荷载-盐渍土环境耦合下纤维混凝土柱受剪性能

Shear Performance of Fiber Reinforced Concrete Columns under Load and Saline Soil Coupling Environment

为研究盐渍土侵蚀后混凝土柱的受剪性能,对11个聚丙烯纤维锂渣混凝土柱施加不同的预加荷载并进行龄期分别为0 d、90 d、180 d的盐渍土环境侵蚀试验,对历经侵蚀后的试件进行低周水平反复荷载试验,分析侵蚀时长、轴压比和预加荷载等因素对纤维锂渣混凝土柱抗剪性能变化规律及其破坏机理.结果表明,聚丙烯纤维和锂渣的加入能提高混凝土柱在盐渍土环境下的抗剪性能;轴压比相同时,随着侵蚀时间的延长,纤维混凝土柱的受剪承载力呈先上升后下降的趋势;随着预加荷载作用的提高,柱的受剪承载力先提高后降低;当侵蚀时间一定时,将轴压比从0.2提高到0.3,侵蚀后构件受剪承载力随轴压比增大而增大.根据试验结果,基于修正压力场理论和变角桁架-拱模型理论,将纤维作用视为拉力场并与箍筋共同进行力学分析,建立盐渍土预加荷载作用下聚丙烯纤维混凝土柱的受剪承载力计算公式,理论计算值与试验值之比的平均值为0.970,标准差为0.086,变异系数为0.090,二者吻合较好.

To study the shear performance of concrete columns corroded by saline soil,apply different preloads to 11 polypropylene fiber lithium slag concrete columns and saline soil environmental erosion tests were carried out at the ages of 0 days,90 days and 180 days.Then the specimens after erosion were subjected to low cycle level repeated loading tests.The influence of erosion time,axial pressure ratio,and preloads on the shear resistance of fiber lithium slag concrete columns and their failure mechanism were analyzed.The results show that the addition of polypropylene fiber and lithium slag can improve the shear resistance of concrete in saline soil environment;at the same axial compression ratio,with the increase of erosion time,the shear capacity of fiber-reinforced concrete columns shows a trend of first increasing and then decreasing;with the increase of the preloads,the shear capacity of the column increases first and then decreases.When the erosion time is fixed,the shear capacity of eroded members increases after setting the axial compression ratio from 0.2 to 0.3.According to the experimental results,and considering the influence of the fiber on the shear bearing capacity,a formula for calculating the shear bearing capacity of fiber columns is established based on the truss arch model,the fiber effect is considered as a tension field and is analyzed together with the stirrup.The average value of the ratio between the theoretical calculation value and the test value is 0.970,the standard deviation is 0.086,and the coefficient of variation is 0.090.Both two are better matched.