约束圆环试验混凝土裂缝扩展全过程研究  

Concrete Crack Initiation and Propagation Process in the Restrained Shrinkage Ring Test

作　　者：罗昊[1] 荣华 袁文岩 董伟[1] 

机构地区：[1]大连理工大学海岸和近海工程国家重点实验室,辽宁大连116024 [2]中冶建筑研究总院,北京100000

出　　处：《水利与建筑工程学报》2016年第4期168-172,共5页Journal of Water Resources and Architectural Engineering

基　　金：国家自然科学基金项目(51478083;51109026)

摘　　要：美国国家公路与运输协会(AASHTO)及美国试验材料学会(ASTM)推荐约束圆环试验为评估早期混凝土抗裂性的标准试验方法。为了更好地研究约束圆环试验中混凝土的破坏机理,利用ANSYS有限元软件热学分析和结构分析模块,在混凝土上施加虚拟温度场来模拟收缩作用。结合应力分析结果确定混凝土的起裂位置,并引入虚拟裂缝模型,模拟外圆周干燥的圆环试件收缩裂缝在起裂后的扩展过程。通过对比混凝土开裂时间,预测结果和试验结果吻合良好,验证了数值模拟中提出的计算方法的可行性。结果显示,在约束圆环试验中,限制收缩裂缝形成后直接进入失稳扩展阶段,试验中钢环压应变的突然滞回反映了混凝土限制收缩条件下的失稳扩展。The restrained ring test recommended by AASHTO and ASTM has been used for assessing the crack resistance of early-age concrete. In order to investigate the fracture mechanics of concrete in the ring test,shrinkage was simulated through applying the fictitious temperature filed on concrete based on thermal and structural analysis module in ANSYS. Combining with the stress analysis results,the crack location of concrete ring was determined,combining with the fictitious crack model,the crack propagation after initiation of ring specimens with circumference exposed was simulated. At the same time,the proposed method is proved feasible because concrete cracking time from numerical results and experimental results agree well. It was found that concrete directly go into unstable propagation stage after crack initiation in the restrained circular ring test,and the sudden drop of steel compressive strain represents onset of crack unstable propagation.

关 键 词：约束收缩 破坏机理 虚拟裂缝模型 裂缝扩展 

分 类 号：TU528.1[建筑科学—建筑技术科学]