基于损伤理论的预应力混凝土梁弹性模量分析

ELASTIC MODULUS OF PRESTRESSEG CONCRETE BEAM BASED ON DAMAGE MECHANICS

针对混凝土材料在成型过程中不可避免的存在微裂缝和微孔隙的特点,定义了基于混凝土弹性模量表达的负损伤变量,把负损伤变量引入到损伤本构方程中,采用损伤力学附加荷载有限元法对体外预应力混凝土梁的受力过程进行了分析,得到了预应力混凝土梁的弹性模量随预应力变化的规律。结果表明:引入负损伤变量可以很好地模拟混凝土弹性模量的变化,特别是施加预应力阶段;运用求得的混凝土弹性模量对某试验梁的自振频率进行分析,计算结果在变化趋势上是和试验结果相一致,并且误差在可以接受的范围之内。

It＇s not avoidable of the concrete material to produce micro-fractures and micro-hole at the shaping process.In the light of this feature,the author defines a negative damage variable based on the concrete elastic modulus,and introduces the negative damage variable to the damage constitutive equation.The relation between the elastic modulus of the prestressed concrete beam with various prestressing force is obtained by analyzing the dynamic behaviors of the externally prestressed concrete structures using the damage mechanics and load finite-element method.The results indicate： the damage theory with the negative damage variation based on the concrete elastic modulus can predict well the variation of the concrete elastic modulus,especially at the stage in application of pre-stress;the natural frequency determined by the elastic modulus in the corresponding state is consistent with the test results in trend,and the error is acceptable.