柱脚刚接与铰接柱列支撑体系受力性能对比研究

为研究柱脚刚接与柱脚铰接柱列支撑体系的不同受力性能,采用蒙特卡罗方法,考虑柱子和水平撑杆初始几何缺陷的随机遇合,应用有限元程序ANSYS对柱脚刚接和柱脚铰接柱列支撑体系进行大量参数仿真分析。研究结果表明:柱脚刚接柱列支撑体系失稳时柱子呈两个半波的变化趋势,柱脚铰接柱列支撑体系失稳时柱子呈三个半波的变化趋势,因而后者的极限承载力和柱中撑杆内力均大于前者,且后者较高的极限承载力更大幅度地增加了柱中撑杆内力;柱子和水平撑杆初始几何缺陷的随机遇合作用导致柱中水平撑杆受压或拉力的随机性,降低了支撑内力,比GB 50017—2003《钢结构设计规范》中柱列支撑设计公式计算的支撑内力小许多。     

双层纵向柱列支撑的设计要求

支撑体系的作用是保证柱列的几何不变性和减少柱子计算长度。本文从柱列整体稳定性出发,对双层纵向支撑体系的强度和刚度设计要求进行了研究,分别得到了横系杆完全刚性、交叉支撑完全刚性以及支撑构件有限刚度情况下,对支撑的门槛刚度要求;考虑实际柱列的初始缺陷,确定最不利初始缺陷组合情况下,使柱列极限承载力达到计算长度减半的欧拉荷载所需要的支撑的强度设计要求。     

柱顶受轴力的柱列支撑受力分析

采用蒙特卡罗方法,考虑柱子初始缺陷和撑杆初始缺陷的随机遇合问题,应用有限元程序ANSYS对柱顶受轴力的柱列支撑体系进行了大量的仿真分析,得到了柱列纵向支撑体系的两种失稳模式;通过概率统计得到柱中水平撑杆所受内力的双正态概率密度函数,据此确定了可用于实际工程设计的支撑力的大小。结果表明:当柱顶轴力相等时,采用《钢结构设计规范》(GB 50017—2003)中柱列支撑设计公式计算支撑力偏大;当柱顶轴力不等时,采用规范公式计算支撑力将更保守;柱子初始缺陷和撑杆初始缺陷的随机遇合作用导致柱中水平撑杆受压力或拉力的随机性,降低了支撑力。     

竖向荷载下纵向柱列交叉支撑刚度要求

从保证柱列纵向稳定性的角度,对竖向荷载作用下交叉支撑的刚度要求进行研究.介绍无初始几何缺陷的单、双层纵向柱列支撑体系的抗侧刚度要求;根据实际框架中的各种初始几何缺陷,考虑竖向荷载的P-△与P-δ二阶效应,利用有限元程序ANSYS对承受竖向荷载作用的单、双层纵向柱列支撑体系进行受力分析,据此确定用于设计的竖向荷载作用下单...     

设中间交叉支撑的110kV变电构架设计分析

为了改进传统变电构架的结构型式,设计了一种新型交叉支撑变电构架,将传统构架两端端撑合成为一个交叉结构,设置于构架中部,减少占地面积。采用结构拓扑优化中的密度法优化支撑布置型式,基于优化后的构架型式,建立有限元模型,优选构架梁和构架柱的截面型号。对该构架进行有限元分析,计算其强度和刚度。结果表明设中间交叉支撑的变电构架安全可靠,满足国家及行业现行相关技术标准要求,可为同类结构设计提供参考。     

竖向荷载作用下厂房纵向支撑的受力分析

从保证厂房柱列纵向稳定性的角度,对柱顶撑杆的设计要求进行了研究。采用蒙特卡罗方法,考虑实际工程中柱子和柱顶撑杆初始缺陷的随机遇合,应用有限元程序ANSYS对承受竖向荷载作用的柱列纵向支撑体系进行了大量的仿真分析,得到了柱列纵向支撑体系的三种失稳模式;通过概率统计得到柱顶撑杆所受内力的三峰正态概率密度函数,发现柱子和撑杆初始缺陷的随机遇合作用导致柱顶撑杆受压、拉或零受力的随机性,降低了支撑力,据此确定了可用于实际工程设计的支撑力的大小,为传统的柱顶撑杆由纵向受力决定的设计方法补充了竖向受力分析的验算方法。     

