钢框架加腋节点的应力分布与计算方法

用ANSYS软件对NIST/AISC研究项目中的UCSD模型进行受力分析,与试验结果进行对比,绘制关键部位的应力图,分析加腋区域的应力分布规律,给出钢框架加腋节点加腋区域应力的新的简化计算方法.     

加腋大板结构非线性有限元分析

加腋大板结构在地下室工程中应用较广,但目前有关加腋大板结构的计算分析及其设计方法尚未统一。为深入了解加腋大板结构的受力特性,文中以一个3×3跨加腋大板地下室顶板结构为研究对象,通过有限元软件Midas FEA NX,建立了加腋大板结构的三维实体及钢筋有限元模型,进行了非线性有限元分析。分析结果表明,加腋大板结构为典型的梁、板混合受力模式;加腋大板结构存在一定的拱效应,有利于对其裂缝的控制;加腋大板柱顶区域受力较为集中,设计应予以有效加强,梁端箍筋应力较大,设计时可按梁承担所有剪力考虑。采取有针对性的加强措施后,采用梁板有限元方法进行加腋大板结构的设计是经济合理且安全可靠的,有关计算及设计建议可为同类工程提供参考。     

加腋梁工程特性有限元参数分析

近年来随着加腋梁在工程中应用日趋广泛,对加腋梁的力学性能分析提出了要求。本文采用平面应力单元模拟加腋梁在承受均布荷载作用下的弹性变形和内力,通过60组模型给出了一系列加腋参数下加腋梁对应的内力和弹性变形,并对加腋后梁的弹性受力性能进行分析,给出了仅和加腋高比α、加腋长比β有关的支座弯矩系数、跨中位移系数的取值计算图表。     

钢框架梁柱节点加腋加固方法研究

针对梁柱连接节点梁上翼缘与柱翼缘没有焊接或焊接质量很差,在不破坏楼面混凝土板的情况下,提出梁下翼缘加腋方法进行加固形成梁柱刚性连接.采用有限元方法对分别采用三角形腋、矩形腋及组合腋加固的梁柱节点进行静力性能分析,比较了不同加腋方式节点的刚度、承载力和破坏模式.研究表明,加腋加固可以使节点达到刚性节点的要求,矩形腋加固效果最好.加腋节点的应力发展与常规刚性节点基本相同,不同腋节点的破坏模式不同,随着梁腋高度和长度的增加,加腋节点刚度、延性和承载能力均有提高,但增大幅度不同.梁腋高度越大,延性提高越多;随着梁腋长度的增加,节点刚度和承载能力提高越大.     

门式刚架加腋节点试验研究

对门式刚架梁柱螺栓端板竖放常规和新型圆弧形加腋2种连接节点进行了对比试验研究,其结果表明,加腋改造后节点要比常规节点刚度大、极限承载力高、延性好,可缓解节点域应力的过分集中.常规节点受力性能要比加腋节点差.     

浅谈地下室顶板加腋板施工技术

地下室顶板加腋板在主体结构施工过程时,往往因为是异性结构质量难以控制,加腋板区域钢筋过于集中,现场有一定的施工难度。文中分析了地下室顶板加腋板的原理和特点,介绍其具体施工流程,为在地下室顶板加腋板的施工提供一些参考意见。     

钢框架梁柱加腋节点有限元分析

通过建立钢框架节点试件的三维有限元分析模型,并对其进行非线性分析,对比地分析了各试件的应力分布规律,明确了腋在节点受力中的作用以及在循环荷载作用下,节点的滞回性能及加腋对节点吸能能力的影响。     

