不同类型结构中楼梯受力性能研究

通过对有楼梯的框架结构、框架-剪力墙结构和剪力墙结构的地震反应分析,研究了不同类型结构中楼梯构件的受力性能。结果表明,在框架结构中当楼梯与主体结构共同工作时,楼梯中梯段板、梯梁和梯柱等构件的内力显著增大,且受力状态复杂,从而造成楼梯构件不同程度的破坏;在框架-剪力墙结构和剪力墙结构中,当楼梯与主体结构共同工作时,楼梯中梯段板的内力明显增大,且受力状态复杂,易造成梯段板的破坏;而梯梁、梯柱等所受内力较小,不易产生破坏。     

8度抗震设防烈度区板柱-剪力墙高层结构安全性能分析

板柱结构节约结构空间是一种常用建筑结构形式，通常也被认为是抗震薄弱体系，我国GB 50011—2010《建筑抗震设计规范》对板柱结构使用范围以及适用高度作了严格限定，与国外规范相比较，我国结构规范对板柱结构有细致严格的构造要求。结合北京8度区某17层带边框高层板柱-剪力墙结构的实际工程，通过ETABS有限元程序对结构进行多遇地震作用分析，重点研究了楼板应力分布。采用SAUSG有限元程序补充罕遇地震下有限元非线性分析，研究了墙柱损伤情况与主要构件性能。应用SAP2000程序采用拆除构件法，分析了板柱结构抗连续倒塌能力。研究结果表明，在满足规范规定构造措施前提下，带边框板柱-剪力墙结构具有较好的承载能力、良好的抗震性能和抗连续倒塌能力，可以达到8度抗震设防烈度区高层建筑安全性能要求。     

钢框架-带缝钢板剪力墙结构受力性能分析

本文对4种钢框架、6种带缝(两排)钢板剪力墙片(四周与构件无连接)和6种固接的钢框架-带缝钢板剪力墙结构在3种不同竖向荷载作用下的抗侧能力和往复荷载下的滞回性能进行了研究,并对比分析。结果表明:前两种结构的侧移刚度、抗侧能力相对较低,屈曲后刚度退化快;钢框架-带缝钢板剪力墙结构的侧移刚度、抗侧能力和耗能能力比前两种结构有明显的提高,说明钢框架与带缝钢板剪力墙片固接后工作协调性能良好。带缝钢板剪力墙片与钢框架-带缝钢板剪力墙结构的整体设计参数宽高比W/H,开缝设计参数开缝墙肢的高宽比h/b、宽厚比b/t、开缝墙肢与剪力墙的高宽比h/H对结构的抗侧能力和滞回性能有很大影响。W/H增大,结构的抗侧能力增强,滞回性能降低;h/b、b/t、h/H增大,结构的抗侧能力降低,滞回性能提高。     

方钢管混凝土框架-十字加劲薄钢板剪力墙的力学性能研究

采用大型通用非线性有限元软件ABAQUS 6.10分别对方钢管混凝土框架-十字加劲薄钢板剪力墙和非加劲薄钢板剪力墙进行了数值分析,对二者的受力特征、刚度、极限承载力、剪力分配及柱子的受力特征进行了研究.结果表明:当肋板刚度比为30时,十字加劲肋能够提高钢板剪力墙结构的弹性屈曲荷载、极限承载力、初始刚度,降低柱子轴压比对剪力初始分配的影响;在加载的初始阶段(顶点侧移角小于0.2％),钢板剪力墙承担了大部分剪力,随后墙板承担剪力的比例逐渐下降,框架承担的比例逐渐上升,当顶点侧移角达到1％时,框架和钢板剪力墙承担剪力的比例保持不变;方钢管混凝土框架-薄钢板剪力墙的滞回环饱满,滞回性能稳定.由于薄钢板墙拉力场作用,方钢管混凝土柱壁易与混凝土发生分离,在设计时应予以注意.     

钢板剪力墙结构边框柱的稳定性研究

钢板剪力墙结构是一种新型经济高效的抗侧力体系,由钢框架内嵌钢板组合形成。钢板剪力墙结构的边框柱在附加弯矩作用下常产生"沙漏"这种不良的破坏模式,为此加拿大CAN/CSA(S16-01)规范依据薄腹梁理论柔度系数ωt给出了钢板墙结构边框柱的最小惯性矩要求。薄腹梁理论适用于极薄板,而我国规范和实际应用中多选用厚板墙或加劲墙,板厚往往处于中厚板范畴,柔度系数ωt的适用性有待讨论。本文结合经典的边框柱柔度限值推导过程,利用承载力和应力均匀性两种评价方法,对CAN/CSA S16-01规范给出的柱柔度限值小于或等于2.5的适用性进行了验证。基于通用高厚比的概念给出了钢板剪力墙结构的弹性抗剪承载力,同时采用拉力场机制份额考虑了内嵌钢板厚度的影响,修正了柱柔度系数。研究结果表明钢板墙宽高比较大时,CAN/CSA S16-01规范限值不满足要求,柱柔度限值应缩小到2.1,对应边框柱的惯性矩要求应扩大为S16-01规范限值的2倍。     

