高温后灌浆料静动态单轴受压力学性能

灌浆料是套筒灌浆连接的关键组成部分。通过36个试件的单轴受压试验,设置静、动态加载应变率,研究高温后灌浆料的力学性能。结果表明：预烘干(105 ℃、120min)结合升温速率5 ℃/min的复合措施抑制了灌浆料(抗压强度85.7MPa)的爆裂；灌浆料试件的失效模式为竖向通缝式开裂；动态加载应变率(0.067s-1)下的高温后试件峰值应力普遍高于静态下的值,最高可达29.6%；高温后灌浆料应力-应变归一化曲线包括上升、下降两部分,二者均呈现非线性发展特征；通过试验数据的拟合分析,建立高温后灌浆料单轴受压归一化静动态本构模型,并将其应用于高温后套筒灌浆连接高应力反复拉压的有限元模拟分析,率先实现模拟对象的套筒外钢筋断裂,且模拟对象的荷载-位移曲线、峰值荷载等特征与实测结果吻合度较高,并得到400℃为高温作用后套筒灌浆连接失效模式转变的临界温度。

Static and Dynamic Mechanical Behaviors of Heat-damaged Cementitious Grout Under Uniaxial Compression Loadings

Cementitious grout is the crucial part of the grouted sleeve connection. A uniaxial compression test with 36 specimens was exerted to study the mechanical behaviors of heat-damaged cementitious grout under static or dynamic loading strain rates. It was found that explosive spalling was inhibited by the combined measures of pre-drying temperature with 105 oC in 120min and the heating rate with 5 oC/min. There were other findings after the specimens being loaded as follows: all specimens were failed to several vertical fractures with full-length along the height; the compressive strength of heat-damaged specimens under dynamic loading strain rate with 0.067 s-1 were higher than these under static loading, which was up to 29.6%; the normalized curves between stress and strain of heat-damaged specimens contained ascending and declining segments, both of which were nonlinear curves; based on the experimental data, a combined static and dynamic uniaxial compression model of heat-damaged cementitious grout was built and used for finite element simulation of heat-damaged grouted sleeve connections under high stress cyclic loading; peak loads and load-displacement curves from the simulation were consistent with the test results. In addition, the failure pattern of heat-damaged grouted sleeve connections under high stress cyclic loading with rebar fracture outside the sleeve was firstly demonstrated in the simulation, and converted into the bond slip failure between cementitious grout and rebar after the connections were exposed to elevated temperatures beyond 400 oC.