基于正交异性材料的预应力梁频率的试验研究

进行了一根无粘结预应力简支梁的动力试验,结果表明:预应力梁的固有频率随着预应力的增加而增加,这与Clough提出的轴力作用下各向同性材料梁的理论分析结果相反。其原因是传统的结构分析方法将混凝土视为各向同性、均质的线弹性材料。但是对预应力混凝土结构进行动力分析和检测,要求计算结果必须具有相对高的计算精度。为此该文从混凝土的微观结构入手,将预应力混凝土梁看作各向异性复合材料梁,采用正交异性的线弹性本构模型进行分析,将复合材料梁的刚度视为钢筋混凝土梁的刚度与预应力筋等效刚度之和,然后对预应力混凝土梁的频率与预应力的关系进行分析计算,计算结果与试验结果吻合较好。同时,利用该文提出的分析方法对Saiidi等人的试验梁进行了分析对比,其计算结果与其试验值也符合较好。

EXPERIMENTAL RESEARCH ON FREQUENCIES OF PRE-STRESSED CONCRETE BEAM USING ORTHOTROPIC MATERIAL CONSTITUTION

The dynamic experiment of a non-bonded full pre-stressed concrete beam was carried out. The experimental results indicated that the frequencies of the beam increase with the prestressing force increases. The results were different from those of dynamic characteristics which were put forward by Clough about isotropic material beam subjected compressive axial force. The reason is that the beams are considered as isotropic, homogeneous and linear elastic material by the traditional analysis method. Thusly, it requests more accurate results in analysis of pre-stressed concrete frequencies. The constitutive mode of pre-stressed concrete member is analyzed based on microstructure of concrete. Meanwhile, the bending deformation stiffness of the beam is regarded as the sum of the equivalent stiffness of the prestressing tendon and the concrete beam. The orthotropic linear elastic mode is used to analyze and calculate the relation between the dynamic frequency and prestressing force of the concrete beam. The analysis values agree with the test results well. And the beam that Saiidi et al. studied is analyzed by the proposed method. The results are accorded greatly with the experimental data.