板柱-支撑结构抗震设计关键问题分析

板柱结构具有可利用空间大、布局灵活、显著降低层高等优势,但是存在结构水平刚度较弱、位移大、抗震承载力较差等问题。为解决上述问题,在板柱结构中设置屈曲约束支撑,以提高结构的抗侧刚度,增强其抗震承载力。通过对3个高度不同和2个大面积的板柱-支撑结构的计算表明,板柱结构抗侧刚度和承载力较弱的问题可通过设置适当数量的屈曲约束支撑解决。为研究板柱-支撑结构的变形、层间剪力、倾覆弯矩、支撑布置等问题,通过PKPM建模分析,结果表明:多遇地震作用下,板柱-支撑结构可采用框架结构的弹性层间位移角(1/550)来控制结构变形;板柱-支撑结构中支撑承担的楼层剪力建议不低于楼层剪力的40%;通过对比GB 50011—2010《建筑抗震设计规范》和力学概念计算得到楼层倾覆力矩的结果,认为采用规范建议的方法较为合理;支撑的竖向居中布置会减小支撑倾覆力矩占比,而对支撑剪力占比影响较小。     

高地震烈度区混凝土框架-屈曲约束支撑结构应用研究

结合某高地震烈度区工程,对混凝土框架-屈曲约束支撑结构的抗震设计方法以及相关问题进行了研究。分析了混凝土框架-屈曲约束支撑结构的最大适用高度、合理的附加刚度、适宜的层间位移角限值,并通过罕遇地震下的弹塑性时程分析考察结构的抗震性能。结果表明:混凝土框架-屈曲约束支撑结构的抗震性能优于纯混凝土结构,主体混凝土框架更容易成为"损伤可控结构",实现震后可恢复性;建议混凝土框架-屈曲约束支撑结构的最大适用高度按混凝土框架结构和框架-抗震墙结构二者最大适用高度的平均值采用;为控制主体混凝土框架的损伤,屈曲约束支撑按刚度分配的地震倾覆力矩宜大于结构总地震倾覆力矩的50%,在各层承担的楼层地震剪力不宜小于30%;建议屈曲约束支撑的附加刚度比控制在1左右,延性系数不小于3;混凝土框架-屈曲约束支撑结构相对于混凝土框架结构的层间位移角限值,在多遇地震下应根据支撑不屈服的要求做适当调整。     

板柱-人字形屈曲约束支撑抗震性能试验研究

屈曲约束支撑具有提高板柱结构侧向刚度和消耗地震能量的双重作用,且更为灵活、经济。为了提高板柱结构的抗震性能,通过在板柱之间设置人字形屈曲约束支撑,对一层一跨的1∶2比例试验模型进行了拟静力试验。试验结果表明:混凝土裂缝主要分布在距柱底1/3柱高区域和板两端1/3宽度区域,试件失效时此处破坏也最严重。结构在位移角达到1/50之后,仍具有一定的承载能力,最终在位移角为1/30(位移50 mm)的加载过程中,受拉屈曲约束支撑断裂破坏。通过ABAQUS有限元软件对其进行了数值模拟,对比分析了板柱结构和板柱-人字形屈曲约束支撑结构的骨架曲线和塑性损伤,表明人字形屈曲约束支撑能有效提高板柱结构的侧向刚度和承载力,可应用于板柱结构的抗震设计和结构加固。     

屈曲约束支撑在某礼堂抗震加固中的应用

采用屈曲约束支撑、钢支撑两种加固方案对老旧建筑物进行抗震加固改造,并分别对原结构、屈曲约束支撑加固结构、钢支撑加固结构在地震作用下的的动力特性、楼层刚度比、层间位移角等进行分析和对比。结果表明,采用屈曲约束支撑加固在小震时可有效提高结构的抗侧刚度,中震、大震时可滞回耗能,从而减轻震害,在抗震性能化设计中实现了很好的经济性;可通过选择不同性能的屈曲约束支撑达到不同的抗震性能化需求;屈曲约束支撑加固还有降低结构地震响应,提高结构抗震能力,空间布置灵活、施工简单方便、施工周期短等特点。     