阶梯型管廊非一致地震激励下的减震措施研究

基于有限元分析方法,建立管廊-土体结构相互作用的三维有限元模型;通过模态分析,得到了3种不同接头形式阶梯型地下综合管廊的自振频率和变形特征,验证了模型的合理性;研究了阶梯型地下综合管廊在小震非一致激励条件下,平口、企口和现浇3种不同的管廊接头在设置加腋及加腋和减震层共同作用下的动力响应。结果表明：加腋使管廊廊身和接头的应力水平降低幅度在10%左右,使3种接头形式管廊顶板轴线应力均降低了50%～70%;加腋高度由300 mm增加到600 mm时,平口式管廊接头处应力降低幅度增加了1倍左右,而对于企口式和现浇式接头的影响较小;设置加腋和减震层共同作用的阶梯型多仓管廊应力水平降低幅度约为20%,而对顶板轴线的位移和接头处相对位移几乎无任何影响;设置加腋和减震层共同作用对不同接头形式的管廊第一、第三主应力降低幅度的影响不同,现浇接头的降低幅度约为30%,平口接头降低幅度约为20%,企口式接头降低幅度不足10%。     

高温下节点加腋前后应力响应非线性分析

采用有限元软件ANSYS/Workbench,建立钢结构加腋节点三维有限元模型,通过对比加腋节点和非加腋节点分别在外荷载、温度荷载、热力耦合3种情况下的应力分布规律以及各个方向应变分布,判断节点加腋前后受力的影响和变化。结果显示,在无温度场影响的情况下,加腋可以有效降低梁柱节点最大荷载,使下部节点处塑性铰外移。而在受火情况下,钢梁柱温度曲线呈梯度非线性变化,加腋钢框架升温速度要略慢于非加腋钢框架。施加外荷载时,腋的作用被削弱,上翼缘梁柱节点会比腋与下翼缘连接处更早产生塑性铰。     

加腋梁加腋板楼盖工程造价分析

文中分析了加腋尺寸对梁及板的材料用量及造价成本的影响,并对加腋梁、加腋板楼盖与单向板主次梁楼盖的工程造价进行了对比分析。分析结果表明,梁加腋长度采用4倍的梁加腋高度,即可保证经济性,与未加腋梁相比,其总造价降幅达19.8%;板加腋长度采用2倍的加腋高度,即可保证经济性,与未加腋板相比,其总造价降幅达17.3%。与单向板主次梁楼盖相比,加腋梁加腋板楼盖的单位面积所用设备造价降低幅度达21.2%,所用材料造价降低幅度达8.7%,材料和设备总造价降低幅度达10.4%。     

On the shear failure mode of granular column embedded unit cells subjected to static and cyclic shear loads

Since the initial conception of geosynthetic encased columns (GECs), exhaustion of column capacity due to vertical loads in bulging and punching failure modes were readily recognized. This lead to a vast majority of the available research on GECs to be about the behavior of columns under the action of vertical loads. Recently, two other likely and perhaps more dominant failure modes for granular columns namely, shear and bending failure modes, were identified. The purpose of this paper is to study the behavior of unit cells containing ordinary stone columns (OSCs) and GECs under static and cyclic lateral loads where shear failure of the column is imminent. 1-g physical tests are conducted with a novel apparatus, designated as Unit Cell Shear Device (UCSD), to model the behavior of the unit cells located close to the toe of an embankment where OSCs and GECs experience significant lateral loading. Overall failure envelope and strength parameters for GECs with varying reinforcement stiffnesses are quantified under static and cyclic lateral loading conditions. The distribution and magnitude of reinforcement strains in horizontal (hoop) and vertical direction of the columns are also considered.     

结构动力反应模拟试验系统的研制

介绍了在结构动力反应模拟试验系统的研制过程中遇到的结构技术难题以及相应的解决办法。其中包括结构自反力体系的概念设计、结构设计与计算、台体稳定分析、动力反应分析等。这一大型抗震试验系统由美国加州通局ＣＡＬＴＲＡＮＳ）、圣迭戈加利福尼亚大学（ＵＣＳＤ）和ＭＴＳ公司联合研制,将用于土木工程中阻尼器、隔震支座装置的足尺和实时动力试验。     

Use of FRP composites in civil structural applications

Fiber reinforced polymer (FRP) composites or advanced composite materials are very attractive for use in civil engineering applications due to their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance, light weight and potentially high durability. Their application is of most importance in the renewal of constructed facilities infrastructure such as buildings, bridges, pipelines, etc. Recently, their use has increased in the rehabilitation of concrete structures, mainly due to their tailorable performance characteristics, ease of application and low life cycle costs. These characteristics and the success of structural rehabilitation measures have led to the development of new lightweight structural concepts utilizing all FRP systems or new FRP/concrete composite systems. This paper presents an overview of the research and development of applications of advanced composites to civil infrastructure renewal at the University of California, San Diego (UCSD).     

