本文選題：汽機基礎 + 動剛度　； 參考：《北方工業(yè)大學》2017年碩士論文

【摘要】：汽輪發(fā)電機基礎作為發(fā)電機機組的支撐結構,是機組穩(wěn)定運行、正常發(fā)電的重要保證條件之一。基礎本身動剛度、自振特性對結構動力響應分析有決定性作用。汽機基座的臺板橫梁往往直接承受轉子動力荷載,在動力分析中起到關鍵作用,其動力響應也最值得關注。基礎中作為軸承支座的鋼筋混凝土橫梁結構,在工程分析設計中,其彈性模量值往往采用素混凝土彈性模量值,與鋼筋混凝土結構真實彈模值存在不可忽略的誤差。因此,對結構動剛度測試結果造成較大影響,從而使汽機基礎動力特性分析值與工程實際不符。實際工程中,鋼筋混凝土構件彈性模量取值受眾多因素的影響,配筋率不僅是直接影響因素,而且是重要影響因素之一。對于汽輪機這種大型鋼筋混凝土結構來說,鋼筋配置直接影響發(fā)電機軸承座動剛度,進而影響結構動力響應及結構穩(wěn)定性,因此對鋼筋混凝土橫梁的配筋率與結構彈性模量之間關系的研究,對整個結構動力分析都十分重要。本文中研究對象選自某汽輪發(fā)電機組隔振基礎結構,做了一系列研究,主要研究內容及成果如下:1、對該汽機基礎工程動剛度進行現場實測,并以該工程為原型建立縮尺模型,進一步測試其動剛度是否能滿足正常運行要求。結合現場實測與試驗模型測試,對該汽機基礎的動剛度進行綜合分析、評判。此外,就提高軸承橫梁動剛度對改善整體結構動力特性重要性進行分析,并從結構設計角度對提高軸承橫梁動剛度進行探究。2、設計了不同配筋率的混凝土試塊,以試驗方法研究分析了鋼筋混凝土結構配筋率對彈性模量取值的影響,擬合得出配筋試塊彈性模量回歸方程。進而通過試驗與有限元模擬計算相結合的方法,研究了汽機基礎橫梁結構配筋率對彈性模量取值的影響,擬合出以配筋率為自變量的彈性模量試驗值的回歸方程,與配筋試塊試驗回歸方程進行對比分析,驗證了該公式的合理性。3、基于彈性理論,推導了鋼筋混凝土復合彈性模量理論計算公式,與配筋試塊及橫梁試驗回歸方程進行對比,分析結果表明兩者計算結果較吻合,為工程設計及后續(xù)汽機基礎有限元模擬分析提供參數取值依據。4、根據上述對汽機基礎橫梁結構的研究,采用有限元模擬建立某汽機基礎整體模型,對該汽機基礎結構進行了模態(tài)分析,并對軸承座處橫梁進行諧響應和動剛度分析。
[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.
【學位授予單位】：北方工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU476.1;TM62

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