硫酸盐侵蚀下超高性能混凝土连接预制梁受弯性能研究

Study on the Bending Performance of Precast Beams with Ultra-High Performance Concrete Joints under Sulfate Erosion

摘要: 为了研究5%硫酸盐浸泡不同时间段的超高性能混凝土连接预制梁力学性能，设计并制作了五根超高性能混凝土预制梁。通过抗弯性能试验，研究了浸泡不同时间硫酸盐溶液(0天，30天，60天，180天，390天)对于预制梁抗弯性能的影响。实验结果表明：浸泡过后预制梁与未浸泡的弯曲破坏形式相似，裂缝均出现了从支座处向受压区开展的趋向，随着硫酸盐浸泡时间的增加，破坏状态下的最大裂缝宽度呈现先降低后增大，随着硫酸盐浸泡时间的大跨度增大，试验梁裂缝开展的更为迅速，且前期裂缝增大变化更为明显。其整体刚度先增大后降低，试验梁均符合平截面假定，经过混凝土本构模型的建立，其压缩(拉伸)应力–应变曲线在腐蚀时间0~60天范围内呈现上升趋势，而之后出现整体下降的趋势，且侵蚀时间越长下降程度越来越大，下降的速度成倍增加，ABAQUS有限元数值模拟结果与试验结果吻合程度较高。

Abstract: In order to study the mechanical properties of ultra-high performance concrete joint precast beams immersed in 5% sulfate for different time periods, five ultra-high performance concrete precast beams were designed and fabricated. The effects of immersing sulfate solution for different time periods (0 Day, 30 Days, 60 Days, 180 Days, 390 Days) on the flexural properties of precast beams were investigated by flexural performance tests. The experimental results show that: after immersed precast beams and unimmersed bending damage form is similar, cracks have appeared from the support to the compression zone to carry out the tendency, with the increase of the sulfate immersion time, the maximum width of cracks in the damage state shows first decrease and then increase, with the sulfate immersion time of the span increase, the test beams cracks to carry out more quickly, and the early cracks to increase the change is more obvious. Its overall stiffness increases and then decreases, the test beams are in line with the flat cross-section assumption, after the establishment of the concrete constitutive model, its compressive (tensile) stress-strain curve in the range of corrosion time 0~60 d shows a rising trend, and after that there is an overall downward trend, and the longer the erosion time decreases the degree of decreasing is more and more, and the rate of decreasing increases exponentially. ABAQUS finite element numerical simulation results are in good agreement with test results.