高水头弧形钢闸门主框架强度及动力稳定性分析方法研究
发布时间：2019-05-15 21:59
【摘要】：弧形钢闸门是水利水电工程枢纽的调节结构和咽喉,随着高坝大库建设的发展,弧形钢闸门向着高水头方向发展,承受的总水压力越来越大。对于高水头弧形钢闸门,主框架的薄壁主梁的梁高被设计的越来越大来承受高水头水荷载,致使其跨高比越来越小,属于分布荷载作用下发生横力弯曲的深梁,从而使主框架成为深梁框架,结构的空间效应十分显著。深梁框架的强度及动力稳定性问题是高水头弧形钢闸门及许多钢结构工程设计中亟待研究和解决的重要课题,本文围绕这两个核心问题展开研究,针对现有分析方法的不足之处,以提高计算精度和计算效率为目标,改进深梁框架的强度及动力稳定性分析方法,使之能适应高水头弧形钢闸门设计的需要,具体工作如下:(1)主框架薄壁深梁横力弯曲强度分析方法研究主框架薄壁深梁横力弯曲强度分析方法研究:::以高水头弧形钢闸门主框架的单轴对称工字形截面薄壁深梁为研究对象,针对其横力弯曲强度计算这一经典力学问题进行系统研究,建立了薄壁深梁横力弯曲的弯剪耦合力学模型,据此提出各应力分量的理论计算公式;分析了不同支座约束、荷载分布、跨高比和截面特征时截面剪切变形对弯应力的影响规律,揭示了薄壁深梁的弯剪耦合机理;提出了工字形截面梁临界跨高比的计算公式,为细长梁和深梁的划分提供理论依据。通过数值算例验证了本文方法的精度并应用该方法对某高水头弧形钢闸门的薄壁深梁进行强度校核。本文提出的薄壁深梁横力弯曲强度分析方法是对Timoshenko深梁理论的丰富和完善,可为薄壁深梁的强度分析和设计提供系统的理论分析方法,克服纯弯曲理论分析结果的不安全性。(2)不考虑阻尼的主框架动力稳定性分析方法研究:提出应用动力刚度法对不考虑阻尼的框架结构进行动力稳定性分析,核心思想为:首先将复杂的结构动力稳定性分析问题(保守问题)转化为承受特定不变荷载的结构的自由振动分析问题,降低求解难度;然后应用动力刚度法对受载结构进行自由振动分析获得固有振动频率;最后应用受载结构的固有振动频率确定动力不稳定区域。动力刚度法是一种精确数值方法,对于框架结构,一个杆件离散为一个单元即可得到精确数值解,并且求解效率高,是分析不考虑阻尼的框架结构动力稳定性的一种精确、高效的工程实用方法,克服以低阶多项式作为形函数的有限元法求解精度差及求解效率低的问题。通过数值算例验证了动力刚度法的求解精度及求解效率。(3)考虑阻尼的主框架动力稳定性分析方法研究:提出精确有限元法对考虑阻尼的框架结构进行动力稳定性分析,核心思想为:提出应用满足杆件自由振动微分方程的精确形函数作为有限元法的形函数,应用基于该精确形函数的有限元法(称为精确有限元法)对框架结构进行动力稳定性分析,考虑阻尼对结构动力稳定性的影响,形成结构动力稳定性问题的有限元方程;应用基于弗洛凯理论的谐波平衡法获得临界频率方程式,最终化为一个广义特征值的求解问题,进而确定动力不稳定区域。精确有限元法是一种精确数值方法,对于框架结构,一个杆件离散为一个单元即可得到精确数值解,并且求解效率高,是分析框架结构动力稳定性问题(保守问题和非保守问题)的一种精确、高效的工程实用方法,克服以低阶多项式作为形函数的有限元法求解精度差及求解效率低的问题。通过数值算例验证了精确有限元法的求解精度及求解效率。(4)动力刚度法及精确有限元法在框架结构动力稳定分析中的应用动力刚度法及精确有限元法在框架结构动力稳定分析中的应用:①应用动力刚度法和精确有限元法分析了深梁的截面剪切变形及转动惯量、阻尼、静力荷载因子α和动力荷载因子β对框架结构动力稳定性的影响规律。②对某高水头弧形钢闸门的动力稳定性问题进行了研究,建立了合理的空间框架简化模型;应用动力刚度法和精确有限元法分析了空间框架简化模型的动力稳定性,确定了动力不稳定区域;通过与模型试验相关数据的对比,判断其是否发生参数共振,为闸门的安全运行提供参考。③应用动力刚度法和精确有限元法探讨了结构的高阶动力不稳定区域的求解规模问题,进一步说明这两种方法求解高阶动力不稳定区域的优势。
[Abstract]:The arc-shaped steel gate is the regulating structure and the throat of the water conservancy and hydropower project hub. With the development of the construction of the large reservoir of the high dam, the arch-shaped steel gate is developed in the direction of high water head, and the total water pressure is increasing. for the high-head arc-shaped steel gate, the beam height of the thin-wall main beam of the main frame is more and more large to bear the high-head water load, so that the cross-span height ratio is smaller and smaller, The spatial effect of the structure is very significant. The strength and dynamic stability of the deep beam frame is an important subject to be studied and solved in the design of high-head arc-shaped steel gate and many steel structures. In order to improve the calculation accuracy and the calculation efficiency, the strength and the dynamic stability analysis method of the deep beam frame are improved, so that the method can adapt to the design requirements of the high-head arc-shaped steel gate, and the specific work is as follows: (1) The method for analyzing the transverse force bending strength of the thin-wall deep beam of the main frame is studied by the method of the method for analyzing the transverse force bending strength of the thin-wall deep beam of the main frame. Based on the study of the classical mechanics problem of the transverse force bending strength of the thin-wall deep beam, the mechanical model of the bending and shear coupling of the thin-wall deep beam is established, and the theoretical calculation formula for each stress component is proposed, and the constraint and load distribution of the different support are analyzed. The influence of the cross-section shear deformation on the bending stress in the cross-section and cross-section characteristics is regular, and the bending and shear coupling mechanism of the thin-wall deep beam is revealed. The calculation formula of the critical span height ratio of the I-shaped section beam is proposed, which provides a theoretical basis for the division of the elongated beam and the deep beam. The accuracy of this method is verified by a numerical example, and the strength of a thin-wall deep beam of a high-head arc-shaped steel gate is checked by using the method. The method of thin-wall deep beam transverse force bending strength is rich and perfect for Timoshenko deep beam theory, which can provide a theoretical analysis method for the strength analysis and design of thin-wall deep beam, and can overcome the unsafety of the analysis result of pure bending theory. (2) The dynamic stability analysis of the main frame with the damping is not considered: the dynamic stability analysis of the frame structure with no damping is proposed by applying the dynamic stiffness method, and the core idea is as follows: The method comprises the following steps of: firstly, converting a complex structural dynamic stability analysis problem (conservative problem) into a free vibration analysis problem of a structure which is subjected to a specific constant load, and reducing the solving difficulty; and then carrying out free vibration analysis on the loaded structure to obtain the natural vibration frequency by applying the dynamic stiffness method; Finally, the dynamic instability region is determined by the natural vibration frequency of the load-receiving structure. The dynamic stiffness method is an