屈曲约束支撑装配式钢管混凝土组合框架抗震试验性能研究

屈曲约束支撑可以有效地提高装配式钢管混凝土组合框架的抗侧移刚度和耗能减震作用。为研究地震作用下屈曲约束支撑装配式钢管混凝土组合框架的抗震性能和破坏机理,进行两层单跨屈曲约束支撑单边螺栓端板连接钢管混凝土组合框架的水平低周反复荷载试验。考察柱截面类型和端板形式对结构整体抗震性能的影响。记录和研究了此类混合结构的破坏形式和水平荷载-水平位移滞回曲线,分析和评价其骨架曲线、强度和刚度退化规律、延性和耗能等。试验研究表明,在柱截面含钢率相同条件下,抗侧移体系采用屈曲约束支撑,梁柱连接采用单边螺栓端板连接方式,屈曲约束支撑方钢管混凝土组合框架的水平承载力和初始抗侧刚度大于屈曲约束支撑圆钢管混凝土组合框架,但是其延性和耗能能力反之。试验和分析结果表明：屈曲约束支撑装配式钢管混凝土组合框架结构具有良好的抗震性能,较大的可变形能力和耗能能力,可以在多高层建筑结构中应用和推广。     

高层框筒结构框架部分剪力比研究

研究了框架-核心筒结构中框架部分对结构的抗侧贡献,指出框架部分剪力比实际上就是框架部分的层侧向刚度与该层层侧向刚度的比值,是与外荷载无关的参数。通过对一些高层和超高层框筒结构案例在地震作用下层剪力比和层倾覆力矩比的分析,指出了框筒结构抗侧性能的特点和规律。结果表明,框架部分和核心筒剪力墙共同起着抗剪和抗弯作用,当框筒结构中某些楼层框架部分剪力比很小时,核心筒剪力墙将承担绝大部分的楼层剪力,但承担的倾覆力矩增大不多,只要采取适当的加强措施就能保证结构在抗震时的安全性。     

某带设备层的超限高层建筑结构分析设计

为探究带设备层超限高层建筑的抗震性能,以位于长沙的超高层公寓式办公楼实际工程为背景,研究了设备层对结构整体参数及抗震性能的影响,重点探讨了楼层侧向刚度比的计算方法和改善楼层受剪承载力比的措施.分析结果表明,设备层的存在会引起本层框架分担剪力比的大幅度增大,但框架柱剪应力仍处于较低水平;设备层对结构周期、基底剪力及框架分担倾覆力矩比的影响可忽略不计;设备层层高突变未引起楼层塑性变形集中及结构损伤集中,罕遇地震验算结果表明结构体系合理,表明按高规算法考虑层高修正计算楼层刚度比可行;提高墙身水平筋配筋率的措施对改善楼层受剪承载力比最有效.     

底部两层框架-抗震墙砖房的抗震计算

根据底部两层框架 -抗震墙砖房的受力和变形特点 ,并基于已有研究成果 ,对这种结构的抗震计算 ,包括楼层的水平地震作用、倾覆力矩、层间剪力、框架与抗震墙内力、剪力和倾覆力矩的分配、构件受剪承载力、第二层楼板厚度及竖向荷载作用下底部两层框架内力等进行了探讨 ,提出了计算公式     

框架—核心筒结构在工程中的应用

高层建筑结构受力不同于多层建筑结构,水平风荷载或地震作用引起结构变化起主导作用。通过对框架—核心筒的平面结构布置、刚度(位移角、位移比)、周期比、强度(剪力墙和框架柱的内力计算)、框架部分地震剪力及倾覆力矩等方面进行计算比较,使其更好地发挥抗震抗风性能。     

