摘要
在地震多发地,混凝土结构常常承受循环荷载作用,为了研究循环加卸载作用下再生混凝土的受压损伤特性,对不同再生粗骨料取代率的混凝土试件进行单轴抗压试验。基于声发射技术,对受压损伤全过程进行了动态分析。研究表明:循环荷载作用下,再生混凝土声发射振铃计数存在Kaiser效应,该效应反映了材料损伤程度,同时揭示了不同掺量再生混凝土的损伤机制;随着应力水平的增加,Felicity比逐渐减小,以Felicity比小于1作为混凝土损伤严重的标志;将每次循环声发射振铃图进行分形计算,循环荷载作用下再生混凝土声发射振铃分形维数随着循环次数的增加而增加,证明了声发射应用于损伤预测的可行性;应用响应比理论对声发射累计事件的研究得出:再生混凝土加卸载声发射数响应比Y随着试件承受的应力水平的增高而减小,且将Y减小至1左右时作为再生混凝土破坏前兆特征,为工程损伤预测及安全评估提供参考。
In earthquake-prone areas,concrete structures are often subjected to cyclic loads.In order to study the compression damage characteristics of recycled aggregate concrete under cyclic loading and unloading,uniaxial compression tests were carried out on concrete specimens with diffe-rent replacement rates of recycled coarse aggregate.Based on acoustics emission(AE)technology,dynamic analysis was made on the damage characteristics of recycled aggregate concrete during the whole process.The results show that:Kaiser effect exists in the acoustic emission ring count of recycled aggregate concrete under cyclic loading,which not only reflects the damage degree of materials,but also reveals the damage mechanism of recycled concrete with different replacement rate,with the increase of stress level,Felicity ratio decrease,Felicity ratio<1 as a sign of serious damage of concrete;the fractal analysis of each cyclic AE ringing diagram shows that the fractal dimension of recycled concrete AE ringing increases with the increase of the number of cycles under cyclic loading,which proves the feasibility of applying AE in damage prediction.Based on the study of cumulative AE events by using the response ratio theory,it is concluded that AE response ratio Y decreases with the increase of the stress level of the specimen under regenerated concrete loading and unloading,and when the response ratio Y decreases to about 1,it can be regarded as a precursor to the failure of regenerated concrete,providing a reference for engineering damage prediction and safety assessment.
作者
于江
皮滟杰
秦拥军
YU Jiang;PI Yanjie;QIN Yongjun(College of Civil Construction,Xinjiang University,Urumqi 830047,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2021年第13期13011-13017,共7页
Materials Reports
基金
国家自然科学基金(51668060)。
关键词
再生混凝土
循环加卸载
声发射
KAISER效应
分形维数
响应比
recycled aggregate concrete
cyclic loading and unloading
acoustics emission(AE)
Kaiser effect
fractal dimension
response ratio
