变刚度框架－剪力墙－薄壁筒斜交结构考虑部分楼板变形分析的广义框架法

本文将沿高度方向截面变化、平面布置复杂、需要考虑部分楼板变形的框架剪力墙薄壁筒高层建筑结构体系．划分为楼板刚性部分和楼板变形部分，楼板刚性部分用连续化方法处理以后，视为广义空间薄壁剪－弯柱，变形楼板视为水平放置的深梁，整个结构视为广义框架，然后用矩阵位移法分析。本文介绍的方法计算简便，具有广泛的适用性。     

变截面框架-剪力墙-薄壁筒斜交结构考虑楼板变形时的计算

本文用沿高度方向分段连续化的方法,对沿高度方向为阶形变截面,在平面内布置复杂、需要部分考虑楼板变形的框架剪力墙薄壁筒结构,建立了在水平荷载作用下的弯扭耦连方程组。通过常微分方程求解器求解其位移和内力。为复杂结构提供了一种可供设计用的简化算法。     

铝合金薄壁框架件加工变形的应力分布研究

7075航空铝合金薄壁框架件加工变形的预测是构件形变控制领域的技术难题,掌握铝合金薄壁框架件上的加工应力分布对预测构件变形有着重要的作用.本文运用弹性力学理论,在实验基础上,利用层削法和X射线衍射应力测试技术,建立了薄壁框架件的应力与弯曲变形的力学模型.模型反映了加工应力和初始应力对构件实际变形的影响机制,在此基础上,再通过数学解析方法,以这两种应力场分布为主变量,构建了薄壁框架构件应力与变形的函数,完成了对构件最大变形挠度的计算.通过比较实验所测构件变形值与计算得到的变形结果发现:构件实际测量最大变形量基本处于数学解析函数计算变形区间内,数据偏差在20~50μm.研究结果表明:在已知初始应力、结构尺寸、加工参数条件下,解析函数能有效地预测出薄壁框架件加工后的变形,可为薄壁构件加工变形控制提供工艺指导.     

薄壁扁球壳结构在撞击载荷下的变形控制方法研究

对薄壁扁球壳结构撞击刚性板的变形特性和控制方法进行了研究。使用LS—DYNA软件建立了薄壁扁球壳结构撞击刚性板的有限元模型，并通过试验结果对模型的有效性进行了验证。利用数值仿真方法，对薄壁球壳结构撞击刚性板的变形特性和动态响应特点进行了分析。针对薄壁扁球壳结构一种典型撞击性能的要求，利用变形控制和局部弱化等方法得到了符合要求的变形模式和加速度响应曲线。最后的试验结果验证了设计结构方案的正确性．该变形控制方法可应用于工程实际。     

N段变截面高层建筑框架-剪力墙结构考虑楼板和地基变形时的整体稳定分析

本文为需要考虑楼板变形和基础、地基共同工作的变截面高层建筑框架-剪力墙结构的整体稳定问题提供一个简单的算法。将框-剪结构沿高度方向分段连续化,考虑楼板变形,建立其整体稳定题问的微分方程组。基础置于弹性地基或按弹性地基梁考虑的桩基上。根据上、下部的平衡和协调条件,用常微分方程求解器求解其临界荷载和相应的失稳形态。编制了变截面高层建筑框架-剪力墙结构考虑楼板和地基变形时的整体稳定分析的通用程序——OSATBS,便于工程设计人员直接采用。最后给出了计算示例。     

减小薄壁套加工变形的工艺分析

本文通过对薄壁套加工难点的剖析，指出其所具有的刚性差、装夹困难、易变形等缺陷，并对影响薄壁套变形的原因进行了分析，从装夹力、热变形及振动的分析及改进薄壁套加工方法等不同角度入手，寻求减小薄壁套加工变形的措施和途径，为问类产品及同行们提供可借鉴的工艺途径和分析问题的思路。     

竖向荷载下半刚接组合框架的有限元分析

为了分析连接弯矩-转角关系和荷载大小对组合框架性能的影响,该文采用有限元方法,考虑了连接弯矩-转角关系、楼板的组合效应和几何非线性的影响,通过引入能直观反映连接刚度的端部约束系数来修正现有刚接框架的结构刚度矩阵和杆件固端力。研究表明:连接弯矩-转角关系对框架内力和位移影响较明显;在半刚接阶段0.143相似文献   

高层建筑结构分析程序的新策略

本文探讨了用面向对象的方法建立高层建筑结构分析有限元程序的策略，并在此基础上实现了一个新的结构分析计算程序，这个程序可以有效处理高层建筑结构设计中常用的结构形式以及与它们相适应的计算形式，例如，真三维模型，带（部分）刚性楼板的三维模型，糖葫芦串模型以及层间剪切模型。     