梁柱-板柱组合结构(住宅)体系模型振动台试验研究

梁柱-板柱组合结构(住宅)体系由上部大开间板柱结构和底部框架结构构成，是一种可持续发展的新型结构形式。通过两个12层l：15模型的振动台对比试验，探讨其动力特性、地震反应和破坏情况。试验表明，该体系的抗震性能介于框架结构和板柱结构之间。总层数在12层以下时，不设剪力墙的该体系在7度区基本上满足规范要求，合理设置剪力墙后可用于8度区。     

新型竖向连接的带暗支撑预制叠合剪力墙抗震试验研究

为研究得到带暗支撑的预制叠合板剪力墙合理的竖向连接方法,分别设计了1片带钢板暗支撑的局部高阻尼混凝土U型连接预制叠合剪力墙和1片带90°钢板暗支撑的局部高阻尼混凝土预制叠合剪力墙,并设计1片普通钢板暗支撑现浇剪力墙做对比,进行了拟静力试验研究,对比三个试件在受力作用下的承载能力、滞回曲线、骨架曲线、位移延性、刚度退化、耗能性能、裂缝发展情况以及破坏形态。研究结果表明:采用U型连接的带暗支撑预制叠合板剪力墙与现浇带暗支撑剪力墙的承载能力以及抗震性能基本相近,90°暗支撑的预制叠合板剪力墙在减少钢材用量的前提下也拥有足够的承载能力和良好的抗震性能。     

框剪结构抗震剪力墙数量的优化准则证明

将框剪结构连续化，按振型组合法证明了同时满足规范允许顶点侧移和层间侧移角的最少抗震剪力墙数量为最优剪力墙量，相应的设计为最优设计。     

FRC框架结构的损伤程度控制及性能评估

为研究纤维增强混凝土（FRC）框架结构体系预期损伤部位的损伤程度控制和性能评估方法,采用ABAQUS有限元软件对该框架结构模型进行动力时程分析。针对该结构体系,研究其各种性能水准极限状态的定性描述和量化方法,并进行结构抗震性能评估。研究结果显示,预期损伤部位采用FRC材料,可以减小RC框架结构的层间残余侧移角、柱端截面最大转角和柱截面最大残余转角,可以控制整体结构和构件的损伤程度。给出FRC框架结构在不同性能水准下分别以柱截面转角、层间侧移角和层间残余侧移角为性能指标的限值。综合考虑FRC材料的特性和仿真结果的分析,建议选用层间残余侧移角进行性能评估更为合理。考虑8倍板厚翼缘宽度,柱梁抗弯承载力比达到1.2,FRC框架结构在8度设防烈度对应的地震作用下可达到性能等级D。     

水平荷载作用下密肋复合墙结构的变形计算

密肋复合墙结构是近年来应用在住宅领域中的一种新型建筑结构体系,目前关于地震作用下密肋复合墙结构的变形计算方法尚不完善,采用等效剪力墙结构模型不能同时考虑密肋墙的有效弹性模量和有效面内剪切模量,导致等效模型在水平荷载作用下的变形与实际结构存在一定误差.在试验研究基础上,依据铁木辛柯剪切梁理论并考虑密肋墙体弹性常数取值和构造特点,建立了包含剪切变形在内的密肋复合墙侧移曲线方程;同匀质混凝土墙侧移方程相比,密肋墙侧移方程中的弹性常数是与墙体构造有关的变参数表达式.算例分析表明,等效混凝土墙结构模型的侧移变形计算结果较实际结构偏小,在中高层结构中表现尤为明显,可能引起不可忽略的误差而导致结构存在安全隐患;建议对等效混凝土墙模型的侧移变形结果进行修正,给出了初步的修正系数供工程设计参考.     

