高强钢筋混凝土连续梁弯矩调幅研究

将高强钢筋作为受拉纵筋时，由于钢筋屈服强度的提高，连续梁支座控制截面从受拉边缘混凝土进入受拉塑性至受拉纵筋屈服的区段变长，这一阶段弯矩调幅幅度在总弯矩调幅中所占比例增大；支座控制截面塑性铰出现推迟，截面相对受压区高度相同时塑性铰转动能力减小。为此，提出了将高强钢筋混凝土连续梁弯矩调幅分受拉纵筋屈服前、后两阶段。对以受拉纵筋屈服强度、中支座控制截面相对受压区高度、中支座支承宽度、跨高比、加载形式为控制变量的336根两跨连续梁进行参数化分析。结果表明：随着钢筋屈服强度的提高，第一阶段弯矩调幅增大、第二阶段弯矩调幅减小；随着中支座控制截面相对受压区高度增加，两阶段弯矩调幅均减小；随着中支座支承宽度的增加，第一阶段弯矩调幅增大、第二阶段弯矩调幅变化不显著；随着跨高比的增大，第一阶段弯矩调幅减小、第二阶段弯矩调幅变化不显著。建立了不同加载形式下考虑上述各参数影响的两阶段连续梁弯矩调幅系数计算公式。

Study on moment redistribution in continuous concrete beams with high-strength steel bars

For the continuous concrete beams with high-strength steel bars as tensile reinforcement, the process from the tensile concrete turning into the plasticity to the steel bars yielding becomes longer due to the increase of the yield strength of the steel bars. In this stage, the proportion of the moment redistribution to the total moment redistribution increases. The plastic hinge appears to be delayed and the plastic hinge rotation capacity decreases when the relative depth of the compression zone is constant. Based on this, the moment redistribution in continuous beams with high-strength steel bars was divided into two stages according to whether the steel bars has yielded or not. 336 continuous beams were parametrically analyzed with the relative depth of the compression zone, yield strength of the steel bars, span-to-depth ratio, loading forms and width of the mid-support as control variables. The results indicate that, the first-stage moment redistribution is increased and the second-stage moment redistribution is decreased with the increase in the yield strength of reinforcement. The two-stage moment redistribution is decreased with the relative depth of compression zone increasing. The first-stage moment redistribution is increased as the width of mid-support increases and the span-to-depth ratio decreases. And the variation of the second-stage moment distribution is not significant with the width of mid-support and the span-to-depth ratio. Formulas of the two-stage moment redistribution in continuous beams with different loading forms are proposed considering the effects of the above-mentioned parameters.