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对9根不同再生骨料取代率的再生混凝土梁试件进行了常温和标准升温条件下的受剪试验,研究再生粗骨料取代率和初始荷载比等对试件的破坏特征、耐火极限、温度场分布和变形性能等的影响。利用ABAQUS有限元分析软件分别进行试件的温度场分析和顺序热-应力耦合全过程分析,并提出高温下再生混凝土梁受剪承载力理论计算方法和设计计算式。研究结果表明:高温下再生混凝土梁的剪切破坏特征与普通混凝土梁相似,但再生骨料取代率越大,火灾试验后试件表面混凝土的剥落程度越明显;试件的耐火极限随再生粗骨料取代率的增大而提高,随初始荷载比的增大而降低,再生混凝土梁的耐火极限受初始荷载比的影响比普通混凝土梁低;再生粗骨料取代率越大,相同时刻试件内部测点的温度越低,箍筋温度也越低,再生混凝土梁比普通混凝土梁具有更好的耐火性能;在火灾试验末期,随着再生粗骨料取代率的增加,试件的变形增长速率逐渐减小,说明高温下再生混凝土梁斜截面破坏时的延性比普通混凝土梁好;有限元分析结果与试验结果吻合较好;提出的高温下再生混凝土梁受剪承载力理论计算方法和设计计算式均具有可行性,能够分别满足试验和工程设计的要求。
The shear tests of 9 recycled concrete beams with different replacement ratios of recycled aggregates under normal temperature and standard temperature were carried out to study the failure characteristics of the recycled concrete specimens such as the replacement ratio and initial load ratio of recycled coarse aggregate, Temperature field distribution and deformation properties. The ABAQUS finite element analysis software was used to analyze the temperature field of the specimen and the whole process of sequential thermal-stress coupling. The theoretical calculation method and design formula of the shear capacity of the recycled concrete beam under high temperature were proposed. The results show that the shear failure characteristics of recycled concrete beam are similar to that of ordinary concrete beam at high temperature, but the greater the replacement rate of recycled aggregate is, the more obvious the spalling of concrete on the surface of specimen after fire test. Aggregate substitution rate increases and increases with the initial load ratio decreases, the fire resistance of recycled concrete beams by the initial load ratio lower than ordinary concrete beams; recycled coarse aggregate replacement rate is greater, the same time trial The lower the internal measuring point temperature, the lower the stirrup temperature. The recycled concrete beam has better fire resistance than the ordinary concrete beam. At the end of the fire test, with the increase of the replacement rate of recycled coarse aggregate, The results show that the ductility of regenerated concrete beam under high temperature is better than that of ordinary concrete beam. The results of finite element analysis are in good agreement with the experimental results. The theoretical calculation method of shear capacity of recycled concrete beam at high temperature and Design calculation formulas are feasible and can meet the requirements of test and engineering design respectively.