体外预应力对波形钢腹板PC组合简支箱梁动力特性影响的试验研究

发布时间：2018-10-18 18:24

【摘要】：由于波形钢腹板PC组合箱梁的钢腹板很薄,故无法在腹板中布置体内预应力筋,而用大量的体外预应力筋来替代体内预应力筋,因此是非常有必要研究体外预应力对波形钢腹板PC组合箱梁动力特性的影响。本文采用模型试验梁试验、理论公式计算以及ANSYS有限元分析就体外预应力对单跨等截面波形钢腹板PC组合简支箱梁动力特性的影响规律进行了较系统的研究,主要完成工作及研究结论为:(1)参考经典结构动力学,考虑了波形钢腹板箱梁剪力效应和剪力滞效应以及体外预应力的各项损失,并且考虑预应力对梁体抗弯刚度的影响,扩充并修正了体外预应力对传统混凝土腹板箱梁自振特性计算公式,推导出波形钢腹板PC组合简支箱梁的体外预应力筋在直线形、单折线形和双折线形布置下梁体的自振频率计算公式。(2)设计和制作了5m的等截面简支波形钢腹板模型试验梁,测试了体外筋在八个不同张拉工况下模型试验梁的第一阶自振频率,模型试验结果表明:随着体外筋初始张拉力的增大,模型试验梁的第一阶自振频率也将增大。(3)针对制作的波形钢腹板模型试验梁,应用本文推导的波形钢腹板PC组合简支箱梁自振频率的公式计算模型试验梁体外筋在八个不同张拉工况下的第一阶自振频率,结果表明当体外预应力筋有效张拉力的增大,梁体第一阶自振频率也将增大。结果与试验梁第一阶自振频率测试值保持了一致的增长趋势并且数值差别不大,证明了推导的理论公式能较正确的计算波形钢腹板PC组合简支箱梁的自振频率。(4)建立模型试验梁的ANSYS有限元计算模型,并计算相应的体外筋在八个不同工张拉况下的模型试验梁的第一阶自振频率,结果表明:有限元的计算结果与试验梁测试结果保持了一致的趋势且数值较接近,二者相对误差在9%左右,说明本文建立的ANSYS有限元模型能正确的模拟模型试验梁的自振特性。(5)应用理论公式以及ANSYS有限元分析研究不同体外预应力筋布置参数对波形钢腹板PC组合简支箱梁自振频率的影响规律,结果表明:体外筋布置参数不同时,对波形钢腹板PC组合简支箱梁的第一阶自振频率都有一定的影响。(6)通过对体外预应力筋的振动特性的分析研究,得出体外筋自由长度应尽量控制在12m以内,这样就使得体外筋频率与桥梁及外载频率互相错开,很好的解决了体外筋与梁体的共振问题,并且通过频率法可反算出体外筋的有效张拉应力,无论对于波形钢腹板箱梁的施工还是后期的加固养护都有极大的意义。
[Abstract]:Because of the thin steel web of PC composite box girder with corrugated steel webs, it is impossible to arrange the internal prestressing tendons in the webs, and a large number of external prestressing tendons are used to replace the internal prestressing tendons. Therefore, it is necessary to study the influence of external prestress on the dynamic characteristics of PC composite box girder with corrugated steel web. In this paper, the influence of external prestress on the dynamic characteristics of single span corrugated steel webs with PC composite simply supported box girder is systematically studied by using model test beam test, theoretical formula calculation and ANSYS finite element analysis. The main works and conclusions are as follows: (1) with reference to the classical structural dynamics, the shear effect and shear lag effect of corrugated steel web box girder and the loss of external prestressing force are considered, and the influence of prestress on the bending stiffness of beam is considered. The formula for calculating the natural vibration characteristics of traditional concrete web box girder by external prestressing is expanded and modified. The external prestressing tendons of PC composite box girder with corrugated steel webs are derived in a linear form. The formulas for calculating the natural frequencies of beam body under the arrangement of single and double folded lines are given. (2) A simple supported steel web model test beam of 5m with equal section is designed and fabricated. The first order natural vibration frequency of the model test beam under eight different tension conditions was measured. The results of the model test show that the initial tensile force increases with the increase of the initial tensile force of the external tendon. The first natural vibration frequency of the model test beam will also increase. (3) for the model test beam made of corrugated steel web, Using the formula derived in this paper for calculating the natural vibration frequency of PC composite box girder with corrugated steel webs, the first order natural vibration frequency of external tendons under eight different tensioning conditions is tested. The results show that when the effective tensile force of external prestressing tendons is increased, The first natural frequency of beam will also increase. The results are consistent with the measured values of the first order natural vibration frequency of the test beam, and there is no significant difference between the results and the experimental results. It is proved that the derived theoretical formula can correctly calculate the natural vibration frequency of PC composite box girder with corrugated steel webs. (4) the ANSYS finite element calculation model of the model test beam is established. The first order natural vibration frequencies of the model test beams under eight different tensile conditions are calculated. The results show that the calculated results of the finite element method are consistent with the test results and the values are close to those of the test beams. The relative error between them is about 9%. The ANSYS finite element model established in this paper can correctly simulate the natural vibration characteristics of the model test beam. (5) apply the theoretical formula and ANSYS finite element analysis to study the effect of different external prestressing tendons layout parameters on the waveform steel web PC composite simple support box The influence law of beam natural vibration frequency, The results show that the first order natural vibration frequency of PC composite box girder with corrugated steel webs is affected by the different arrangement parameters of external tendons. (6) the vibration characteristics of external prestressed tendons are analyzed and studied. It is concluded that the free length of external tendons should be controlled within 12m as far as possible, so that the frequencies of external tendons, bridges and external loads are staggered, and the resonance between external tendons and beams is well solved. And the effective tensile stress of external tendons can be calculated by frequency method, which is of great significance for the construction of corrugated steel web box girder and the reinforcement and maintenance of the later stage.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.216

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