基于不同消能器的框架结构减震性能分析与应用

减震技术在应用过程中存在的性能量化标准单一、未考虑非线性阻尼、结构损伤判别不足等问题。为推进减震技术的发展与应用,本文依照“小震、中震不坏,大震可修”的抗震设防目标,从设立性能目标、比较弹性分析方法以及计算弹塑性性能等方面,对多层框架结构分别设置屈曲约束支撑和黏滞消能器进行对比分析。研究结果表明:设置屈曲约束支撑或黏滞消能器均能满足结构在抗震设防目标下的楼层加速度、层间位移角、层间剪力等限值要求。屈曲约束支撑提供刚度,改善原结构扭转效应,适用于刚度较小的结构;黏滞消能器耗能能力强,不提供刚度,有效减小楼层加速度和楼层剪力,适用于对楼层加速度敏感或对加速度有要求较高的建筑。     

钢框架抗震改造的支撑系统研究

评估了不同支撑系统改造的抗弯钢框架的抗震性能。采用3种结构形式:中心支撑框架、防屈曲支撑框架和巨型支撑框架。设计了一横向刚度不足的9层钢框架,满足规范对高地震灾害区域结构的侧移要求。用中心支撑、防屈曲支撑和巨型支撑改造框架,进行非弹性时程分析,评估地震作用下的结构性能。以局部变形(杆件转角)和整体变形(层间及屋顶侧移)为参数,比较改造框架非弹性性能的不同。结果表明:巨型支撑框架是最有效率的支撑系统,其最大层间侧移比抗弯框架低70%,比中心支撑框架低50%。侧移的减小量与地震特性有关,尤其是频率。防屈曲支撑的抗震性能仅稍优于巨型支撑框架,但其总质量更大。巨型支撑框架的杆件和节点用钢量比中心支撑框架低20%,既降低了费用又体现了抗震优势。     

钢框架抗震改造的支撑系统研究

评估了采用不同支撑系统改造的抗弯钢框架的抗震性能。共采用3种结构形式:中心支撑框架、防屈曲支撑框架、巨型支撑框架。设计了一横向刚度不足的9层钢框架,满足规范对高地震灾害区域结构的侧移要求。用中心支撑、防屈曲支撑和巨型支撑改造框架。进行非弹性时程分析,评估地震作用下的结构性能。以局部变形(杆件转角)和整体变形(层间及屋顶侧移)为参数,比较改造框架非弹性性能的不同。结果表明:巨型支撑框架是最有效率的支撑系统,其最大层间侧移比抗弯框架低70%,比中心支撑框架低50%。侧移的减小量与地震特性有关,尤其是频率。防屈曲支撑的抗震性能仅稍优于巨型支撑框架,但其总质量更大。巨型支撑框架的杆件和节点用钢量比同心支撑框架低20%,既可降低费用又具有抗震优势。     

Bracing systems for seismic retrofitting of steel frames

The present study assesses the seismic performance of steel moment resisting frames (MRFs) retrofitted with different bracing systems. Three structural configurations were utilized: special concentrically braces (SCBFs), buckling-restrained braces (BRBFs) and mega-braces (MBFs). A 9-storey steel perimeter MRF was designed with lateral stiffness insufficient to satisfy code drift limitations in zones with high seismic hazard. The frame was then retrofitted with SCBFs, BRBFs and MBFs. Inelastic time-history analyses were carried out to assess the structural performance under earthquake ground motions. Local (member rotations) and global (interstorey and roof drifts) deformations were employed to compare the inelastic response of the retrofitted frames. It is shown that MBFs are the most cost-effective bracing systems. Maximum storey drifts of MBFs are 70% lower than MRFs and about 50% lower than SCBFs. The lateral drift reductions are, however, function of the characteristics of earthquake ground motions, especially frequency content. Configurations with buckling-restrained mega-braces possess seismic performance marginally superior to MBFs despite their greater weight. The amount of steel for structural elements and their connections in configurations with mega-braces is 20% lower than in SCBFs. This reduces the cost of construction and renders MBFs attractive for seismic retrofitting applications.     

