确定混凝土软化曲线的自修正逆推法  

Self-Modifying Inverse Analysis for Determining Softening Constitutive of Concrete

作　　者：米正祥 袁任重 罗丹旎 高小峰 张洪亮[1] MI Zhengxiang;YUAN Renzhong;LUO Danni;GAO Xiaofeng;ZHANG hongliang(School of highway,Changan University,Xi'an 710064,China;Hubei communications investment Jingchu Construction Management Co.LTD,Jingzhou 434000,Hubei,China;College of Civil Engineering and Architecture,Guangxi University,Nanning 530004,China;College of Civil Engineering,Zhejiang University of Technology,Hangzhou 310023,China)

机构地区：[1]长安大学公路学院,西安710064 [2]湖北交投荆楚建设管理有限公司,湖北荆州434000 [3]广西大学土木建筑工程学院,南宁530004 [4]浙江工业大学土木工程学院,杭州310023

出　　处：《硅酸盐学报》2024年第2期641-651,共11页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(52179125);长安大学中央高校基本科研业务费专项资金资助(300102219305)。

摘　　要：为基于试验所测荷载-裂缝张开位移曲线确定出混凝土软化关系,将全局最佳拟合与参数自动修正技术相结合,提出了自修正逆推法。该方法可以考虑局部特性对软化曲线的影响,允许自定义拟合参数的搜索边界,且无需预先假定软化曲线最终形状。通过开展断裂试验,校验了所提方法的合理性、通用性与稳健性。结果表明:该方法模拟的荷载与试验结果吻合良好,逆推所得软化曲线跟拟合参数初始猜测无关,对不同形式和材料的混凝土试件普遍适用;不同湿度下的软化曲线形状相似,但湿度越低,抗拉强度和临界裂缝宽度越小,且在后期这种减小更显著。Introduction Tensile softening(σ-w) curve is a critical parameter necessary to model the non-linear fracture behavior of concrete structures by the finite element method. The uniaxial tensile test is the most direct approach to determine the softening curve, but it is a challenge due to its insufficient stiffness of the loading machine, eccentricity, asymmetric fracture modes, and multiple cracking. Alternatively, a softening curve can be derived via minimizing the deviation between the predicted and experimental results based on the load-crack mouth open displacement(F-lCMOD) curve measured by the bending or wedge-splitting tests. Inverse analysis methods are commonly used to derive σ-w curve include the J-integral, poly-linear, and global optimization. Although the J-integral method is computationally least demanding, it requires conducting the tests on two specimens with different notch sizes for deriving each σ-w curve, yielding a lower precision and a higher dispersion. For the given test data, the poly-linear method can produce a unique solution without any pre-assumptions regarding the softening curve's shape. However, it is sensitive to arbitrarily small measurement errors, yielding a softening curve with severe oscillation, and accumulating all previous errors in the current analysis step. The global optimization technique is not easy to converge when there are many fitting variables, and it needs to pre-assume the shape of the softening curve. There is no guarantee that the outputs of this technique will be globally optimal. Therefore, this paper proposed a self-modifying inverse analysis method to determine the softening curve of concrete after combining global best-fitting with an automatic correction technique. Methods The self-modifying inverse analysis method belongs to the global optimization technique with more additional constraints. This method consists of two modules, i.e., global best fitting and parameter self-modifying. The former mainly focuses on the optimum fitting of the F-lCMOD curv

关 键 词：混凝土 自修正技术 软化本构 局部特性 干–热养护 

分 类 号：TU528[建筑科学—建筑技术科学]