accurate numerical method. For the frame structure, a member can be discretized into a single unit to obtain the accurate numerical solution, and the solution efficiency is high. It is an accurate and efficient engineering practical method for analyzing the dynamic stability of the frame structure without considering the damping. The method for solving the problem of low accuracy and low solution efficiency is overcome by using the low-order polynomial as the shape function. The solution precision and efficiency of the dynamic stiffness method are verified by numerical examples. (3) The method of dynamic stability analysis of the main frame with damping is studied: the finite element method is proposed to analyze the dynamic stability of the frame structure with damping, and the core idea is that the exact shape function of the differential equation of the free vibration of the rod is put forward as the shape function of the finite element method, The finite element method (called the exact finite element method) based on the exact shape function is used to analyze the dynamic stability of the frame structure, and the influence of the damping on the dynamic stability of the structure is considered, and the finite element equation of the structural dynamic stability problem is formed. The critical frequency equation is obtained by the harmonic balance method based on the Floquet theory, and finally the problem of solving a generalized eigenvalue is solved, and the unstable region of the power is determined. The exact finite element method is an accurate numerical method. For the frame structure, a member can be discretized into a single unit to get the accurate numerical solution, and the solution efficiency is high. It is an accurate method for analyzing the dynamic stability of the frame structure (conservative and non-conservative problems). In order to solve the problem of low accuracy and low solution efficiency of the finite element method with the low-order polynomial as the shape function, a practical and practical method is proposed. The solution precision and efficiency of the accurate finite element method are verified by numerical examples. (4) The application of the dynamic stiffness method and the accurate finite element method to the dynamic stability analysis of the frame structure: The influence of shear deformation and moment of inertia, damping, static load factor and dynamic load factor on the dynamic stability of the frame structure is analyzed by the dynamic stiffness method and the exact finite element method. The dynamic stability of a high-head arc-shaped steel gate is studied, a reasonable space frame simplification model is established, the dynamic stability of the simplified model of the space frame is analyzed by using the dynamic stiffness method and the accurate finite element method, and the power unstable region is determined; By comparing the data with model test, it is judged whether the parameter resonance occurs, and provides a reference for the safe operation of the gate. By using the dynamic stiffness method and the exact finite element method, the scale problem of the high-order dynamic instability region of the structure is discussed, and the advantages of the two methods for solving the high-order dynamic instability region are further explained.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV663.4;TV31
本文编号：2477796
[Abstract]:The arc-shaped steel gate is the regulating structure and the throat of the water conservancy and hydropower project hub. With the development of the construction of the large reservoir of the high dam, the arch-shaped steel gate is developed in the direction of high water head, and the total water pressure is increasing. for the high-head arc-shaped steel gate, the beam height of the thin-wall main beam of the main frame is more and more large to bear the high-head water load, so that the cross-span height ratio is smaller and smaller, The spatial effect of the structure is very significant. The strength and dynamic stability of the deep beam frame is an important subject to be studied and solved in the design of high-head arc-shaped steel gate and many steel structures. In order to improve the calculation accuracy and the calculation efficiency, the strength and the dynamic stability analysis method of the deep beam frame are improved, so that the method can adapt to the design requirements of the high-head arc-shaped steel gate, and the specific work is as follows: (1) The method for analyzing the transverse force bending strength of the thin-wall deep beam of the main frame is studied by the method of the method for analyzing the transverse force bending strength of the thin-wall deep beam of the main frame. Based on the study of the classical mechanics problem of the transverse force bending strength of the thin-wall deep beam, the mechanical model of the bending and shear coupling of the thin-wall deep beam is established, and the theoretical calculation formula for each stress component is proposed, and the constraint and load distribution of the different support are analyzed. The influence of the cross-section