Analytical investigation of response modification (behaviour) factor,R, for reinforced concrete frames rehabilitated by steel chevron bracing

Steel bracing of reinforced concrete (RC) frames has received noticeable attention in recent years as a retrofitting measure to increase the shear capacity of the existing RC buildings. In order to evaluate the seismic behaviour of steel-braced RC frames, some key response parameters, including the ductility and the overstrength factors, should first be determined. These two parameters are incorporated in structural design through a force reduction or a response modification factor. In this paper, the ductility and the overstrength factors as well as the response modification factor (or seismic behaviour factor) for steel chevron-braced RC frames have been evaluated by performing inelastic pushover analyses of brace-frame systems of different heights and configurations. The effects of some parameters influencing the value of behaviour factor, including the height of the frame and share of bracing system from the applied lateral load have been investigated. It is found that the latter parameter has a more localised effect on the R values and its influence does not warrant generalisation at this stage. However, the height of this type of lateral load-resisting system has a profound effect on the R factor, as it directly affects the ductility capacity of the dual system. Finally, based on the findings presented in the article, tentative R values have been proposed for steel chevron-braced moment-resisting RC frame dual systems for different ductility demands and compared with different type of bracing systems.     

门式刚架轻钢结构支撑体系计算方法的探讨

分析比较门式刚架轻钢结构的支撑计算的三种方法，对支撑体系的计算提出合理的方案。     

钢筋混凝土圆环支撑系统在深基坑设计与施工中的应用

由于城市发展不断往地下空间延伸,周边环境复杂、临坑建筑密集、开挖深度大的基坑越来越多。钢筋混凝土圆环支撑由于结构受力合理、位移变形较小、方便土方开挖等优点,在城市特大深基坑支护工程中应用日益广泛。结合笔者多年基坑支护设计与施工的工程实际经验,本文分析了钢筋混凝土圆环支撑在设计和施工过程中应注意的问题,如支撑刚度、角部支撑布置、支撑立柱计算、支撑结构裂缝处理和支撑结构静爆拆除等;探讨了实际钢筋混凝土圆环支撑基坑案例中位移计算结果与监测数据存在一定差别的原因。希望文中的经验总结能给基坑工作者在深基坑内撑支护结构设计与施工提供一定的参考价值。     

钢框架梁柱节点抗震性能研究

利用有限元软件ANSYS对四种节点进行了抗震性能计算分析,结果表明：在反复荷载作用下,构造改进节点抗震性能好,能够满足我国抗震规范的要求,极限状态时,塑性铰外移,避免节点的脆性断裂。     

Analytical expressions for preliminary design of dissipative bracing systems in steel frames

In this paper a direct displacement-based design (DDBD) method for seismic design of steel frames equipped with dissipative braces is proposed. Attention is focused on concentric braced steel frames with pinned beam-to-column joints in which the bracing system (with viscoelastic or elastoplastic dissipative devices) is the main seismic resistant component. The proposed design method uses an equivalent continuous model where flexural deformability and shear deformability are related respectively to columns and diagonals of the bracing system. In this way, analytical expressions of the required flexural and shear stiffness distributions are obtained. These expressions are quite simple and can be conveniently used in preliminary design of dissipative diagonal braces and columns. Examples are shown for steel frames with dissipative braces based on elastomeric dampers (viscoelastic devices) and steel frames with buckling-restrained braces (elastoplastic devices). Results of time history analyses are illustrated and discussed in order to evaluate the effectiveness of the proposed DDBD procedure.     

论述型钢混凝土在实际工程中的应用

介绍了在海口高烈度地区工业主厂房使用型钢混凝土组合结构的实际案例,通过结构分析计算,较为深入地探讨了采用型钢混凝土的原因,以及型钢混凝土结构的力学特点及优势,并针对在具体施工过程中遇到的问题和解决经验进行了详细的阐述。     

钢纤维高性能混凝土框架节点的延性分析

根据试验对钢纤维混凝土框架梁柱节点的延性进行研究,分析了梁柱节点的破坏形态及节点抗剪强度和延性性能,基于试验结果提出了考虑钢纤维、混凝土、箍筋,共同作用的节点承载力计算方法。     

某多层RC框架和支撑—钢框架抗震性能分析

结合工程实例,采用软件SAP2000对RC框架和支撑—钢框架结构抗震性能进行了抗震性能分析,结果表明:支撑—钢框架侧移刚度要大过RC框架,在罕遇地震作用下出现塑性铰少,优化支撑后的钢框架,地震能量绝大部分被支撑所耗散。     

钢框架栓焊梁柱连接节点的抗震设计

节点设计是整个钢结构设计的重要环节,提高钢框架梁柱连接节点的抗震性能是整个钢结构抗震设计的重要内容.本文主要介绍了提高钢框架栓焊梁柱连接节点的抗震设计的主要措施,主要方法包括:通过加腋和加盖板对节点进行加强,提高节点承载力;对梁局部削弱,使塑性铰从节点区外移至梁上;改进节点区焊接孔构造形式,缓解局部应力集中;妥善处理弧板和垫板,减少焊缝缺陷.     

