逆推混凝土软化曲线及其断裂能的研究  

Research on softening curve of concrete and fracture energy by inverse analysis

作　　者：赵志方[1] 李铭[1] 赵志刚[2] 

机构地区：[1]浙江工业大学建筑工程学院,浙江杭州310014 [2]浙江传媒学院电子信息学院,浙江杭州310018

出　　处：《混凝土》2010年第7期4-7,共4页Concrete

基　　金：国家自然科学基金(50409005);浙江省自然科学基金(Y106486);浙江省自然科学基金(Y1090151);交通部西部交通建设科技项目(2008-318-223-43)

摘　　要：断裂能是描述混凝土受拉开裂的重要参数。混凝土的断裂能可通过RILEM推荐的断裂功的方法确定,还可通过拉伸软化曲线下的面积确定。基于虚拟裂纹模型并采用Levenberg-Marquardt优化算法,由三点弯曲切口梁断裂试验获得的(荷载-裂缝口张开位移)曲线做逆分析,获得混凝土的软化曲线。在位移控制加载的试验机上完成6组不同尺寸的三点弯曲梁的稳定断裂试验。与单轴直接拉伸试验相比,逆推法获得的混凝土软化曲线试验具有容易实现和试验成功率高的优点。两种方法获得的混凝土断裂能变化趋势相同,随试件尺寸增大而增大,到达一定试件尺寸,断裂能不再增大。研究结果还表明,逆推获得的软化曲线具有尺寸效应,可用来解释断裂能的尺寸效应。Fracture energy,an important parameter which can characterize concrete cracking,can be obtained by a method recommended by RILEM.Meanwhile,it can also be got by the area under the softening curve.Based on the Levenberg-Marquardt optimization algorithm and TPB test data,softening curves were obtained by inverse analysis by fitting the calculated P-CMOD curves to the tested P-CMOD curves.Six groups of the TPB beams were tested and the stable fracture tests were obtained under displacement-controlled loading.Compared with uniaxial tension test,TPB test is much easier to carried out and it＇s success ratio is much higher.It is found that the fracture energy by the two methods show the same trend,namely,fracture energy increases with growth of specimen size and tends to increase no longer when the specimen size attains to a certain level.The result also shows that the size effect of softening curve may explain the size effect of fracture energy.

关 键 词：混凝土 逆分析 LEVENBERG-MARQUARDT算法 软化曲线 断裂能 尺寸效应 

分 类 号：TU528.01[建筑科学—建筑技术科学]