shear deformation on the bending stress in the cross-section and cross-section characteristics is regular, and the bending and shear coupling mechanism of the thin-wall deep beam is revealed. The calculation formula of the critical span height ratio of the I-shaped section beam is proposed, which provides a theoretical basis for the division of the elongated beam and the deep beam. The accuracy of this method is verified by a numerical example, and the strength of a thin-wall deep beam of a high-head arc-shaped steel gate is checked by using the method. The method of thin-wall deep beam transverse force bending strength is rich and perfect for Timoshenko deep beam theory, which can provide a theoretical analysis method for the strength analysis and design of thin-wall deep beam, and can overcome the unsafety of the analysis result of pure bending theory. (2) The dynamic stability analysis of the main frame with the damping is not considered: the dynamic stability analysis of the frame structure with no damping is proposed by applying the dynamic stiffness method, and the core idea is as follows: The method comprises the following steps of: firstly, converting a complex structural dynamic stability analysis problem (conservative problem) into a free vibration analysis problem of a structure which is subjected to a specific constant load, and reducing the solving difficulty; and then carrying out free vibration analysis on the loaded structure to obtain the natural vibration frequency by applying the dynamic stiffness method; Finally, the dynamic instability region is determined by the natural vibration frequency of the load-receiving structure. The dynamic stiffness method is an accurate numerical method. For the frame structure, a member can be discretized into a single unit to obtain the accurate numerical solution, and the solution efficiency is high. It is an accurate and efficient engineering practical method for analyzing the dynamic stability of the frame structure without considering the damping. The method for solving the problem of low accuracy and low solution efficiency is overcome by using the low-order polynomial as the shape function. The solution precision and efficiency of the dynamic stiffness method are verified by numerical examples. (3) The method of dynamic stability analysis of the main frame with damping is studied: the finite element method is proposed to analyze the dynamic stability of the frame structure with damping, and the core idea is that the exact shape function of the differential equation of the free vibration of the rod is put forward as the shape function of the finite element method, The finite element method (called the exact finite element method) based on the exact shape function is used to analyze the dynamic stability of the frame structure, and the influence of the damping on the dynamic stability of the structure is considered, and the finite element equation of the structural dynamic stability problem is formed. The critical frequency equation is obtained by the harmonic balance method based on the Floquet theory, and finally the problem of solving a generalized eigenvalue is solved, and the unstable region of the power is determined. The exact finite element method is an accurate numerical method. For the frame structure, a member can be discretized into a single unit to get the accurate numerical solution, and the solution efficiency is high. It is an accurate method for analyzing the dynamic stability of the frame structure (conservative and non-conservative problems). In order to solve the problem of low accuracy and low solution efficiency of the finite element method with the low-order polynomial as the shape function, a practical and practical method is proposed. The solution precision and efficiency of the accurate finite element method are verified by numerical examples. (4) The application of the dynamic stiffness method and the accurate finite element method to the dynamic stability analysis of the frame structure: The influence of shear deformation and moment of inertia, damping, static load factor and dynamic load factor on the dynamic stability of the frame structure is analyzed by the dynamic stiffness method and the exact finite element method. The dynamic stability of a high-head arc-shaped steel gate is studied, a reasonable space frame simplification model is established, the dynamic stability of the simplified model of the space frame is analyzed by using the dynamic stiffness method and the accurate finite element method, and the power unstable region is determined; By comparing the data with model test, it is judged whether the parameter resonance occurs, and provides a reference for the safe operation of the gate. By using the dynamic stiffness method and the exact finite element method, the scale problem of the high-order dynamic instability region of the structure is discussed, and the advantages of the two methods for solving the high-order dynamic instability region are further explained.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV663.4;TV31
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