Strength of flexibly connected steel frames

An analytical study of the strength of flexibly-connected steel frames is presented. A computer program which includes the effects of material and geometric nonlinearities of members and connections is developed, and used in a parametric study which indicates that in most cases, increased connection stiffness leads to an increase of frame strength, but in exceptional cases, it may result in a slight loss of strength.     

型钢混凝土结构的抗震性能

指出型钢混凝土结构相对于混凝土结构和钢结构具有更好的耐久性、抗震性能等优点,是适于推广和应用的结构形式之一,重点介绍了型钢混凝土柱和型钢混凝土节点的力学性能,从而完善型钢混凝土结构的理论研究和抗震设计。     

轻型门式刚架结构屋盖纵向水平支撑的作用

通过对桌一轻型门式刚架轻型房屋钢结构工程加固改造案例的分析,阐述了屋面纵向支撑的作用。     

粘钢加固钢筋混凝土板抗裂性的分析

在截面应变、混凝土受压、钢筋应力应变基本假定的基础上，对粘钢加固钢筋混凝土板开裂弯矩的计算方法进行了分析，并与试验值进行了对比，误差基本满足工程精度要求。     

填充墙对钢框架结构抗震反应影响分析

运用SAP2000有限元分析软件对带填充墙钢框架结构进行模态分析和地震响应弹塑性时程分析。填充墙能与钢框架结构共同工作,并提高结构的整体强度和刚度。考虑填充墙体对结构抗侧力的有利作用,可以使结构设计更加符合真实的受力状态。在设计中应充分合理的考虑填充墙影响,才能使钢框架的抗震设计更加合理。     

Approximate formulae for natural periods of plane steel frames

Approximate formulae for determining by hand with a high enough accuracy the first three natural periods of vibration of plane steel unbraced and braced frames are provided. These formulae are based on the modeling of a plane steel frame as an equivalent cantilever beam for which analytical expressions for the natural periods are available. Extensive parametric studies involving the finite element computation of the first three natural periods of 110 plane steel unbraced and braced frames are employed to establish correction factors for the equivalent beam modeling formulae which are functions of the number of stories and bays of the frame. The resulting corrected formulae permit a highly accurate determination of the first three natural periods of plane steel frames.     

On the concept of earthquake resistant hybrid steel frames

The concept of hybrid steel frame system is presented in which mixtures of fully-rigid and semi-rigid steel connections are used in the 9 and 20-story SAC frames. Several different patterns and locations of semi-rigid connection replacements within the frame are examined in order to identify the hybrid frames with most energy dissipation capabilities. Inelastic dynamic analyses are conducted on the proposed selected frames by subjecting them to the Los Angeles earthquake records characterized as those with 10% probabilities of exceedance in 50 years and 2% probabilities of exceedance in 50 years. The maximum story drift for the hybrid frames are determined and compared to the “life safety” and “collapse prevention” limits as recommended by the FEMA 356. The roof-displacement time history, story drift, and member forces for the hybrid frames are reported and compared with those of conventional SAC frames without semi-rigid connections.     

钢骨混凝土在地震区的应用概述

简单介绍了钢骨混凝土的定义、特点及应用,论述了钢骨混凝土在地震区的使用情况,分析了钢骨混凝土抗震性能的影响因素,指出了钢骨混凝土抗震性能研究存在的问题,对促进钢骨混凝土在地震区的应用具有一定指导作用。     

浅谈钢骨混凝土结构的应用与发展

简述了钢骨混凝土的发展，列举了钢骨混凝土结构在日本及我国的应用实例，介绍了钢筋混凝土结构的承载力、变形能力、防火能力等方面的特点，指出该结构的工程应用将越来越广泛。     

一种新型混凝土异形柱--型钢混凝土异形柱的概念体系初探

针对型钢混凝土异形柱体系特点,对相关问题进行了评述,分析其特点及具有的优越性和应用前景,并提出了若干需要研究解决的问题.     

钢骨混凝土结构的研究进展综述

介绍了钢骨混凝土结构的形式与特点,详细叙述了国内、外钢骨混凝土的发展概况,并介绍了钢骨混凝土结构在工程中的应用情况,最后对钢骨混凝土结构的发展进行了展望,指出钢骨混凝土结构具有良好的抗震性能,值得推广使用。