高层建筑框支剪力墙结构自振特性计算的超元法

本文提出高层建筑框支剪力墙结构自振特性计算的超元法，即将上部剪力墙和落地剪力墙视为等效柱，底部框架视为等代柱，楼板视为深梁，整个结构简化为固定在地面上的十字交叉梁系，采用超级单元刚度矩阵组合、凝聚得到结构的整体侧移刚度矩阵，进行结构的自振特性计算。例例表明，本法计算简便省时，结果可靠。     

喷砂强化对铝合金薄壁框架件形状的影响及应用

铝合金薄壁框架件铣削加工后会有不同程度的变形,表面喷砂强化既可以提高构件的机械性能,也可以对铣削加工后构件的变形进行矫正,这对构件的变形控制和形状稳定性都具有积极作用.本文针对薄壁件形状特点(壁厚2 mm),分别对构件底部和薄壁进行喷砂处理,并通过X-ray表面应力测试、表面硬度和变形测试,对喷砂后构件的变形状况进行分析.研究发现,改变喷砂粒度、空气压力和表面全喷覆次数,对材料表面应力进行调节,可使铣削加工后构件的变形得以调整,一定条件下,其变形矫直率达85%以上.分析认为,薄壁件形状特点与初始内应力水平使得表面应力在薄壁框架件变形中发挥了主要作用.因而,可以在不同位置采用差异化喷砂工艺,对材料表面应力分布进行针对性调节,使喷砂件的形变达到预期要求,最终通过喷砂表面强化实现对薄壁构件变形的调控.     

斜交多肋T梁桥空间计算的有限单元法

将斜交多肋T梁桥的桥面板视为斜形板梁,肋板视为普通板梁,并在构造其位移模式时考虑了T梁桥面板剪滞效应和局部弯曲的影响,然后根据斜交多肋T梁截面位移参数的变形协调关系来组拼其单元刚度矩阵,由此提出了斜交多肋T梁桥空间计算的斜形板梁有限单元法。     

Analysis of short fibres orientation in steel fibre-reinforced concrete (SFRC) by X-ray tomography

The mechanical properties of fibre composite materials are largely determined by the orientation of fibres within the matrix. Which orientation distribution short fibres follow in different parts of a structural element is still a subject for research and discussions in the scientific community. In this article, we present a modern and advanced method for measuring the orientation of short fibres in steel fibre-reinforced concrete (SFRC) by X-ray microtomography. With this method, a voxel image of the fibres is obtained directly in 3D, and the orientation of each individual fibre is calculated based on a skeletonized representation of this image. Scans of 12 SFRC samples, taken from the central height region of real-size floor slabs, reveal the fibres to be mostly horizontally oriented near the centre of a floor slab and more vertically oriented near the edge; here the alignment with the formwork dominates. The fibre orientation distributions are characterized by several orientation parameters as quantitative measures for the alignment. On the practical side, this method has the potential to be incorporated into the development and production process of SFRC structures to verify how the fibres contribute to capacity.     

Introduction to a new series of thin-wall prestressed concrete structures developed in China

This paper presents a new series of thin-walled pre-stressed concrete roof and floor slabs. For roof structures, an innovative thin-walled slab with a larger span, called the wild-goose-shaped slab, has been developed and used in China since 1979. Its use has spread into 5 provinces, especially over the past 5 years. A roof constructed with this slab is more economical than a traditional concrete structure; the speed of hoisting will greatly accelerate construction as one piece of this slab can cover a large area. Use of the wild-goose-shaped slab as roofing and the thin-walled single-T slab as flooring will allow the construction of multistory buildings. Many two-story buildings have been completed using this combination. The maximum span of the wild-goose-shaped roof slab attains 36 m and that of the single-T floor slab 30 m. The new roof slab can be used in civil structures or industrial plants with or without the use of overhead cranes. As of March 1995, the gross architectural area completed with these slabs was more than 400,000 m², within 144 engineering projects. The design, construction and testing of these new roof slabs are briefly described in this paper.     

On the interaction between a generalized screw dislocation and circular-arc interfacial rigid lines in magnetoelectroelastic solids

The interaction of a generalized screw dislocation, which is located inside either the inclusion or the matrix, with circular-arc interfacial rigid lines under remote antiplane shear stresses, in-plane electric and magnetic loads in linear magnetoelectroelastic materials is dealt with. By using the complex variable method, the general solutions of the physical problem are presented in this paper. The closed-form solutions for stresses, electric displacement fields and magnetic induction fields are derived explicitly for the interface with a finite rigid line. The image forces acting on the generalized screw dislocation are then calculated by using the generalized Peach–Koehler formula. The influence of the length and the location of the rigid line as well as the material mismatch on the image force is evaluated. Numerical computations and discussions show that, when the length or the position of the interfacial rigid line achieves a critical value, the image force on the dislocation changes its direction due to the existence of the rigid line. In addition, the soft inclusion can repel the dislocation in magnetoelectroelastic materials owing to their intrinsic magnetoelectromechanical coupling behavior.     

