混凝土应力损伤评价指标的敏感性分析

Sensitivity analysis of evaluation index of concrete stress damage

测试了不同预损伤程度下混凝土的立方体抗压强度、劈拉强度、弹性模量、超声波速、吸水率,对比了各评价指标的敏感性,优选出实际工程应用方便、物理力学概念清楚、可敏感反映整个损伤阈值的混凝土应力损伤评价指标。研究结果表明:应优先选择弹性模量作为混凝土应力损伤的评价指标;当试验条件和试验时间允许时,可选择吸水率作为混凝土应力损伤的评价指标,但应适当增加吸水时间的测点,以提高测试数据的可靠性;当受工程现场或试验条件限制,只能采用无损检测时,可将超声波速作为应力损伤评价指标,但需结合弹性模量或吸水率使用,不宜单独用于混凝土应力损伤的评定。

The cube compressive strength, the splitting tensile strength, the modulus of elasticity, the ultrasonic wave velocity and the water absorption of concrete under different pre-damage degrees are tested. The sensitivity of each evaluation index is compared, and the evaluation index of damage evaluation is selected, which is convenient for practical engineering application, clear in physical mechanics and sensitive to the whole damage threshold. The results show that the modulus of elasticity should be selected as the evaluation index of concrete stress damage. The water absorption rate can be selected as the evaluation index of concrete stress damage when the test conditions and the time are allowed, but the measurement point of the water absorption time should be increased properly to improve the reliability of the test data. When the engineering sites or the test conditions are limited, the ultrasonic velocity can be used as a damage evaluation index for nondestructive testing, but it is not suitable for the evaluation of concrete stress damage alone and should be used in combination with the elastic modulus or the water absorption.