【作者】 周小勇；

【导师】 方秦汉； 金文成；

【作者基本信息】 华中科技大学 ， 桥梁与隧道工程， 2008， 博士

【摘要】 目前,桥梁结构的整体分析一般都是建立在平面或空间杆系有限元理论基础上,部分采用三维实体单元分析但尚不成熟。对于普通钢筋混凝土和简单预应力混凝土桥梁,结构计算采用杆系有限元加局部三维分析基本够用。但对于特殊造型桥梁、多向预应力体系桥梁及弯、宽桥,这些以杆系有限元理论为基础的分析方法已不能完全满足设计者的需要。随着大跨度和复杂的桥型不断涌现、计算机技术的高速发展、有限元理论的逐步完善,全桥结构三维仿真分析(SSEB)已进入实质性研发阶段。通过三维实体结构仿真分析,模拟桥梁构件的空间状态,真实反映边界条件和荷载状况,可得到更详尽、精确和可靠的分析结果,以指导设计和施工。本文基于大型通用有限元软件ANSYS和MATLAB,探索三维实体模型下进行PC桥梁结构整体仿真分析的途径,研究其关键理论及专业模块开发技术。重点研究了预应力筋的模拟、预应力效应的等效转换和桥梁截面切片技术。研究成果可广泛应用于PC桥梁的三维仿真领域,具有较大的理论意义和工程实用价值。本文在如下几个方面进行了理论、数值研究,并取得了一些研究成果:1、根据PC桥梁设计与实际筋施工中预应力布置的特点,成功引入CAGD中的非均匀B-Spline模拟空间曲线型预应力筋,成为课题研究的理论前提。2、研究了桥梁结构中预应力损失产生机理,推导出任意空间曲线型预应力筋的摩擦损失和考虑反摩阻力影响的锚具回缩损失的数值公式;3、根据预应力等代荷载原理,实现了预应力效应,即锚固端集中力和体内预应力径向力在实体单元中的等效转换,该方法对各类实体单元具有通用性;4、鉴于桥梁截面多样化特点,提出一套约束Delaunay三角网格划分方法,并针对实体模型,研究了截面几何特性、截面内力和正截面抗弯承载能力计算理论。5、实现了实体模型下的截面切片可视化以及相关配套技术,为桥梁精细化分析和处理大容量结果分析数据提供了一条可选途径。6、基于WINDOWS消息处理机制,实现了对ANSYS软件的无缝控制。采用Fortran语言和C++面向对象编程,开发出基于ANSYS与MATLAB平台的PC桥梁分析模块,实现了实体模型下的曲线PC箱梁桥的静力分析。由于以ANSYS和MATLAB平台为依托,上述成果的实现只编写了少量程序代码,却能利用ANSYS前、后处理、求解器和MATLAB C++数学库等强大功能,说明本文尝试的软件开发途径是有效的。本文的研究对于提高PC桥梁结构设计水平和效率,普及三维实体有限元技术的应用,拓展专业模块软件的开发途径具有重要的理论意义和实用价值。更多还原

【Abstract】 Currently, most of the analyses on the structural simulation for entire bridge are based on the theory of 2D or 3D beam Finite Element Method (FEM), whereas solid element method is seldom to be based on due to its immaturity. It is feasible to use beam FEM combined with partial solid FEM for RC bridges or simple PC bridges simulation, but when it comes to the special shape bridge and milt-directional curved prestressed bridge, such theories cannot fully meet the needs of designers. With the rapid increase in large span and complicate bridge forms, as well as the development in computer technology and FEM theory, the Structural 3D Simulation for Entire Bridge (SSEB) has stepped onto its substantial stage of research and development. By means of SSEB, boundary condition and load situation can be real reflected, and more accurate and reliable analysis results can be obtained to assist design and construction.Based on FEM software ANSYS and MATLAB, the simulation analysis approach for 3D entity model of PC bridge structures and relevant key theories as well as program developing strategies were studied in this paper. The research is focused on the line shape prestressing tendon simulation, equal translation of prestressed effect and cross-section slice technology. The research results, which can be widely applied in 3D simulation of PC bridges, will have its theoretical and practical significance.Theoretical and numerical researches in this paper are carried out in the following aspects, with some achievements accomplished:1. Considering the characteristics of prestressing tendon layout in bridge design and construction, non-uniform B-Spline in CAGD was successfully introduced into simulating 3D curved prestressing tendon, and it became the theoretical premise of this research as such.2. A numerical formula to calculate the prestressed losses due to friction and the pipeline local defection of 3D curved prestressed tendons was deduced. Also, with consideration to unfriction, another formula to calculate the anchorage losses was deduced in this paper.3. According to prestress equipollent load theory, prestressed effect was realized. That means the concentrated force on the fixed end of anchorage and the internal prestressing radial force could be transformed equivalently on entity elements. This method can be applied in various solid elements.4. In view to the diversity of bridge sections, a restraint Delaunay triangle net division method was brought up. Theory of section geometrical feature, section endogen force and right section bending resistance capacity calculation were studied to solid modal.5. The visualization technique of cross-section slice and matching auxiliary techniques for entity model were put forward and realized by programming, and provides a method for accurate analysis and analysis with high-capacity results data.6. Based on the message-handling mechanism of Windows, the command line of ANSYS was successfully intercepted. By applying FORTRAN language and C++ object-oriented programming, a professional analysis modular with PC structure handling ability based on ANSYS and MATLAB was explored. Therefore, the static analysis for PC box girder on entity model could be carried out.Only a few codes were compiled for accomplishing the above achievements, but powerful capabilities of ANSYS such as pre/post processors, solvers, and MATLAB C++ mathematical function library could be used fully. Since the task was built upon the ANSYS and MATLAB platform, it means the attempt of software development in this paper was rather effective.The paper has profound theoretical and practical significance in improving the design level and efficiency of PC bridges, popularizing the application of finite element method (FEM), and promoting the development of professional software.更多还原