Implications of the spandrel type on the lateral behavior of unreinforced masonry walls

Seismic response of unreinforced masonry (URM) buildings is largely influenced by nonlinear behavior of spandrels, which provide coupling between piers under in‐plane lateral actions. Seismic codes do not appropriately address modeling and strength verification of spandrels, adapting procedures originally proposed for piers. Therefore, research on spandrels has received significant attention in some earthquake‐prone countries, such as Italy and New Zealand. In the last years, the authors of this paper have performed both monotonic and cyclic in‐plane lateral loading tests on full‐scale masonry walls with single opening and different spandrel types. Those tests were carried out in a static fashion and with displacement control. In this paper, experimental outcomes for two as‐built specimens are presented and compared with those obtained in the past for another as‐built specimen with a wooden lintel above the opening. In both newly tested specimens, the masonry above the opening was supported by a shallow masonry arch. In one of those specimens, a reinforced concrete (RC) bond beam was realized on top of the spandrel, resulting in a composite URM‐RC spandrel. Then, the influence of spandrel type is analyzed in terms of observed damage, force–drift curves, and their bilinear idealizations, which allowed to compare displacement ductility and overstrength of wall specimens. Furthermore, effects of rocking behavior of piers are identified, highlighting their relationship with hysteretic damping and residual drifts. Copyright © 2014 John Wiley & Sons, Ltd.     

Three‐dimensional beam–truss model for reinforced concrete walls and slabs – part 2: modeling approach and validation for slabs and coupled walls

A three‐dimensional beam–truss model (BTM) for reinforced concrete (RC) walls that explicitly models flexure–shear interaction and accurately captures diagonal shear failures was presented in the first part of this two‐paper series. This paper extends the BTM to simulate RC slabs and coupled RC walls through slabs and beams. The inclination angle of the diagonal elements for coupled RC walls is determined, accounting for the geometry of the walls and the level of coupling. Two case studies validate the model: (1) a two‐bay slab–column specimen experimentally tested using cyclic static loading and (2) a five‐story coupled T‐wall–beam–slab specimen subjected to biaxial shake table excitation. The numerically computed lateral force–lateral displacement and strain contours are compared with the experimentally measured response and observed damage. The five‐story specimen is characterized by diagonal shear failure at the bottom story of the walls, which is captured by the BTM. The BTM of the five‐story specimen is used to study the effects of coupling on shear demand for lightly reinforced RC coupled walls. The effect of mesh refinement and bar fracture of non‐ductile transverse reinforcement is studied. Copyright © 2016 John Wiley & Sons, Ltd.     

Frequency analysis of coupled shear wall assemblies

The finite strip procedure is used to predict the free vibration response of both planar and non-planar coupled shear wall assemblies. The solid walls are considered as vertical cantilever strips and a comparison is made between modelling the spandrel beams as discrete beams and as an equivalent continuum with orthotropic plate properties. It is shown that both approaches lead to essentially the same frequencies. The effects of vertical inertial forces and shear deflection are included, and structures considered may have properties that vary with height. The method presented appears to be more versatile than previously published techniques and numerical comparisons with existing methods indicate the predicted results to be accurate.     

Biaxial effects in modelling earthquake response of R/C structures

Recent studies reveal that R/C structural members subjected to biaxial flexure due to two-dimensional earthquake excitation can deform much more than would be predicted by conventional one-dimensional response analysis. The biaxial flexure may therefore have a significant effect on the dynamic collapse process of structures subjected to intense ground motions. The present paper is intended to develop a new formulation of the two-dimensional restoring force model of R/C columns acted upon by biaxial bending moments, and to discuss the dynamic response properties of R/C structures. The model considered is a two-dimensional extension of various non-linear models for one-dimensional response analysis, including the degrading trilinear stiffness model which is one of the simpler idealizations of the restoring force characteristics of flexural-failure-type R/C structures. The modelling validity is then examined by comparison with experimental data on the biaxial bending behaviour of R/C columns. Calculations are made to study the role of different system properties on the influence of inelastic biaxial bending on the dynamic structural response. It is shown that the inelastic biaxial effect is generally significant and, in some cases, critical in the case of R/C structures with stiffness-degrading properties, while the effect is not so important for the non-degrading inelastic cases.     

Mitigation measures for pile groups behind quay walls subjected to lateral flow of liquefied soil: Shake table model tests

This paper presents experimental results of a series of 1g shake table tests on mitigation measures for a model consisting of a 3×3 pile group and a sheet-pile quay wall in which the pile group was subjected to liquefaction-induced lateral spreading. First, general observations associated with the mechanism of lateral spreading and pile response are presented based on tests without remedial measures, followed by in depth discussions. Second, three remedial techniques were deployed to provide an adequate seismic performance of the pile group and the quay wall: (i) mitigating sheet pile of floating type, (ii) mitigating sheet pile of fixed end type, and (iii) anchoring the quay wall to a new pile row. The main objective of these mitigation methods was to restrict ground distortion behind the quay wall, enhancing seismic response of pile group and quay wall. This mitigation philosophy was decided based on the outcome of the first part, which consisted of a series of tests without mitigation measures. In addition, it should be noted that the proposed countermeasures were selected to be applicable for existing vulnerable pile groups, which are at risk of liquefaction and lateral spreading. Results of different mitigation tests are comparatively examined using a parameter called reduction factor, and the effectiveness of each countermeasure is discussed in detail. The results demonstrate that by applying the proposed mitigation measures the seismic performance of both pile group and quay wall can be improved, as a result of reduction in soil displacement and velocity of soil flow.     

