汽机基础钢筋混凝土横梁动刚度研究

发布时间：2018-06-09 01:42

本文选题：汽机基础 + 动刚度　；参考：《北方工业大学》2017年硕士论文

【摘要】：汽轮发电机基础作为发电机机组的支撑结构,是机组稳定运行、正常发电的重要保证条件之一。基础本身动刚度、自振特性对结构动力响应分析有决定性作用。汽机基座的台板横梁往往直接承受转子动力荷载,在动力分析中起到关键作用,其动力响应也最值得关注。基础中作为轴承支座的钢筋混凝土横梁结构,在工程分析设计中,其弹性模量值往往采用素混凝土弹性模量值,与钢筋混凝土结构真实弹模值存在不可忽略的误差。因此,对结构动刚度测试结果造成较大影响,从而使汽机基础动力特性分析值与工程实际不符。实际工程中,钢筋混凝土构件弹性模量取值受众多因素的影响,配筋率不仅是直接影响因素,而且是重要影响因素之一。对于汽轮机这种大型钢筋混凝土结构来说,钢筋配置直接影响发电机轴承座动刚度,进而影响结构动力响应及结构稳定性,因此对钢筋混凝土横梁的配筋率与结构弹性模量之间关系的研究,对整个结构动力分析都十分重要。本文中研究对象选自某汽轮发电机组隔振基础结构,做了一系列研究,主要研究内容及成果如下:1、对该汽机基础工程动刚度进行现场实测,并以该工程为原型建立缩尺模型,进一步测试其动刚度是否能满足正常运行要求。结合现场实测与试验模型测试,对该汽机基础的动刚度进行综合分析、评判。此外,就提高轴承横梁动刚度对改善整体结构动力特性重要性进行分析,并从结构设计角度对提高轴承横梁动刚度进行探究。2、设计了不同配筋率的混凝土试块,以试验方法研究分析了钢筋混凝土结构配筋率对弹性模量取值的影响,拟合得出配筋试块弹性模量回归方程。进而通过试验与有限元模拟计算相结合的方法,研究了汽机基础横梁结构配筋率对弹性模量取值的影响,拟合出以配筋率为自变量的弹性模量试验值的回归方程,与配筋试块试验回归方程进行对比分析,验证了该公式的合理性。3、基于弹性理论,推导了钢筋混凝土复合弹性模量理论计算公式,与配筋试块及横梁试验回归方程进行对比,分析结果表明两者计算结果较吻合,为工程设计及后续汽机基础有限元模拟分析提供参数取值依据。4、根据上述对汽机基础横梁结构的研究,采用有限元模拟建立某汽机基础整体模型,对该汽机基础结构进行了模态分析,并对轴承座处横梁进行谐响应和动刚度分析。
[Abstract]:As the supporting structure of generator unit, turbogenerator foundation is one of the important guarantee conditions for the unit to operate stably and generate electricity normally. The dynamic stiffness and natural vibration characteristics of the foundation play a decisive role in the dynamic response analysis of the structure. The cross-beam of the turbine pedestal often bears the rotor dynamic load directly, and plays a key role in the dynamic analysis, and its dynamic response is also the most worthy of attention. In the engineering analysis and design of reinforced concrete crossbeam structure which is used as bearing support, the elastic modulus value of plain concrete is often used, which is not negligible with the real elastic modulus value of reinforced concrete structure. Therefore, the test results of dynamic stiffness of the structure are greatly affected, so that the analysis value of the dynamic characteristics of the turbine foundation is not in accordance with the engineering practice. In practical engineering, the elastic modulus of reinforced concrete members is affected by many factors. Reinforcement ratio is not only a direct factor, but also one of the important factors. For the large reinforced concrete structure such as steam turbine, the reinforcement configuration directly affects the dynamic stiffness of the generator bearing seat, and then affects the dynamic response of the structure and the structural stability. Therefore, the study of the relationship between the reinforcement ratio and the elastic modulus of reinforced concrete beams is very important to the dynamic analysis of the whole structure. In this paper, the object of study is selected from the vibration isolation infrastructure of a turbine-generator unit, and a series of studies have been done. The main research contents and results are as follows: 1. The dynamic stiffness of the turbine foundation project is measured on the spot, and the scale model is established based on the prototype. Further test whether the dynamic stiffness can meet the normal operation requirements. Combined with field measurement and test model test, the dynamic stiffness of the turbine foundation is comprehensively analyzed and evaluated. In addition, the importance of increasing the dynamic stiffness of the bearing beam to improve the dynamic characteristics of the whole structure is analyzed, and from the structural design point of view to improve the dynamic stiffness of the bearing beam, the concrete test blocks with different reinforcement ratios are designed. The influence of reinforcement ratio on elastic modulus of reinforced concrete structure is studied by means of test method, and the regression equation of elastic modulus of reinforced concrete structure is obtained by fitting. Then the influence of reinforcement ratio on elastic modulus is studied by combining test with finite element simulation, and the regression equation of test value of elastic modulus with reinforcement ratio as independent variable is fitted. Comparing with the regression equation of reinforced concrete test, the rationality of the formula is verified. Based on the elastic theory, the formula for calculating the composite elastic modulus of reinforced concrete is derived, and the regression equation is compared with the regression equation of the reinforced concrete test block and beam test. The analysis results show that the calculated results are in good agreement with each other, which provides a parameter basis for engineering design and subsequent finite element simulation analysis of turbine foundation. According to the above research on the beam structure of turbine foundation, The integral model of a steam turbine foundation was established by finite element simulation. The modal analysis of the turbine foundation structure was carried out, and the harmonic response and dynamic stiffness of the beam at the bearing seat were analyzed.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU476.1;TM62

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