三点弯曲下混凝土断裂性能参数试验研究  

Experimental Study on Fracture Properties of Concrete Based on Three Point Bending Tests

作　　者：刘春[1] 陈红鸟[1] 赵艳兵[1] 孙敬明 才琪[1] 

机构地区：[1]贵州大学空间结构研究中心,贵阳550003

出　　处：《硅酸盐通报》2016年第12期4191-4200,4211,共11页Bulletin of the Chinese Ceramic Society

基　　金：国家自然科学基金(51408144);贵州大学人才引进基金项目(201301);贵州大学研究生创新基金(2016001)

摘　　要：采用三点弯曲试验对混凝土断裂性能参数进行研究,测试了一系列尺寸相同、强度不同的预制切口梁。通过采用等效裂缝模型和双参数模型确定混凝土的断裂韧度,结果表明:采用等效裂缝模型和双参数模型计算的混凝土断裂参数基本相同;随着抗压强度的增加,断裂韧度呈上升趋势,通过曲线拟合,提出根据抗压强度确定断裂韧度的经验公式。通过对试验荷载-挠度曲线进行三种不同的处理,包括国际材料和结构实验室联合会(RILEM)建议、对曲线尾部进行延伸以及采用实际的曲线,得到基于虚拟裂缝模型的断裂能。结果表明,RILEM建议得到的断裂能偏大,当曲线下降段的最低荷载与峰值荷载比值P_(min)/P_c0.04时,采用实际荷载-挠度曲线得到的断裂能与尾部延伸后曲线得到的断裂能误差小于5%,可为实际断裂试验的实施提供参考。A series of pre-notched concrete beams with the same geometric sizes and different compressive strengths were tested by using three point bending tests to investigate the fracture properties of plain concrete. The fracture toughness of concrete was determined by using the Equivalent Fracture Model and the Two Parameter Fracture Model. Analytical results indicated that the fracture parameters determined by these two models were close. The fracture toughness increased as the increase of compressive strength of concrete. Empirical formula was built to determine the fracture toughness by using the compressive strength. The fracture energies were determined from the experimental load-deflection curves via three means, including the proposals recommended by RILEM, tail extension of the curves by curve fitting and the actual curves. The results showed that fracture energies obtained by RILEM recommendation were higher than that obtained by the other two methods. Wherr the ratio of the lowest load at the descending part of the curve to the peak load （ Pmin/Pc ） was lower than 0.04, the errors of the fracture energies obtained by the actual load-deflection curves and that obtained by the extended curve were less than 5%, which could provide a reference for the implementation of the fracture tests.

关 键 词：三点弯曲 素混凝土 抗压强度 断裂韧度 断裂能 

分 类 号：TU528.01[建筑科学—建筑技术科学]