中文摘要：

为建立预应力混凝土梁模态分析的有限元模型，以ANSYS有限元分析软件为例，提出预应力混凝土梁式结构在利用大型有限元软件进行模态分析时，可采用初应变法施加预应力，并且将混凝土受到的预压力影响转化为对单元材料弹性模量的影响，通过对变弹性模量的有限元模型进行模态分析，得到预应力混凝土梁在各级预应力下的自振频率和振型．通过与试验值对比可知，改进后的有限元模型可以用于预应力混凝土梁的模态分析。

英文摘要：

In order to create the modal analysis finite element model of prestressed concrete beams, a new analysis method has been proposed by the example of ANSYS finite element software. The prestressing force of beam is used by initial strain when the prestressed concrete beam modal is analyzed with finite element software. The perstressing force influence of the beam is changed to the impact of element materials elastic modulus. The frequencies and modals of prestressed con- crete beams using ANSYS procedure is analyzed by varied modulus. The calculated natural frequencies at all levels prest- essing force fit close with the experimental results. It shows that the modified finite element analysis model is feasible.