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为研究钢筋高强再生混凝土梁长期荷载下的变形性能,进行了6根足尺梁试件变形性能试验研究。梁截面尺寸为200 mm×300 mm,长3 300 mm,净跨3 000 mm;各梁配筋相同,纵筋配筋率1.13%,体积配箍率0.54%,纵筋净保护层厚度20 mm;混凝土为再生粗骨料混凝土,细骨料为天然砂,再生粗骨料取代率分别为0%、33%、66%、100%,再生混凝土设计强度等级为C55~C60;针对两种不同持荷水平,进行了长期荷载试验。试验中得到了荷载、梁挠度、温度、湿度随时间的变化情况。分析了不同持荷水平、不同再生粗骨料取代率梁的挠度随时间变化的规律;拟合得到了挠度-时间关系曲线及其表达式。研究表明:低持荷水平下(加载弯矩与屈服弯矩比值为0.29)高强再生混凝土梁徐变挠度比天然骨料混凝土梁的略大,挠度增大系数比高持荷水平下(加载弯矩与屈服弯矩比值为0.46、0.47)的梁挠度增大系数略大;再生粗骨料混凝土梁长期荷载下挠度增大系数可按普通混凝土梁挠度增大系数的1.1倍采用;曲线拟合及分段线性拟合得到挠度计算值与实测值吻合较好。
In order to study the deformation behavior of reinforced high-strength recycled concrete beams under long-term load, the deformation performance of six full-height beams was studied. Beam section size 200 mm × 300 mm, length 300 mm, net span 3000 mm; the same beam reinforcement, longitudinal reinforcement ratio of 1.13%, the volume of the hoop ratio of 0.54%, the longitudinal reinforcement net cover thickness of 20 mm ; Concrete is recycled coarse aggregate concrete, fine aggregate is natural sand, and the replacement rate of recycled coarse aggregate is 0%, 33%, 66% and 100% respectively; the designed strength grade of recycled concrete is C55 to C60; for two different Holding load level, a long-term load test. The load, beam deflection, temperature and humidity change with time were obtained. The law of deflection of beam with different holding load and different recycled coarse aggregate was analyzed. The deflection-time curve and its expression were obtained by fitting. The results show that the creep deflection of high strength recycled concrete beams is slightly larger than that of natural aggregate concrete beams under low load level (the ratio of load moment to yield bending moment is 0.29) The ratio of moment to yield moment is 0.46, 0.47), the deflection coefficient of beam is a little larger than that of normal concrete beam; the coefficient of deflection under long-term load of recycled coarse aggregate concrete beam can be used 1.1 times of the coefficient of deflection of ordinary concrete beam; The piecewise linear fitting shows that the calculated value of the deflection is in good agreement with the measured value.