钢结构安装偏差分析及预防措施

利用大型有限元分析软件ANSYS,分析了某单层双跨钢结构由于安装偏差所造成的结构性能的影响,对不同的偏差组合进行对比分析,并采取一些措施来防止施工过程中最不利的偏差组合发生。     

结构分析中有限元法课程建设研究与实践

随着复杂工程结构及巨型结构的大量出现,在土木、水利等工程专业本科生中加强结构分析能力(包括电算能力)的培养显得尤为迫切。笔者将结构力学中的"矩阵位移法"和弹性力学中的"有限元法"有机结合,按照培养创新型高级专门人才的要求建设了结构分析中的有限元法课程,精心编写并出版了该课程所用的教材和电算程序。根据该课程的特点,对课堂教学、上机实习和考试等教学环节进行了改革,充分发挥教师的主导作用和学生的主体作用,取得了良好的教学效果。     

索结构找形分析的精确单元方法

索找形问题是索结构分析中所要解决的首要问题,在给定边界条件下,所施加的预张力和外部荷载通过调节索的 形状来平衡。本文研究索结构初始形状确定的精确有限单元法,对于常见的荷载形式,构造了线性和非线性两大类共5种 单元,适用于一般的索结构找形计算,并且可以给出精确的解答。本文通过将水平方向和竖直方向的平衡方程解藕,得出 了索单元的精确描述格式,并保证了索结构形状的唯一性。文中以索结构内部结点坐标作为基本未知量,以结点平衡方程 为基本方程,通过直接求解单元的平衡微分方程得到单元刚度矩阵的解析表达式。对于由线性单元组成的索结构,其基本 方程为线性,可直接求解;对于含有非线性单元的索结构,其基本方程为非线性,需通过迭代求解,文中构造了相应的 Newton法迭代格式。本文方法所需单元数目少,计算量小,所得到的解答为数值精确解。数值算例表明本法稳定可靠。     

几何非线性过渡梁元

详细推导了 Ｔｏｔａｌ Ｌａｇｒａｎｇｉａｎ（Ｔ．Ｌ．）描述下空间过渡梁元的切线刚度矩阵。过渡梁元切线刚度矩阵的提出,使局部单层局部双层网壳的计算结果更趋近于实际。     

Deteriorating beam finite element for nonlinear analysis of concrete structures under corrosion

A three-dimensional reinforced concrete (RC) deteriorating beam finite element for nonlinear analysis of concrete structures under corrosion is presented in this study. The finite element formulation accounts for both material and geometrical nonlinearity. Damage modelling considers uniform and pitting corrosion and includes the reduction of cross-sectional area of corroded bars, the reduction of ductility of reinforcing steel and the deterioration of concrete strength due to splitting cracks, delamination and spalling of the concrete cover. The beam finite element is validated with reference to the results of experimental tests carried out on RC beams with corroded reinforcement. The application potentialities of the proposed formulation are shown through the finite element analysis of a statically indeterminate RC beam and a three-dimensional RC arch bridge under different damage scenarios and corrosion penetration levels. The results indicate that the design for durability of concrete structures exposed to corrosion needs to rely on structural analysis methods capable to account for the global effects of local damage phenomena on the overall system performance.     

Shear lag analysis by the adaptive finite element method: 1. Analysis of simple plated structures

Due to the presence of sharp stress gradients, traditional finite element analysis using uniform meshes for the solution of shear lag problems for thin-walled structures is inefficient and will result in inaccurate values of effective breadth ratio. By using the adaptive finite element analysis, it is possible to obtain results with predetermined accuracy with a minimum amount of computational cost. An adaptive finite element analysis procedure is used to deal with the problem of shear lag effects of plated structures with arbitrary dimensions and geometry. This study consists of two parts. In Part 1 of the study, shear lag effects in simple plated structures, such as straight rectangular, single-cell box girders are studied. In Part 2 of the study, the adaptive refinement procedure will be extended to the shear lag analysis of complex plated structures such as core walls with openings, multi-cell box girders and box girders with curve flanges.     

