【摘要】 本文进行了两根无粘结预应力混凝土简支梁的动力试验,结果表明:随着预应力的增加,梁的频率逐渐增大,当预应力增加到一定程度时,梁的频率稍有下降。这与经典动力学理论中随着轴压力增加,梁自振频率减小的结论相反。本文从结构动力学的基本原理和损伤理论出发,对预应力混凝土梁的自振频率与预应力的关系进行了研究,利用损伤变量修正了预应力对混凝土弹性模量的影响,提出了基于损伤的预应力混凝土梁振动频率公式,计算结果表明:随着力筋预应力的变化,梁频率的变化趋势与试验结果一致,理论曲线与试验曲线符合较好,一阶频率的计算具有较高精度。在工程实践中,测出构件的振动频率即可根据本文提出的公式推算出其实际预应力的大小。更多还原

【Abstract】 Two unbonded prestressed concrete beams were made to investigate the dynamic characteristic.The test results indicate that the frequencies of these beams are increasing gradually with the increasing of the prestress force in the certain range,then the frequencies decreasing slightly when the prestress force out of the range.While in the classical dynamics,the natural frequencies of the beams will be decreasing with the increasing of the axial force when the isotropic homogeneous materials beams bear the axial force.Thus the results from tests are inconsistent with the classical theory.Therefore,this paper embarks from the structure dynamics basic principle and the damage theory,using the elasticity coefficient change,the formula of the prestressed beam’s natural frequency has been obtained.The formula results indicate that frequency changing tendency compared with test result is consistent,the result precision of the first frequency is also good.更多还原