Seismic response of multistory reinforced concrete frame with vertical mass and stiffness irregularities

Irregular buildings behave differently as compared with regular buildings. Seismic design codes have quantified the irregularities in terms of magnitude only ignoring the effect of irregularity location. In the present study, a single parameter to quantify mass, stiffness and strength irregularity in terms of both magnitude and location is proposed on the basis of the dynamic characteristics of the building. Furthermore, building models with different types of irregularity with variation in magnitude and location of irregularity are analyzed by subjecting them to an ensemble of 27 ground motions to create a seismic response databank. In the analysis, the torsional effects generated due to irregularities in the building systems (as per EC 8:2004 provisions) are included. On the basis of regression analysis conducted on this seismic response databank, equations to estimate seismic response parameters such as fundamental period, maximum roof displacement and maximum inter‐story drift ratio etc. are proposed for the irregular buildings in terms of the proposed irregularity index. Finally, applicability of the proposed equations is discussed in brief, and these equations are validated for 2D and 3D building models. Copyright © 2012 John Wiley & Sons, Ltd.     

Seismic behavior of tall buildings using steel–concrete composite columns and shear walls

For the seismic design of tall building structures, the behavior under severe earthquakes should be carefully considered and the upper limit of inter‐story deformations are often defined by the design codes. To improve the performance of structures under severe earthquakes, composite structural members, including steel reinforced column and steel plate reinforced shear wall, are often adopted. In the present work, the seismic behavior of tall buildings using steel–concrete composite columns and shear walls is investigated numerically. Fiber beam–column element models and multilayer shell models are adopted to establish the finite element model of structure, and the material nonlinearities are described by the plasticity and damage models. The accuracy of the developed models is verified by the experimental results of a single shear wall. Systematic numerical simulations are performed for the tall building structures subjected to different earthquakes. The comparative study indicates that the nonlinear redistribution of internal forces plays a very important role for the performance of tall buildings under severe earthquakes.     

A model for earthquake risk management based on the life-cycle performance of structures

Over 50 years of design life, buildings are exposed to different magnitudes and frequencies of earthquakes that require consideration of life-cycle cost (LCC). The LCC entails quantifying the building performance under seismic hazard and investments throughout the life of the structures. Traditional LCC utilises probabilities of being in different damage states. However, for buildings with inherent irregularities (e.g. vertical irregularity and plan irregularity), these probabilities are not readily available. In this paper, a system-based approach, utilising fuzzy set theory, is used to quantify the possibility of being in different damage states. The analysis is limited to study the effect of seismic exposure on the building LCC. The proposed method is illustrated with two case studies, a six-storey reinforced concrete (RC) building located in Vancouver, Canada, and vulnerability of an urban centre with 1000 RC buildings. Furthermore, sensitivity analysis is carried out to highlight the impact of different building performance modifiers on the LCC.     

Optimum seismic design of steel framed‐tube and tube‐in‐tube tall buildings

The relatively large number of structural elements and the variety of design code requirements complicate the design process of tall buildings. This process is exacerbated when the target is to obtain the seismic code‐compliant optimal design with minimum weight. The present paper aims at providing a practical methodology for the optimal design of steel tall building structures considering the constraints imposed by typical building codes. The applicability of the proposed approach is demonstrated through the determination of the optimal seismic design for 20‐, 40‐, and 60‐story buildings with a framed tube as well as a tube‐in‐tube system. Such a design gives rise to a basis for the fair comparison of the behavior of the framed tube with that of the tube‐in‐tube system under applied loads. The optimal weight of the buildings with the tube‐in‐tube system turns out to be slightly less than that of the buildings with the conventional framed‐tube system.     

Performance‐based seismic design of an irregular tall building in Istanbul

Structural design of a 50‐story tall reinforced concrete residential building, which was planned to be constructed in Istanbul and given up afterwards by the investor, has been completed in accordance with the draft version of Seismic Design Code for Tall Buildings in Istanbul that adopts performance‐based seismic design as the basic approach as Tall Buildings Initiative Guidelines do. Seismic design of the building has formed the main part of the structural design process due to high seismicity of the proposed location and extremely irregular floor plan not conforming to usual tall building structures. The building consists of two individual buildings linked through sky floors at the top 12 stories whose design was one of the most challenging works. The building has been designed for design basis earthquake by elastic response spectrum analysis, and its seismic performance has been checked for maximum considered earthquake by nonlinear time‐history analyses carried out using PERFORM‐3D. Copyright © 2015 John Wiley & Sons, Ltd.     