竖向荷载作用下柱列支撑体系受力性能试验研究及有限元分析

为研究柱列支撑体系的受力性能和验证有限元方法分析该问题的可靠性,对带有不同初始几何缺陷分布的单层和双层柱列支撑体系进行静力模型试验研究。研究结果表明:由于试验模型中柱和水平撑杆的初始几何缺陷的随机分布,水平撑杆受压力或拉力也是随机的;双层柱列支撑体系的极限承载力高于单层柱列支撑体系的极限承载力,且双层柱列支撑体系中的水平撑杆减小柱的计算长度超过柱高的一半;柱列支撑体系的失稳破坏是由于单柱失稳破坏引发的。采用有限元模型对试验进行了模拟验证,计算结果与试验结果吻合良好。     

柱脚刚接与铰接柱列支撑体系受力性能试验研究与有限元分析

为研究柱脚刚接与柱脚铰接柱列支撑体系的不同受力性能和验证有限元方法分析该问题的可靠性，对带有不同初始几何缺陷分布的柱脚刚接与铰接柱列支撑体系进行了静力模型试验研究。研究结果表明：柱脚铰接柱列支撑体系的极限荷载和柱中水平撑杆内力均高于柱脚刚接柱列支撑体系,且前者较高的极限荷载更大幅度地增加了柱中水平撑杆内力；由于试验模型中柱和水平撑杆的初始几何缺陷的随机分布，柱中水平撑杆受压力或拉力的情况是随机的；柱列支撑体系的失稳破坏是由于单柱失稳破坏引发的。采用有限元模型对试验进行了模拟验证，计算结果与试验结果吻合良好。     

在竖向荷载作用下框架结构内力计算的独立柱法

为了方便、快捷、精确地手算框架结构在竖向荷载作用下的内力,将框架结构按柱分解为若干个独立的柱子,与柱子相连的横梁视作约束弯矩,导出独立柱位移的计算公式,运用追赶法计算每根柱子的内力和位移;与此同时,与柱子相连的梁的另一端弯矩,也可计算出来作为相邻柱子的附加外荷载,每个柱子分别独立计算.通过两轮计算,可得到令人满意的计算精度.     

装配式槽钢骨架轻质混凝土剪力墙抗震性能 试验研究及有限元分析

为研究装配式槽钢骨架轻质混凝土剪力墙抗震性能,对装配式槽钢骨架轻质混凝土剪力墙试件进行低周反复试验,分析了试件的破坏特征、滞回曲线、骨架曲线、刚度退化以及耗能能力。利用Abaqus有限元分析软件建立试件数值模型,模拟结果与试验吻合较好。在此基础上,研究暗柱数量、X形暗支撑对型钢骨架轻质混凝土剪力墙承载能力以及延性性能的影响。分析结果表明:设置3、2根暗柱试件的极限水平承载力相对于1根暗柱试件分别提高25.9%、8.3%,延性分别降低37.3%、17.3%;设置X形暗支撑试件的极限水平承载力、延性相对于无X形暗支撑试件分别提高46.9%、66.7%,屈强比减小,说明X形暗支撑能够更加有效改善结构的抗震性能。     

轴力对巨型钢柱滞回性能的影响分析

通过双重非线性有限元程序ANSYS5.7,分析了不同轴压比对人字形支撑和X形支撑的两种巨型钢柱滞回性能的影响规律。并针对地震作用下实际结构中巨型柱可能出现的受力状态,讨论了轴力和水平剪力同时增加或减小时巨型钢柱的滞回特性。     

支撑布置对钢框架结构抗侧刚度的影响

纯钢框架建筑结构体系刚度较小,层间位移起主要控制作用,设置支撑体系可有效地提高结构的整体抗侧刚度,减少结构用钢量。以广泛应用的多高层钢框架支撑结构为对象,通过计算不同支撑类型及支撑布置方式下钢框架支撑结构的顶点位移,研究了支撑形式对多、高层钢框架结构抗侧刚度的影响。研究结果表明,对于不同的支撑类型,支撑沿竖向集中布置于中间跨的钢框架结构抗侧移刚度好于将支撑布置在边跨以及其他跨上。对于相同的支撑布置方式,不论是中心支撑,还是偏心支撑,在抗侧刚度和经济性方面,人字形支撑框架均好于单斜杆支撑框架。     

The use of single diagonal bracing in improvement of the lateral response of tall buildings

