应用大型有限元分析软件ANSYS建立一根已经服役20年的既有预应力混凝土后张板梁单元的有限元模型,采用弹簧单元Combin 39模拟预应力钢筋和混凝土间的粘结滑移效应,通过调整该弹簧单元的刚度来控制预应力钢筋和混凝土间的粘结程度.在模型中同时考虑了预应力瞬时损失和长期损失,较为精确的对既有预应力混凝土结构进行有限元模拟.对该模型进行构件的弹塑性变形、混凝土开裂到极限承载力破坏的全过程分析,得到的结果与试验结果有较高的吻合度,进一步表明该模拟方法的合理性和有效性,为预应力结构精细化建模分析提供一定的参考.%A finite element simulation model of a post tensioned prestressed concrete beam which has served 20 years was developed by ANSYS software .The spring unit Combin 39 was adopted to simulate the bond slip effect between pre-stressed steel and concrete ,through adjusting the spring element stiffness to control the degree of bonding between pre-stressed steel and concrete .The model considers instantaneous loss and the long-term loss ,which makes the finite ele-ment simulation of prestressed concrete structure more accurate .The procedure can predict the responses of post-tensioned concrete structures throughout the service load history ,such as elastic and plastic deformation ,cracking and damage pat-terns .Numerical examples of beams model are presented .The comparison of computed results with experimental ones shows good agreement ,demonstrating the efficiency of the proposed model ,which provided certain reference for precise modeling of prestressed structure .
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