Design and seismic response of tall chevron panel buckling‐restrained braced steel frames

The numerical analysis of the seismic performance for tall chevron panel buckling‐restrained braced steel frames (PBRBFs) under small and strong earthquake excitations has been carried out to investigate a capacity design procedure for chevron PBRBFs and to examine the effects of axial strength distribution of braces along the height of buildings, vertical supports of braces for the braced beams and the overstrength of braces on the seismic response of PBRBFs. It revealed that the chevron braces that remained elastic can actually provide the vertical supports for the braced beams. Under severe earthquake excitations, the vertical supports deteriorated greatly after braces yielding. The PBRBFs designed by omitting vertical supports of braces for the braced beams and considering the overstrength of braces exhibited superior performance with smaller plastic deformations for braced beams and reduction in ductility demands for panel buckling‐restrained braces (PBRBs) as compared with the others. The distribution of yielding for PBRBs in 10‐story buildings verified that the participation from the higher modes is not very remarkable and that the capacity design based on the first‐mode response can be considered for multistory PBRBFs. Moreover, on the basis of the analysis results of the 30‐story PBRBF, the participation of the higher modes should be taken into account for high‐rise PBRBFs. Copyright © 2011 John Wiley & Sons, Ltd.     

关于超限高层建筑抗震设防审查的若干讨论

超限高层建筑的抗震设防审查,是提高高层建筑工程抗震设计的可靠性、避免抗震安全隐患,同时又促进高层建筑技术发展的有力手段,本文就抗震设防审查的必要性、主要内容和实现超限高层建筑设计的重要概念及关键技术措施提出若干参考意见。     

Optimum strength distribution for seismic design of tall buildings

This paper examines the effects of strength distribution pattern on seismic response of tall buildings. It is shown that in general for an MDOF structure there exists a specific pattern for height‐wise distribution of strength and stiffness that results in a better seismic performance in comparison with all other feasible patterns. This paper presents a new optimization technique for optimum seismic design of structures. In this approach, the structural properties are modified so that inefficient material is gradually shifted from strong to weak areas of a structure. This process is continued until a state of uniform deformation is achieved. It is shown that the seismic performance of such a structure is optimal, and behaves generally better than those designed by conventional methods. The optimization algorithm is then conducted on shear building models with various dynamic characteristics subjected to a group of severe earthquakes. Based on the results, a new load pattern is proposed for seismic design of tall buildings that is a function of fundamental period of the structure and the target ductility demand. The optimization method presented in this paper could be useful in the conceptual design phase and in improving basic understanding of seismic behavior of tall buildings. Copyright © 2007 John Wiley & Sons, Ltd.     

广州爱群会景湾超限高层结构设计

广州爱群会景湾由A,B两幢塔楼和裙房组成,两个塔楼高度184.6m。存在平面不规则、竖向不规则、大底盘多塔楼和高位转换等超限情况,属于复杂高层建筑结构。结构设计时从抗震概念设计出发,适当提高结构抗震性能目标,采用不同的计算软件进行结构分析,采取有针对性的构造加强措施,从而确保了结构的抗震安全性。     

超限高层建筑结构基于性能抗震设计的研究

基于性能的设计方法已引起工程界的关注 ,在超限高层建筑的结构抗震设计中 ,采用基于性能要求的抗震设计方法 ,有助于提高高层建筑工程抗震设计的可靠性、避免抗震安全隐患 ,同时又促进高层建筑技术发展。本义阐述基于性能抗震设计方法与常规抗震设计方法的比较 ;针对超限高层建筑结构的特点 ,提出结构的抗震性能目标、性能水准以及实施性能设计的主要方法 ,包括性能水准判别准则、性能目标的选用及结构计算和试验要求。文中还列举了应用性能设计理念和要求的部分工程实例。     

Evaluation of seismic behaviour of steel special moment frame buildings with vertical irregularities

This paper concentrates on investigating the seismic behaviours of vertically irregular steel special moment frame (SMF) buildings by comparison with the regular counterpart. All buildings in this study were assumed to be located in Los Angeles, and subjected to 20 earthquake ground motions with a seismic hazard level of 2% probability of exceedance in 50 years. The beam–column connections of the buildings were modelled to consider the panel zone deformation. In addition, a ductile connection model accompanied by strength degradation was incorporated to the analysis programme in an effort to obtain more accurate response results. Three types of irregularities (mass, stiffness and strength irregularity) specified as vertical irregularities in the IBC 2000 provisions were imposed to the original building. Nonlinear static and dynamic analyses were performed, and the confidence levels of which the performance objective will be satisfied were calculated as well. The effects of different irregularity types and levels on the seismic behaviours of the buildings were investigated and discussed in terms of the height‐wise distribution of storey drifts, maximum storey drift demands, global collapse storey drift capacities and confidence levels. Copyright © 2010 John Wiley & Sons, Ltd.     