The improvement of the lateral response of tall buildings is a subject of great concern both in high wind areas and seismic regions. The lateral deflection of a tall building subjected to lateral loads can be decomposed into shear and bending components. Properly oriented single diagonal bracings are introduced in order to bring advantageous interactions between these two modes of deflection resulting in a reduction of the overall lateral deflection of the frame. The deflection of a panel with a single diagonal, when subjected to vertical downward load, has a lateral component caused by the axial force developed in the single brace, which, due to asymmetry, results in the lateral deflection. In order to restrict the panel from lateral deflection a compensating lateral force is required. By locating the single diagonal bracings in an improved manner, the vertical tension and compression on the opposite sides of the frame caused by the bending effect automatically generate the above mentioned lateral compensating force which opposes the inter story drift. A simple truss model is introduced to study the relationship between the vertical loading and the lateral load required to retain the vertical alignment of a panel with a single diagonal. This relation is then studied in detail and the optimal values of the height-to-width and brace-to-column stiffness ratios, needed to produce the maximum equilibrating lateral force are computed. Further, the single diagonal bracings are applied to typical building frames. Results from elastic analyses are compared with that of the conventional X-braced frame. Pilot analysis shows a reduction of about 2% in the lateral deflection of a typical 24 story braced frame building with rigid connections and five bays using the proposed bracing scheme.     

单层房屋钢支撑体系的内力和杆件计算

单层房屋钢支撑体系的设计,长期以来只考虑风力和吊车制动力。实际上支撑杆件因被撑构件的几何缺陷而承受支撑力,十字交叉斜撑又因被撑构件的压缩变形而产生附加压力。指出这两种内力不应被忽视,并给出了有关计算公式。对设计中如何计算屋架上弦横向支撑和柱间支撑提出了建议,指出吊车梁下的交叉支撑不应作为拉杆看待。     

Performance evaluation and strengthening of concrete structures with composite bracing members

Steel bracings, in different geometrical forms, are commonly used in steel and concrete structures. The lateral stiffness of structures with concentric bracings depends on the buckling capacity of compressive bracings; in turn, this buckling phenomenon leads to a decrease in the energy dissipation capacity. Composite bracings, composed of steel cores encased in concrete, can increase their capacities. In this paper, the behavior of composite bracings is studied in two parts. At first, a number of braced frames are selected and their behaviors under cyclic loading are studied. Then, using the data obtained from the first part, two existing concrete structures, a three story and a nine story building, are selected and strengthened against seismic loadings by both the conventional concentric steel and the latter composite bracing systems. The behaviors of these structures are then studied by the push-over method and the results for the two types of bracings are compared.     

Behaviour of frames with Non-Buckling bracings under earthquake loading

The energy dissipation capacity of conventional concentric braced frames in multi-storeyed buildings degrades drastically under earthquake loading, due to buckling of bracings under the compression regime. Non-Buckling bracing is an innovative patented system, in which the buckling of the bracing is prevented and the energy is dissipated by plastic deformation under tension-compression cycles, with stable hysteresis. The strength and stiffness of Non-Buckling bracing can be tailored to obtain the desired level of storey drift limit and energy absorption. A single-bay ten-storey concentric braced frame with diagonal Non-Buckling bracing is chosen for studying their effect during earthquake loadings. Non-linear time history analysis was carried out using SAP2000 to study the variation of maximum base shear, roof displacement, inter-storey drift, Damage Index and stresses in various members due to the El Centro earthquake accelerogram. It is observed that Non-Buckling bracings are effective in dissipating energy and controlling inter-storey drift.     

Effect of mid-connection detail on the behavior of x-bracing systems

In this paper, the effect of mid-connection detail of x-bracings comprised of build-up sections on the elastic-plastic behavior of braced systems is investigated. Then, a proposed symmetric mid-connection detail is compared with the commonly used one, analytically. In common mid-connection detail for build-up sections, one diagonal member (which is comprised of a pair of channels or angles) is usually discontinuous at the mid-connection and the other continuously passes through the connection. A rectangular gusset plate is used to join the discontinuous and continuous diagonals in practice. In the proposed method, one section from each diagonal member is discontinuous and the other is continuous. Buckling and post-buckling behavior of single span and single story models of cross-braced systems have been verified during a nonlinear static finite element analysis. The results show that the proposed mid-connection detail can improve both strength and ductility of cross-braced systems. Also, it is shown that adding two cover plates on both sides of discontinuous diagonal members in common mid-connection detail can partially improve the overall behavior of the system.     

某偏心支撑框架结构设计

偏心支撑框架在弹性阶段的刚度接近中心支撑框架,弹塑性阶段的延性和耗能能力接近延性框架,是一种新型的高层钢结构抗震体系。以咸阳丽彩.天玺广场商住楼工程为例,详细介绍偏心支撑框架的耗能梁段、非耗能梁段、支撑和柱的设计以及构造措施,有助于工程设计人员更好地了解该结构体系设计过程,可为类似工程设计提供参考。