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通过对再生粗骨料取代率0%、30%、50%、80%、100%的再生混凝土梁进行短期以及对其中取代率0%、50%、100%再生混凝土梁1 200 d的长期变形试验研究,对比分析普通混凝土梁与再生混凝土梁、不同取代率再生混凝土梁之间变形发展规律。研究结果表明:再生混凝土梁短期刚度较普通混凝土梁小,长期加载阶段再生混凝土较普通混凝土、高取代率较低取代率再生混凝土梁呈现出变形前期增长缓慢、后期增长加速、长期变形曲线收敛时间较长的“后延性”特点;同时以短期变形试验数据为基础,拟合内力臂系数、钢筋应变不均匀系数、截面弹塑性抵抗矩系数,提出再生混凝土梁短期刚度计算方法;基于长期附加变形数据,提出挠度增大影响系数并建立适用于不同取代率再生混凝土梁长期刚度计算公式,采用该公式的计算结果与本试验及国内其他学者试验结果吻合较好,满足计算精度要求。
The short-term and long-term deformation of 1 200 d concrete with 0%, 50%, 100% replacement of recycled raw concrete beams were studied by replacing recycled concrete beams with recycled coarse aggregate of 0%, 30%, 50%, 80% and 100% Experimental study is carried out to compare and analyze the regularity of deformation between ordinary concrete beams and recycled concrete beams and different replacement ratios of recycled concrete beams. The results show that the short-term stiffness of recycled concrete beams is smaller than that of ordinary concrete beams, and the recycled concrete beams of long-term loading stage are lower than those of ordinary concrete. The low replacement rate of recycled concrete beams shows slow growth in early deformation stage, Long-term “ductility” characteristics. At the same time, based on the short-term deformation test data, the calculation method of short-term stiffness of recycled concrete beams is put forward based on the fitting of the internal force arm coefficient, the steel strain nonuniformity coefficient and the section elastic- Additional deformation data are proposed to increase the influence coefficient of deflection and to establish the formula for long-term stiffness of recycled concrete beams with different substitution rates. The calculation results of this formula are in good agreement with the test results of other domestic scholars to meet the calculation requirements.