试谈高层建筑结构抗震设计理念及方法

从改变物体运动状态的根本原因出发我们出得有关高层建筑结构抗震设计理念的设计根本,就是去削弱或抵消掉影响高层建筑的外力。针对现阶段我们国家的有关高层建筑结构抗震设计理念及方法的研究成果笔者从个人专业观点稍作分析。     

深圳证交所大厦弹塑性动力分析

深圳证交所大厦的结构总高度为236.95m,为超B级高度的超限高层建筑,存在侧向刚度不规则、竖向体型不规则和抗侧力构件不连续等3项结构不规则。为评估结构在罕遇地震作用下的性能,基于ABAQUS程序和混凝土塑性损伤模型,利用自行开发的前处理转换程序和材料用户子程序,对结构进行弹塑性动力时程分析,给出了在罕遇地震场地波和ElCentro波作用下结构变形、关键构件的塑性损伤以及结构整体弹塑性反应。结果表明:采取抗震加强措施后的结构能满足"大震不倒"的抗震性能要求。     

复杂高层建筑抗震与消能减震研究进展

复杂高层建筑的震害在近来的历次地震中都有发生,其抗震分析和设计难度较大,提高其抗震性能是当前建筑抗震的难点之一。通过对近10年来国内在复杂高层建筑抗震方面的研究进行回顾和总结,重点介绍了组合剪力墙及筒体结构、钢管混凝土结构、结构模型振动台试验和三种消能减震方法。提出了采用新型高效的结构体系及高性能抗震部件或消能减震新技术改善复杂高层建筑抗震性能。这些研究工作与工程实践紧密结合,大部分研究成果已在实际工程中成功应用。图18参28     

Seismic behavior of multistory RC building frames with vertical setback irregularity

This paper is the second of two companion papers that aimed to examine the behavior of irregular buildings subjected to seismic excitation. In the present study, seismic response of the building frames with setback irregularity has been determined. To achieve this purpose, building frames with different geometrical configurations of setbacks are modeled and analyzed using nonlinear dynamic analysis by subjecting them to an ensemble of 27 ground motions to generate 21 060 nonlinear dynamic analysis results. These results are compiled to create a seismic response database consisting of parameters such as maximum roof displacement, maximum interstory drift ratio, maximum plastic hinge rotation and collapse risk parameters. Furthermore, nonlinear regression analysis is conducted on this database to propose simple equations to estimate the seismic response parameters. Finally, the proposed equations are validated for two‐dimensional and three‐dimensional building models, and applicability of the proposed equation in performance‐based and displacement‐based designs is briefly discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

南京地质博物馆结构设计

南京地质博物馆扩建工程是一个超限复杂的高层建筑,该工程同时具有平面、立面不规则特性,特别是跨度达49 m的裙房部分为复杂悬挑结构。工程采用钢桁架和钢筋混凝土框架剪力墙混合结构形式,详细介绍了该工程的结构概念设计及结构布置原则,结构静力、动力特性分析,竖向地震作用以及弹塑性分析等,介绍了如何运用性能化设计方法对不同结构部位和构件所作的加强。相关内容可为具有类似复杂结构的工程设计提供参考。     

中美超限高层建筑性能化抗震设计方法对比分析

为了系统比较中美超限高层建筑基于性能的抗震设计方法,介绍了美国太平洋地震工程研究中心主导实施的“高层建筑推进计划”项目,探讨了该项目的主要成果（PEER-2010）《高层建筑基于性能的抗震设计指南》,并结合算例将其建议的基于性能抗震设计方法与中国GB 50011-2010《建筑抗震设计规范》和GB 50010-2010《高层建筑混凝土结构技术规程》中规定的基于性能抗震设计方法进行对比。研究结果表明:PEER-2010与我国规范中分别建议的超限高层建筑性能化抗震设计方法在性能目标划分、地震动选择、荷载输入及对地基与结构相互作用的考虑上均存在差异。PEER-2010对性能目标的划分相对更宽松,建议的下一代选波方法能够考虑长周期超高层建筑的选波问题,并对考虑地基与上部结构相互作用有着较为明确的规定。     

解析高层建筑结构抗震超限设计

由于大多数高层建筑的结构特点已经超出了我国有关建筑工程的规定,因此在其建设过程中暴露出许多问题,抗震设计问题首当其冲。高层建筑抗震问题不仅关系到建筑物的使用寿命与安全,而且还会影响高层建筑行业的发展。对此,本文重点解析了高层建筑结构抗震超限设计。     

用新规范设计混凝土结构需注意的若干问题

针对新版混凝土结构设计规范、建筑抗震设计规范 (混凝土结构部分 )、高层建筑混凝土结构技术规程的内容 ,结合实际设计工作中的若干体会 ,对新旧规范的主要区别进行了阐述 ,供工程设计人员熟悉和掌握新规范时参考