低周反复荷载作用下钢梁的性能

前言在地震区的工业厂房柱列之间,如果在交叉支撑中部设置消能内框(如图1所示),在地震过程中使内框产生一定的塑性变形,则将消耗由地震引起的部分能量,提高柱间支撑的阻尼比,减小地震力,而且可以增大结构的延性,提高厂房的纵向抗震性能。消能支撑在低周反复荷载作用下的试验说明,内框杆件的塑性变形发挥越充分,消能支撑的滞回特性就越好。对处于弯矩、剪力和轴力共同反复作用下的消能支撑内框杆件的刚度和强度目前尚无计算方法可以借鉴;为了研究这些问题,我们进行了2根槽钢模拟梁、5个钢筋混凝土榧消能支撑内框杆件和4个钢柱框消能支撑内框杆件在低周反复荷载作用下的试验,并结合国外有关的试验论述,对钢梁的弯矩—曲率关系、挠度延性系数、阻尼比以及极限强度进行了分析研究,为内框杆件     

钢框架消能减震体系研究与工程应用

对上海地区的一幢7层钢结构办公楼采用普通支撑和消能减震支撑两种抗侧力体系,在7度地震作 用下的抗震性能进行对比分析。消能减震支撑由钢支撑、粘滞阻尼器和橡胶支座组成。计算结果表明当两种 抗侧力体系对位移控制效果接近的情况下,普通支撑体系增加了刚度,同时也增加结构的层间剪力、与支撑相 连柱的轴力,而消能支撑体系能有效减少这些结构内力,故比前者大大提高了主体结构的抗震性能。同时试 验也表明所选阻尼器性能良好。     

北京泰康大厦钢结构设计

北京泰康大厦为高烈度地震区的超高层建筑。综合考虑建筑形体、功能与布置以及结构抗震要求,主体结构采用双重抗侧力体系钢框架-支撑筒体结构。塔楼外围为钢框架结构,中间核心筒采用带消能梁段的偏心支撑筒体,整体结构具有质量轻、地震作用小、抗震性能优越等优点。整体结构分析表明,结构各项整体指标均满足规范要求。对带消能梁段的偏心支撑筒体、外框斜柱、角部大悬挑楼盖结构以及地下室矩形钢管混凝土柱剪力墙筒体等关键结构构件进行了深入分析,提出了合理的应对措施和设计构造。     

竹框架结构的小型振动台试验研究

通过一个缩尺比为1∶10的单层单跨框架结构模型的小型振动台试验,研究了竹框架结构中梁、柱连接方式及柱间支撑对其抗震性能的影响,试验结果显示,梁柱连接节点采用榫卯方式增加了框架的刚度,设置柱间支撑可消能减震,设置支撑的方式对提高结构抗震性能更有效。     

大跨度双层吊车钢结构厂房的柱间支撑设计

文章以某大型模锻车间大跨度双层吊车钢结构厂房的柱间支撑布置为例,阐述了此类型厂房柱间支撑的布置原则及内力计算方法,分析得出在低烈度地区风荷载与吊车荷载的组合对柱间支撑的设计起到控制作用;实践证明大跨度大吨位吊车厂房柱间支撑采用槽钢组成的双片支撑经济适用。     

重庆某超高层结构选型及抗震设计

重庆某超高层塔楼结构高度219.50m,根据其结构特点进行了结构方案的对比分析,最终采用矩形钢管混凝土柱-钢梁-钢筋混凝土核心筒结构体系;同时,为满足刚重比及层间位移角要求,根据建筑平面布置的条件采用了周边环带桁架作为其结构加强层;周边桁架腹杆采用屈曲约束支撑,以达到消能减震的作用。分析表明,经过合理设计的带加强层的矩形钢管混凝土柱-钢梁-钢筋混凝土核心筒结构可以满足预定的使用功能,可以达到经济合理、安全可靠的目标。     

钢筋混凝土柱在弯剪扭耦合作用下的试验研究

为了研究钢筋混凝土柱在双向受力及扭转耦合作用下抗震性能,采用矩形、菱形、椭圆形的位移加载模式分别对3个钢筋混凝土柱进行了拟静力试验.根据试验结果对试件的滞回曲线,恢复力特性、累积滞回耗能及损伤特性进行了分析.     

单层工业厂房柱间支撑的计算和合理设置(文摘)

一、柱间支撑的计算李平安等对柱间支撑进行了试验研究,得出以下主要结果: 1.柱间支撑计算简图对于交叉的钢柱间支撑可以将柱、柱顶连系杆、吊车梁及钢支撑作为柱间支撑系统,按铰接二次超静定结构计     

偏心支撑框架的设计计算方法

我国《建筑抗震设计规范》(GB5 0 0 11- 2 0 0 1)规定 ,8度以上宜采用偏心支撑 ,但我国至今没有一个自行设计的工程用过这种支撑。参考美国计算例题、相关规范 ,并依据我国规范 ,对偏心支撑框架的实际计算方法进行讨论 ,总结出适合我国规范和实际情况的偏心支撑框架设计计算方法。其中 ,重点介绍了各杆件的内力计算、消能梁段的设计、非消能梁段的设计、支撑的设计、柱的设计等 ,给工程设计提供理论基础和实用方法 ,有助于设计人员对该体系设计过程的了解和此种支撑的推广应用     

单跨无洞框支密肋壁板结构墙梁中托梁内力系数分析

考虑托梁高跨比、墙体高跨比、底部框架柱的截面高度与其长度之比诸因素,采用正交试验设计,通过对单跨无洞框支密肋壁板结构墙梁有限元计算结果的直观分析和方差分析,对其托梁内力的影响因素进行了显著性分析,并在此基础上利用回归分析得到了考虑墙梁组合作用的托梁内力系数。     

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.     

