

LONG-TERM BEHAVIOR ANALYSIS OF CONCRETE CONTINUOUS BOX GIRDER

以钢筋混凝土连续箱梁1006d的长期受力性能试验为基础,考虑混凝土收缩徐变和弹性支座不均匀沉降影响,采用徐变换算截面法分析了连续箱梁的结构内力重分布、截面应变应力重分布和长期挠曲变形,并与实测结果进行对比分析。研究表明:持续荷载作用引起受拉钢筋的应变增长相对较小,且跨中截面的拉应变增长较中间支座截面显著。持续荷载作用引起受压钢筋和受压混凝土的应变增长相对较大,且跨中截面的压应变增长较中间支座截面显著。持荷1006d边支座反力系数理论值较初始值增长7.0%,边支座反力系数实测值较初始值增长7.2%,理论值与实测结果吻合较好;连续箱梁结构内力重分布效应对其长期挠曲变形的影响较大。

This paper investigates the structure internal force redistribution, the sectional strain and stress redistribution and long-term flexural deformation of reinforced concrete continuous box girders. To do that, 1006 days＇ long-term behavior test is carried out, and concrete shrinkage, creep and uneven settlement of elastic supports are considered by means of creep transformed-section method. It is shown that： 1） the strain of tensile steel bars increases slightly, especially at the mid-support section; 2） the compressional strains of steel bars and concrete increase relatively larger under sustained loading, especially at the mid-span section; 3） the theoretical reactions at the side-support increase 7.0% after 1006 days loading, while the measured reactions increase 7.2%; 4） the structure internal force redistribution has great influence on long-term flexure deformation of continuous box girders.