用附加防屈曲支撑钢筋混凝土框架加固既有钢筋混凝土框架抗震性能试验研究

利用附加防屈曲支撑（BRB）钢筋混凝土框架对既有钢筋混凝土框架结构进行减震加固。设计3榀钢筋混凝土框架,其中2榀为附加设置BRB加固框架的钢筋混凝土框架,另外1榀为纯钢筋混凝土框架以作对比。通过低周反复加载试验,验证所设计的外贴防屈曲支撑钢筋混凝土框架加固既有钢筋混凝土框架的可行性。分析既有及外贴钢筋混凝土框架的开裂、荷载 侧移滞回曲线、骨架曲线、荷载 防屈曲支撑变形曲线,以及等效黏滞阻尼比和等效刚度等特性。结果表明：所设计的附加钢筋混凝土框架、预埋件、连接构造受力可靠,附加设置BRB的钢筋混凝土加固框架具有良好的减震耗能能力;水平荷载-侧移滞回曲线圆润饱满;防屈曲支撑在小层间位移角下可屈服耗能,大位移下不失效,耗能稳定;附加框架能够显著增加既有钢筋混凝土框架结构的阻尼,有效降低地震反应,改善既有框架结构抗震性能。     

Seismic design and assessment for midrise buildings equipped with damped-outrigger system

The damped-outrigger system has been proposed to improve the performance of conventional outrigger systems in controlling the structural seismic response by increasing the damping and stiffness. The purpose of this study is to demonstrate the effectiveness of using damped-outrigger systems in midrise buildings and provide engineers with a comparison between conventional structural systems such as moment resisting frame (MRF) and buckling-restrained braced frame (BRBF) in proposing the most suitable structural system. In this study, the buckling-restrained brace and viscous damper are adopted as the energy dissipation devices in the damped-outrigger system. A total of 48 midrise numerical models with various building heights and structural systems are analyzed using nonlinear response history analysis and incremental dynamic analyses. The analysis results show that the midrise buildings equipped with a damped-outrigger system with either viscous damper or buckling-restrained brace (BRB) can reach similar and even better seismic performance when compared with the BRBF; it also reduces the structural responses by around 30% for the maximum roof drift and acceleration responses when compared with MRF. The analysis results could provide a reference for structural engineers when selecting suitable lateral force resisting systems for midrise buildings.     

高重剪比下配置栓钉的板柱节点抗震性能试验研究

为研究高重剪比下配置栓钉的钢筋混凝土板柱节点的抗震性能,完成了3个重剪比分别为0.886、0.844和0.802的板柱节点试件在往复水平力作用下的拟静力试验。试件Joint 1和Joint 2的栓钉采用正交布置,Joint3的栓钉采用放射状布置。试验结果表明：3个试件的楼板均发生了冲切破坏,试件Joint1冲切破坏发生在栓钉群内,试件Joint2冲切破坏发生在栓钉群外,试件Joint3在栓钉群内、外均发生冲切破坏;破坏时3个试件的层间位移角分别为1/69、1/46和1/40;配置抗冲切栓钉的板柱节点在高重剪比下仍具有良好的水平变形能力,采用非预应力混凝土楼板栓钉群外冲切承载力计算公式的计算结果与试验结果符合良好。     

Design and behaviour of a reinforced concrete high‐rise tube building with belt walls