Uncertainty and Sensitivity Analysis of Damage Identification Results Obtained Using Finite Element Model Updating

Abstract: A full‐scale seven‐story reinforced concrete shear wall building structure was tested on the UCSD‐NEES shake table in the period October 2005–January 2006. The shake table tests were designed so as to damage the building progressively through several historical seismic motions reproduced on the shake table. A sensitivity‐based finite element (FE) model updating method was used to identify damage in the building. The estimation uncertainty in the damage identification results was observed to be significant, which motivated the authors to perform, through numerical simulation, an uncertainty analysis on a set of damage identification results. This study investigates systematically the performance of FE model updating for damage identification. The damaged structure is simulated numerically through a change in stiffness in selected regions of a FE model of the shear wall test structure. The uncertainty of the identified damage (location and extent) due to variability of five input factors is quantified through analysis‐of‐variance (ANOVA) and meta‐modeling. These five input factors are: (1–3) level of uncertainty in the (identified) modal parameters of each of the first three longitudinal modes, (4) spatial density of measurements (number of sensors), and (5) mesh size in the FE model used in the FE model updating procedure (a type of modeling error). A full factorial design of experiments is considered for these five input factors. In addition to ANOVA and meta‐modeling, this study investigates the one‐at‐a‐time sensitivity analysis of the identified damage to the level of uncertainty in the identified modal parameters of the first three longitudinal modes. The results of this investigation demonstrate that the level of confidence in the damage identification results obtained through FE model updating, is a function of not only the level of uncertainty in the identified modal parameters, but also choices made in the design of experiments (e.g., spatial density of measurements) and modeling errors (e.g., mesh size). Therefore, the experiments can be designed so that the more influential input factors (to the total uncertainty/variability of the damage identification results) are set at optimum levels so as to yield more accurate damage identification results.     

论机会约束地下水随机管理模型

以地下水疏干管理模型为例 ,建立了机会约束地下水随机管理模型。分析了模型中有关变量的物理意义 ,并从理论和实践上分析了水文地质参数随机性对地下水管理模型结果的影响。     

廉租房“共有产权”模式研究

廉租房"共有产权"模式在中国尚处于探索阶段,本文主要研究这一模式能否解决地方政府配套资金不足问题,促进廉租房的建设并在全国范围内推广。分析了廉租房"共有产权"模式的起源,对目前实行该模式的各省份政策进行了比较,对该模式的缺陷进行了分析,最后得出"共有产权"模式不适宜推广的结论。     

价值工程在通风管道设计中的应用

利用价值工程的有关原理建立了通风管道评价新模型 ,并对该模型进行了分析与评价 ,同时通过工程实例验证了模型的有效性 .运用该模型对几种通风管道进行了分析评价 ,为通风空调工程的优化设计提供依据 ,为通风管道发展指出了方向 .     

对新型建筑给水塑料管材的价值工程评价

利用价值工程的有关原理 ,建立了新型建筑给水塑料管材评价模型 ,并对该模型进行了分析与评价 ,通过工程实例验证了此模型的有效性 .运用该模型对这些塑料管材进行了分析评价 ,为建筑给水工程优化设计提供了依据 ,并指出了新型建筑给水塑料管材的发展方向 .     

供水管网系统不确定性分析的理论与发展

为了分析城市给水管网系统模型的不确定性,介绍了多种不确定性分析理论的应用与发展。从管网系统的复杂性入手,分析了管网系统不确定性产生的原因,从模型参数和模型结构两方面分析了管网系统模型的不确定性。介绍了GLUE、BaRE、MCMC和FOSM等不确定性分析方法的理论与进展,认为模型的不确定性分析是模型开发中必不可少的程序。