Optimization Design of RC Ribbed Floor System Using Eagle Strategy with Particle Swarm Optimization

The eagle strategy algorithm is combined with particle swarm optimization in this paper. The new algorithm, denoted as the ES-PSO, is implemented by interfacing Etabs structural analysis codes. ES-PSO is used to optimize the RC ribbed floor system, including floor and underground garage roof. By considering the effects of reinforcement, the principle of virtual work is applied to calculate the deflections of components. Construction cost is taken as the objective function and the constraint conditions are required to satisfy. Accordingly, the optimal layout, the optimal sections of the beams and slabs and the corresponding reinforcements are obtained for different column grids. In this investigation, the RC ribbed floor system is optimized according to the Chinese standard, whose column grids are 8.4 m and 8.4 m. The performance of the ES-PSO algorithm is good enough, which can be applied to practical engineering. The paper can also provide a basis for subsequent optimization design of monolithic structures.     

Green's First Identity Method for Boundary-Only Solution of Self-Weight in BEM Formulation for Thick Slabs

The present paper develops a new technique for treatment of self-weight for building slabs in the boundary element method (BEM). Due to the use of BEM in the analysis, all defined variables are presented on the slab boundary (mesh is defined only along the slab boundary). Self-weight, however, is usually defined over slab domain, hence domain discretisation is required, which spoils the main advantage of the BEM. In this paper a new method is presented to transform self-weight domain integrals to the boundary for such slabs. The proposed method is based on using the so-called Green's first identity. All new kernels for generalized displacements, stress-resultants, and tractions are derived and listed explicitly. The present formulation is implemented into computer code and several examples are tested. Results are compared against results obtained from other numerical method to prove the accuracy and validity of the present formulation.     

结构倒塌时楼板碰撞效应的简化评估方法

针对上楼板、下楼板碰撞的两种极限状态 —— 完全塑性碰撞和完全刚性碰撞,开展了碰撞过程中动能转移量的理论分析,考察了上板、下板质量比对动能转移量的影响,同时进行了2种极限状态下动能转移量的数值计算;提出了结构倒塌时上板、下板碰撞效应的一种简化评估方法,具体包括2个步骤:1) 下板的非线性静力分析;2) 采用能量平衡原理估算上板的最大允许重力荷载。研究表明:上板、下板质量比等于1时,完全塑性碰撞后的总动能转移百分比和下板动能转移百分比分别为33.3%和16.7%;完全刚性碰撞后的下板动能转移百分比与碰撞前上板速度、碰撞后上板周边反弹速度等参数有关,上板、下板质量比等于1时下板动能转移百分比为44.4%~97.1%;采用通用软件ABAQUS计算得到的两种极限状态对应的下板动能转移百分比,总体上与理论分析结果较为接近。     

钢筋混凝土框架抗连续倒塌的压拱机制分析模型

钢筋混凝土框架结构依靠梁板组成的楼盖系统来抵抗连续倒塌,其在小变形下的连续倒塌抗力由梁板内的压拱机制提供。现有压拱机制的宏观理论分析模型参数过多且不能考虑楼板的影响,因此难以在工程设计中进行应用。该文基于楼盖系统微观受力机理的分析,建立了压拱机制下梁板子结构系统的连续倒塌抗力分析模型。和现有模型相比,该文计算模型的参数大幅减少、公式显著简化,且能够考虑楼板和梁抵抗连续倒塌的共同作用。通过与国内外47个梁试件和6个梁板子结构试件的试验结果进行对比,发现该文计算模型在计算梁试件时计算精度和现有模型精度相同,而在计算梁板共同作用下的连续倒塌抗力时精度提高显著,能够为混凝土框架结构的抗连续倒塌工程设计提供参考。     

Connections for composite concrete slab and LVL flooring systems

Composite concrete slab and timber flooring systems are commonly used in many parts of the world to exploit the high strength-to-weight ratio of timber and the good acoustic separation provided by concrete floor slabs. This paper describes the results of an experimental programme that investigated the suitability of a range of connectors to transfer shear between a concrete slab and a laminated veneer lumber (LVL) beam. Shear tests on reduced scale specimens were performed with the aim of comparing the strength, stiffness, and post-peak performance of different connectors such as round and rectangular concrete plugs with and without screw and steel pipe reinforcement, proprietary (SFS) screws, coach screws with different diameters, sheet brace anchors, and framing brackets. The rectangular concrete plug reinforced with a coach screw was found to provide the greatest stiffness and strength, as well as favourable post-peak behaviour. Such a system can be used for cost-effective composite floor systems due to its efficient cost-to-capacity ratio, which reduces the number of connectors needed along the beam axis to achieve the composite action.