This paper discusses modelling, analysis and design issues for a 55‐storey hotel building recently planned for New York City, USA. The lateral force resistance of the investigated building primarily makes use of exterior reinforced concrete shear walls in one direction and exterior reinforced concrete moment frames in the other direction, in which tube action credited to the connection of the walls and frames was designed to play a significant role in the lateral stiffness and strength. In addition, a full‐storey belt wall system, enclosing the entire perimeter of the building at approximately the mid‐height, is expected to provide a considerable contribution to the lateral force resistance. In this paper, the contribution of tube action and the belt wall system to structural behaviour is investigated in terms of quantitative measures such as lateral drift, building dynamic properties and flange frame contribution to overturning moment resistance. In addition, axial force distribution among the various vertical members under lateral forces is discussed for each of the two principal building directions. Finally, the seismic behaviour of the investigated building is qualitatively discussed in order to propose a seismic force‐resisting system classification into which this concrete tube system would fit. Copyright © 2010 John Wiley & Sons, Ltd.     

A modified dynamic inelastic analysis of tall buildings considering changes of dynamic characteristics

Pushover analysis is commonly used to evaluate the inelastic ultimate capacity of structures. However, pushover analysis is carried out based on constant distributions throughout the incremental analysis, which cannot capture the variation in the acceleration profile due to inelastic behavior. For this reason, when plastic hinges form in structure, constant distributions of lateral forces cannot be used any longer. Conventional dynamic inelastic method by time‐history analysis can be used for specific earthquakes to consider the changes in the distribution of lateral forces. This alternative approach, however, is not practical due to the volume of calculations required. In this study, MOdified Dynamic Inelastic Analysis (MODIA) is introduced to capture a distribution proportional to changing mode shapes affected by the change of stiffness. In this method, as a structure enters into the inelastic range, the distribution of lateral forces is changed according to the mode shapes of structure. The efficiency of the proposed method is verified by comparing the results from DRAIN. A 7‐story moment resisting frame and a 36‐story existing structure were analysed by both methods. The comparison showed a good agreement. The story shear–drift relationship, base shear, drift, ductility and overturning moment for the structures are also evaluated. Copyright © 1999 John Wiley & Sons, Ltd.     

防屈曲支撑-钢筋混凝土框架结构基于能量平衡的抗震塑性设计

为确定防屈曲支撑在结构中的布置方式以使结构抗震性能充分发挥,提出了基于能量平衡的防屈曲支撑 钢筋混凝土框架结构抗震塑性设计方法。构建了结构的“强柱弱梁”整体屈服机制,采用侧力比将总结构体系离散为防屈曲支撑体系和纯框架体系,并建立了结构的双线性能力曲线。基于能量平衡方法计算结构的设计基底剪力并分别得到支撑体系和框架体系的设计侧向力,进而完成支撑的截面设计。按照塑性内力分配机制和考虑支撑屈服后性能,计算梁柱构件内力需求。以一幢5层结构为例,分别设计了不同侧力比的14个结构模型,对比了基底剪力、防屈曲支撑面积和梁柱钢筋用量等。通过22条地震波下的弹塑性时程分析,研究了不同侧力比结构的最大层间位移角、屈服机制、楼层剪力比、支撑最大位移延性、累积位移延性和结构残余层间位移角。分析结果表明：所提出的方法能实现结构的预期失效模式,并满足结构的抗震性能要求,并建议设计侧力比选取在0.3~0.5之间。     

The seismic behaviour of steel moment-resisting frames with stiffening braces

The present paper deals with the seismic behaviour of steel structures which are designed in the attempt of exploiting the dual characteristics of moment resisting frames (MRFs) and concentrically braced frames (CBFs) as lateral force resisting systems. Three prototype frames are studied within the context of Eurocode 8 (EC8) provisions; these are MRFs which are traditionally designed, against ultimate seismic actions (ULS), without checking serviceability limit state rules (SLS-interstory drift limits). To fulfill these requirements concentrical braces are inserted in the frames, which are not considered in the collapse resistance of the structural system. The non-linear behaviour of these systems under ultimate seismic environment is studied and compared to the one of the unbraced MRFs. The influence of second order effects is also investigated.