采用通用有限元程序的弥散裂缝模型和分层壳单元模拟钢筋混凝土构件裂缝宽度  

PREDICTING THE CRACK WIDTH OF REINFORCED CONCRETE STRUCTURAL MEMBERS USING THE SMEARED CRACK MODEL AND LAYERED SHELL ELEMENTS IN GENERAL-PURPOSE FINITE ELEMENT PACKAGES

作　　者：陶慕轩[1] 赵继之 TAO Mu-xuan;ZHAO Ji-zhi(Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry,Department of Civil Engineering,Tsinghua University,Beijing 100084,China;Beijing Engineering Research Center of Steel and Concrete Composite Structures,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学土木工程系土木工程安全与耐久教育部重点实验室,北京100084 [2]清华大学北京市钢与混凝土组合结构工程技术研究中心,北京100084

出　　处：《工程力学》2020年第4期165-177,共13页Engineering Mechanics

基　　金：国家重点研发计划课题项目(2017YFC0703804);国家自然科学基金项目(51722808)。

摘　　要：该文基于弥散裂缝模型,采用通用有限元程序的分层壳单元计算钢筋混凝土构件裂缝宽度的方法。讨论了理论基础,Bazant和Oh提出的经典裂缝带理论主要针对素混凝土构件,严重的局部化效应导致显著的网格依赖性,而将裂缝带理论拓展到工程常用的配筋混凝土构件时,由于多裂缝分布发展的特点,裂缝带宽应修改为平均裂缝间距而使计算结果与网格无关。在理论基础讨论的基础上,给出了采用通用有限元程序的弥散裂缝模型和分层壳单元计算钢筋混凝土构件裂缝宽度的计算流程,其中,平均裂缝间距将有限元分析中的“应变”概念和工程设计中的“裂缝宽度”概念紧密联系起来,是计算流程中最关键的参数。以某承受负弯矩的简支组合梁混凝土板开裂分析为例,验证并讨论了网格相关性、大软化模量导致数值收敛困难的应对策略、平均裂缝间距的决定性作用等重要问题。This study investigated the method for calculating the crack width of reinforced concrete structural members using layered shell elements in general-purpose finite element packages.The calculation was based on the smeared crack model.The theoretical background was discussed first.The classical crack band theory proposed by Bazant and Oh is only suitable for plain concrete structural members,with significant localization effect resulting in possible mesh dependency.When the crack band theory is extended to reinforced concrete structural members that are commonly used in engineering practices,considering the characteristics of distributed multi-crack pattern,the crack band width should be modified as the average crack spacing so that the calculation results are independent of the element mesh.Based on the theoretical background,a calculation procedure for calculating the crack width of reinforced concrete structural members using the smeared crack model and layered shell elements in general-purpose finite element packages was proposed.In this procedure,the average crack spacing is the most critical parameter that closely relates the strain concept in the finite element analysis with the crack width concept in engineering design.Finally,the cracking behavior of a concrete slab in a simply supported composite beam subjected to a negative moment was analyzed as an example.Critical issues including the mesh sensitivity,solutions to the numerical convergence difficulty caused by large softening modulus,and the dominant role of the average crack spacing etc.were verified and discussed.

关 键 词：裂缝带理论 开裂 平均裂缝间距 有限元方法 分层壳单元 裂缝宽度 网格相关性 

分 类 号：TV332[水利工程—水工结构工程] TU528[建筑科学—建筑技术科学]