垂直荷载作用下板柱结构计算方法的比较与分析

比较了国内外三个主要规范:英国规范BS8110—1997、美国规范ACI318—2005及我国规范GBJ130—90关于板柱结构在垂直荷载作用下推荐分析方法的不同特点,通过算例考察了不同规范之间、同一规范不同方法之间的差异性,并与杆、壳单元模型的有限元分析方法进行了比较,探讨了实用设计方法与有限元法之间的差别,指出了实用设计方法的不足。通过有关试验成果验证了有限元法的准确性,并提出了设计建议。     

将弧长法应用于结构的几何非线性有限元分析

首先介绍了弧长法的发展及基本理论，随后根据笔者的研究，对其中的几个问题提出了相应的参考意见，最后给出了几个算例。     

自重对索网结构找形的影响

由于现在的计算机硬件和程序开发平台相对于过去有了很大的改进，因此，对于承受均布荷载的索网结构，有必要采用更精确的有限单元模型，对过去的简化两节点模型进行改进。本文作者采用五节点曲线单元模型建立了索网结构有限元模式，自编了程序，对索网结构考虑其自重作用下进行找形，并和原来两节点不考虑自重作用找形分析的结果作了比较，结果证明，自重对找形有一定的影响。     

滆湖服务区综合楼结构分析及其参数选择

针对建筑造型复杂、功能多样的特点,介绍了采用PKPM系列软件中的空间组合结构有限元分析程序SATWE进行复杂高层结构分析的基本步骤以及相关参数的合理选取,从而确保建筑结构的合理性和可靠性。     

A multi-level strategy for successively improved structural analysis of existing concrete bridges: examination using a prestressed concrete bridge tested to failure

This paper describes a multi-level strategy with increased complexity through four levels of structural analysis of concrete bridges. The concept was developed to provide a procedure that supports enhanced assessments with better understanding of the structure and more precise predictions of the load-carrying capacity. In order to demonstrate and examine the multi-level strategy, a continuous multi-span prestressed concrete girder bridge, tested until shear failure, was investigated. Calculations of the load-carrying capacity at the initial level of the multi-level strategy consistently resulted in underestimated capacities, with the predicted load ranging from 25% to 78% of the tested failure load, depending on the local resistance model applied. The initial assessment was also associated with issues of localising the shear failure accurately and, consequently, refined structural analysis at an enhanced level was recommended. Enhanced assessment using nonlinear finite element (FE) analysis precisely reproduced the behaviour observed in the experimental test, capturing the actual failure mechanism and the load-carrying capacity with less than 4% deviation to the test. Thus, the enhanced level of assessment, using the proposed multi-level strategy, can be considered to be accurate, but the study also shows the importance of using guidelines for nonlinear FE analysis and bridge-specific information.     

大连国际会议中心复杂空间节点设计与有限元分析

当前新颖奇特、造型别致的现代建筑不断涌现,为实现这些建筑效果,往往需要设计复杂的空间结构方案,从而导致结构设计和节点设计的难度增大,尤其是复杂空间节点设计难度更大.如何设计形式各异的复杂空间节点,满足建筑和结构安全可靠,成为结构设计者必须解决的问题.本文就大连国际会议中心工程对复杂空间结构中出现的复杂空间节点的设计方法进行了论述,从结构优化设计的角度总结复杂节点的设计思路和方法,并对复杂节点进行有限元分析,以了解复杂空间节点的受力状态并验证复杂节点设计的安全可靠.     

索加强张拉膜结构的荷载分析方法

本从几何非线性有限元分析原理出发，推导了适合于索加强张拉膜结构荷载分析的非线性有限元公式，提出了一种解决膜单元皱折问题的简单、有效方法，编制了计算饥程序，从而完成了索加强张拉膜结构的荷载分析问题．最后以日本冲绳第75届博览会入口膜结构作为计算实例，得到了令人满意的结果。     

地基不均匀沉降引起上部钢结构损坏的非线性全过程分析

提出了一个综合结构变更定理,进行了地基不均匀沉降引起上部钢结构损坏的非线性全过程分析,能提供结构受损过程和加固后变化的详细信息,用于张家港东海粮油工业公司机械楼钢结构现状评价和加固设计,效果良好.     