Inelastic analysis of R/C coupled shear walls

This paper presents a method of analysis capable of calculating the response of an R/C coupled shear wall structure subjected to strong earthquake motion without major complications existing in the method itself. The relative simplicity is achieved while retaining reasonable reliability in the computed response. The reliability of the computed results are tested against 1- the measured responses of a cantilever column member and a 6-storey coupled shear wall system under static cyclic lateral loads; and 2- the measured responses of two coupled shear wall structures which were subjected to simulated earthquake motions on the University of Illinois Earthquake Simulator. The effects of moment-axial force interaction in the wall members on the computed overall responses of the coupled shear wall structures and on the behaviour of each individual wall are discussed.     

楼板及其配筋在RC框架结构实现抗震延性机制中的作用分析

总结采用梁有效翼缘来考虑楼板及配筋对“强柱弱梁”机制形成的影响的实验和数值仿真研究。基于SAP2000采用三种侧向加载模式对RC框架结构不带楼板、不带楼板考虑梁刚度放大、带楼板的三个模型进行pushover分析,对力与位移的关系曲线、塑性铰的出铰顺序以及顶点位移与层间位移等方面进行探讨。结果表明:三个模型的“强柱弱梁”现象不带楼板的纯框架结构最明显,考虑梁刚度放大的模型次之,带楼板结构最不明显,证明负弯矩承载力和刚度等反映“强柱弱梁”的参数及塑性铰的出现顺序与楼板、板内配筋存在明显的对应关系;楼板及配筋影响框架结构的整体变形性能和塑性耗能能力,是抗震延性机制实现的重要影响因素。在后续的结构设计中,建议考虑实际楼板和钢筋建模进行计算分析。     

剪力墙结构层间位移计算方法探讨

规范对高层剪力墙结构层间位移进行限制时,没有考虑结构体系侧移模式不同的影响,这对以弯曲变形为主的结构会造成很大的误差,甚至得出一些与实际情况完全不相符的结论。针对这一问题,本文根据剪力墙结构的受力特点,将楼层位移分为有害位移和无害位移,将层间位移分为名义层间位移Δui和有害层间位移Δui~,用倒三角形分布水平荷载的等截面悬臂杆件的弯曲变形曲线作为剪力墙结构的近似侧移曲线,从理论上分析了剪力墙结构的名义层间位移、有害层间位移、层间相对转角以及截面的弯曲曲率之间的关系,给出有害层间位移的实用计算公式。最后,对比分析了控制剪力墙层间变形的几种不同方法,并通过算例分析验证了本文方法实用可行,与实际情况符合较好。     

Seismic response of simple structures using spring-assisted sliding slabs with coulomb damping

Coulomb damping can be utilized effectively to reduce the dynamic response of structures subjected to seismic ground motions. To activate this damping, some parts of a vibrating structure are allowed to slide at rough interfaces. The dynamic response of structures provided with sliding interfaces at the base, between a floor slab and frame and in the cross bracings of a frame has been examined recently. In this paper, a simple slab sliding system provided with a spring to introduce a recovery mechanism and to reduce the sliding displacement requirement for low frequency structures has been examined. The equations of motion for this system are developed. An approach is presented to solve these coupled equations for earthquake induced ground motions. Structures with varying frequency and friction characterisics are considered and the numerical results are presented in response spectrum form. It is observed that, in low frequency structures, provision of a rather weak spring can reduce the sliding displacement requirements without significantly increasing the forces in the supporting frame and the acceleration input to supported secondary systems.     

钢管混凝土框架-核心筒混合结构连续倒塌非线性动力分析

为研究钢管混凝土框架-核心筒混合结构在局部构件失效后的连续倒塌机制,基于ABAQUS纤维梁单元和分层壳单元,采用课题组开发的材料本构子程序iFiberLUT,进行了一栋33层钢管混凝土框架-核心筒混合结构在1、17、33层柱和核心筒墙体失效工况下的连续倒塌非线性动力分析,研究了典型柱和剪力墙失效后剩余结构的抗连续倒塌机制。结果表明:33层构件失效时上部节点位移反应最大,17层次之,1层最小,相比核心筒墙体失效,柱失效时上部节点竖向位移更大,震荡更明显;各工况作用对核心筒影响均较小,且核心筒的存在增强了楼板的薄膜效应,提高了结构抗倒塌能力,失效位置距核心筒越近提高越显著;典型构件失效后结构的传力路径遵循"就近原则"向周围构件传递,楼板和核心筒有力的提高了结构的冗余传递路径和整体性。