交叉支撑位置对被支撑柱数量的影响

工业厂房的支撑体系通常由交叉支撑和水平撑杆组成,当交叉支撑设置于柱列一端时,被支撑柱子的数量不宜超过8根。文中考虑柱子初始弯曲的随机性,应用有限元程序ANSYS对交叉支撑设置在柱列一端、柱列中间和柱列两端三种情况下的柱列支撑体系进行了大量的有限元参数分析。研究结果表明,当交叉支撑分别设置在柱列中间和柱列两端时,被支撑柱子的数量可分别增加至14和15根,说明可根据交叉支撑位置合理确定被支撑柱的数量,达到即安全又经济的目的。     

Prevention of story drift amplification in a 20‐story steel frame structure by tension‐rod displacement–restraint bracing

This paper proposes an application of tension‐rod displacement–restraint bracing to prevent story drift amplification in tall steel moment frames. Seismic response analyses of a 20‐story bare steel frame are performed first, revealing that story drift amplification occurs in the upper and lower stories at different times. Characteristics observed for the seismic response of the bare frame suggest the efficacy of the delay action of bracing. Subsequently, seismic response analyses of the 20‐story braced frame with tension‐rod displacement–restraint bracings reveals that the increment of the column axial force by addition of bracing is reduced dramatically by the delay action of bracing. The story rotation angles within partial stories where the story drift amplification occurs in the bare frame are also reduced efficiently by the displacement–restraint bracing. The delay action of bracing influences the floor response acceleration and the residual displacement. Finally, parametric analysis results indicate an appropriate value of the story rotation angle at which the brace action starts.     

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。     

Assessment of eccentrically braced frames strength against progressive collapse

One of the most important and effective factors of structural strength against the risk of progressive collapse is the type of lateral load bearing system of a building. In this research, strength of dual steel moment frames equipped with a variety of eccentric bracings against progressive collapse was evaluated by using nonlinear static alternate path method. 6-floored building samples were designed with steel frame using a dual steel moment system together with 3 different types of bracing, including inverted eccentrically V-shaped bracing (chevron bracing), eccentrically V-shaped bracing and eccentrically X-shaped bracing, each with two different kinds of arrangement of bracings in the structural plan, in form of alternate and neighbor. The effects of sudden removal of columns on different floors of these buildings were examined. These studies showed that dual steel moment frames equipped with eccentric bracings generally exhibited desirable strength against progressive collapse. A change in the type of bracing resulted in significant changes in the system capacity in the progressive collapse. Among the different types of braces assessed, chevron type eccentrically brace showed higher strength against progressive collapse. Also, that alternate arrangement of bracings in structure plan demonstrated better performance than neighboring arrangement.     

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。     

斜交网格结构体系在罕遇地震作用下的动力弹塑性性能研究

斜交网格体系没有传统意义上的梁和柱, 只有双向交叉的斜柱, 并由它们组成筒体。这种体系侧向刚度大, 并以斜向轴力形式传力, 有效地克服了二阶弯矩的产生, 弥补了梁柱体系抵御水平荷载的不足, 使得建筑内部布置更为自由。此类结构可视为支撑框筒体系, 不同于一般框筒结构, 其外筒由双向交叉连续环绕建筑外表面的斜杆组成, 克服了传统垂直柱受水平力过大需加斜向支撑的弱点。本文采用ABAQUS软件对这类结构直接进行罕遇地震下的动力弹塑性分析, 研究不同大小核心筒的斜交网格体系在罕遇地震作用下的力学性能。     

异形柱框-撑结构非线性时程分析

对带支撑异形柱结构进行了三维非线性时程分析。比较了几种支撑设置方案的分析结果可知,对于文中算例,只在底部设支撑,不能满足抗震规范的要求。为确保结构安全,仍需通高设支撑。所得结论可作为带支撑异形柱结构设计的参考。     

Use of steel bracing in reinforced concrete frames

In this paper the use of steel bracing in concrete-framed structures is investigated. The investigation is carried out through a series of tests conducted on a number of model frames. The object of the tests was to determine the degree of effectiveness of different diagonal bracing arrangements to increase the in-plane shear strength of the concrete frame and to observe the relative behaviour of tension and compression braces. The important question of the proper connections between the steel braces and the concrete frame is also considered. The test results indicate a considerable increase in the in-plane strength of the frame due to steel bracing. As an overall conclusion it is noted that, with proper connection between the brace and the frame, the steel bracing could be a viable alternative or supplement to shear walls in concrete framed buildings in seismic areas.