渐进结构优化方法在结构动力优化中的应用

针对结构优化设计的重要性，介绍了一种求解带有频率约束的结构动力优化问题的渐进结构优化方法，并将优化结果与按照ESO方法所得结果做了对比，其结果基本一致。     

Mechanical properties of underpinning joints in structural moving: Experiments and numerical modeling

Underpinning is a key component in the structural moving process, especially for high‐rise buildings with gravitational loads. In this paper, a most commonly used 4‐sided wrapped underpinning joint with 2 underpinning beams and 2 coupling beams for the frame structures was investigated. Sixteen prototypes were tested considering different shear span‐to‐depth ratios, underpinning joint heights, reinforcement ratios, and so forth. The experimental results showed that the underpinning beams can fail in shear or flexure‐shear. The interface between the column and the beam is also prone to failure during the loading. Further, the bearing capacity can be greatly improved with decreasing of the shear span‐to‐depth ratio, whereas more damage may occur within the interface domain. In the numerical simulations, a damage–plasticity constitutive model was adopted, and the cohesive elements were used to model the old‐to‐new concrete interface between the column and beams. It was found that the numerical results agreed quite well with the experimental results. Thus, the proposed approach can be a useful basis for further analysis and optimized design of underpinning joints.     

钢筋混凝土非线性有限元分析概述

近年来,钢筋混凝土非线性有限元理论获得了重大的发展,与线弹性分析方法以及常规计算模型相比,非线性有限元方法具有适应性强、力学概念明确、分析精确等优点。因此对钢筋混凝土非线性有限元的研究进展和应用前景作了简要的述评。     

A concise introduction to the idealized structural unit method for nonlinear analysis of large plated structures and its application

The idealized structural unit method (ISUM) has now been widely recognized by researchers as an efficient and accurate methodology to perform nonlinear analysis of large plated structures such as ships, offshore platforms, box girder bridges or other steel structures. This paper presents a summary of pertinent ISUM theory and its application to nonlinear analysis of steel plated structures. Important concepts for development of various ISUM units which are needed to analyze nonlinear behavior of steel plated structures are described. Some application examples are shown, wherein comparisons of ISUM analysis predictions are made with numerical or experimental results for progressive collapse analysis of general types of steel plated structures and ship hulls, to illustrate the possible accuracy and versatility of the ISUM method. The use of ISUM for the analysis of internal collision/grounding mechanics of ships is also illustrated. This paper is in part an attempt to demystify ISUM and its applications for the benefit of a designer of steel plates structures (Paik and Thayambali, Ultimate limit state design of steel plated structures; 2002).     

A method for progressive structural crashworthiness analysis under collisions and grounding

Collisions and grounding always give rise to structural crashworthiness issues involving crushing, yielding, and fracture. For accidental limit state design and safety assessment associated with collisions and grounding, the resulting progressive structural crashworthiness characteristics should be analyzed to evaluate the energy absorption capability of the structure in the corresponding accidental event in conjunction with the associated criteria. The accidental energy absorption capability of a structure under collisions or grounding can be predicted by integrating the area below the reaction forces versus penetration curve until or after the accidental limit state is reached. For risk assessment associated with such accidents, the results of structural crashworthiness analysis are also used as a basis of the consequence analysis. The aim of the present paper is to present an efficient and accurate method which is useful for the progressive structural crashworthiness analysis of ships and ship-shaped offshore structures under collisions or grounding. Theoretical outline of the method is addressed. Application examples of the method to ship-shaped test structures are presented by a comparison with experimental results.     

正交各向异性冻土与建筑物相互作用的非线性有限元分析

将冻土与扩大墙基作为一个整体结构,将各向弹性模量及泊松比随温度、水分、应力变化的冻土视为正交各向异性的非线性材料;将冻土冻胀系数作为负线膨胀系数,按结构温度应力的计算方法,应用结构非线性分析的有限元法,对冻土与扩大墙基之间的相互作用进行数值计算,获得其应力场、位移场及冻土与扩大墙基之间的各种作用力;理论分析结果与模型试验吻合,提出了一种求解冻土与基础相互作用的通用数值分析方法,供生产设计参考应用。