伸臂特性对框-筒结构中加强层力学性能的影响

本文根据伸臂结构的简化模型和伸臂与外框柱的变形协调条件,考虑伸臂的实际刚度,导出伸臂对核心墙的附加力矩,求得结构顶点侧移。对伸臂位置及刚度变化引起的侧移变化与内力突变进行了分析,结合工程分析结果对高层建筑加强层设计提出了一些参考意见。     

超高层巨型管柱桁架加工制作技术

巨型管柱桁架主要是伸臂桁架、腰桁架,在外框柱与核心筒之间设置伸臂桁架可减小结构侧移,通过提高水平荷载作用下的外框架柱的轴力,增加框架承担的倾覆力矩,同时减小了内核心筒的倾覆力矩。对于框架核心筒结构,设置伸臂桁架后侧移减小显著;而对于筒中筒结构而言,侧移减小的效果不明显。在结构周围设置腰桁架可使各框架柱承受的轴力均匀变化,因此也可以达到提高外框架抗倾覆力矩的能力以及减小侧移的目的。超高层建筑结构可以根据具体情况,同时设置伸臂桁架和腰桁架。     

带加强层框—筒结构中水平伸臂最佳刚度研究

利用带水平伸臂的框架-筒体结构侧移公式,对带加强层的框架一筒体结构水平伸臂的最佳刚度进行了分析,明确给出了根据需要减少的结构侧移量,确定水平伸臂最佳刚度的方法,并给出了具体参数.本文的结论,可供工程设计特别是确定结构方案时参考使用.     

伸臂结构在超高层中的分析

伸臂结构能有效减小高层建筑的侧移和核心筒的弯矩，本文介绍对此所做的力学分析与计算推导。     

黏滞阻尼器伸臂桁架布置对超高层结构减震性能影响研究

在超高层结构中,传统伸臂桁架能显著提高结构抗侧刚度、减小结构侧移,但给结构带来刚度、内力突变等不利影响,形成结构薄弱层。黏滞阻尼器伸臂桁架因其在一定程度上减小结构刚度、提供附加阻尼比,成为近年高层建筑结构抗震与抗风的新型体系。针对一226 m超高层结构中某一榀平面框架-剪力墙,在伸臂桁架中布置黏滞阻尼器,对比分析5种不同黏滞阻尼器布置方案伸臂桁架结构在多遇地震、设防地震和罕遇地震作用下的消能减震效果,将为黏滞阻尼器在超高层结构伸臂桁架中的进一步研究和应用提供借鉴。     

超高层建筑结构中伸臂桁架的设计实践

基于对多个超高层项目中伸臂桁架进行的深入研究,提出伸臂桁架数量与塔楼高度之间的近似关系,指出将伸臂桁架设置在0.5H~0.9H区段楼层时可有效减小结构侧移,设置在0.3H~0.7H区段的楼层时可更好地控制结构自振周期,设置在0.3H以下的楼层时可有效减小底部楼层核心筒墙肢的拉应力。并介绍了伸臂桁架的常用形式,根据其抗侧效果的不同给出了对应的适用条件;分析了伸臂桁架与核心筒墙体和框架柱的连接节点方式,提出相关设计建议;指出应注重研究伸臂的合拢时间,以控制内外筒沉降差对结构的不利影响,确保塔楼施工过程中的安全性。     

地震作用下环带对带伸臂的框-筒结构力学性能的影响

对一60层的框架核心简结构通过改变水平伸臂、环带构件的设置情况而形成不同的结构方案,采用三维有限元分析软件ETABS进行地震作用下的动力分析,探讨地震作用下水平伸臂以及不同刚度环带对结构顶点侧移、核心筒剪力、外框柱轴力的影响。分析表明：环带的设置、环带本身的刚度对地震作用下高层框架一核心筒结构的顶点侧移影响不大;但环带能有效调整外框柱的轴力分布,更好的发挥外框柱的整体作用;环带的设置会加大水平加强层的剪力突变这一现象。     

某超高层建筑加强层伸臂桁架选型分析

超高层结构往往利用建筑设备层或避难层设置伸臂结构,以协调核心筒与外框架的变形,提高结构的抗侧刚度。通过对K型与X型伸臂桁架的分析,研究了两种伸臂桁架的杆件布置形式对其效率的影响规律,并对比了两种伸臂桁架的效率优劣。     

超高层建筑结构加强层耗能减震技术及连接节点设计研究

在框架-核心筒结构体系中,加强层可显著提高结构抗侧刚度、减小结构侧移,但会带来结构刚度、内力突变等不利影响。以某超高层建筑为工程背景,研究了黏滞阻尼器在伸臂桁架体系中的应用及在多遇地震和罕遇地震作用下的减震效果,研究了设置黏滞阻尼器的环带桁架在超高层建筑中的较优位置和减震效率。结果表明：黏滞阻尼器在伸臂桁架结构中的设置可以减小核心筒剪力墙的塑性损伤,减小结构的动力响应;设置黏滞阻尼器的环带桁架宜布置在层间相对速度大的位置,随超高层结构高度增加,阻尼器的减震效率降低。通过对伸臂桁架与外框柱、核心筒连接节点的设计及构造的分析,提出了连接节点的设计建议。     

南宁华润中心东写字楼桁架层施工技术

南宁华润中心东写字楼为典型的钢混凝土核心筒+外框钢结构的超高层结构体系。伸臂桁架层减小结构侧移在超高层结构中的重要性不言而喻。然而伸臂桁架层结构复杂,构件繁多,对超高层的施工管理和施工工艺提出很大挑战。针对桁架层施工,介绍结合BIM技术的钢结构安装、顶模改造协同、土建施工优化等关键施工技术,总结超高层伸臂桁架层施工经验。     

具有外伸臂超高层结构的水平位移计算

以设置四道外伸臂超高层结构为例，探讨了带外伸臂超高层建筑结构的水平位移计算问题。导出了求解外伸臂约束弯矩的矩阵方程，在此基础上推导了求解顶点水平位移的计算公式，同时探讨了外伸臂抗弯刚度的计算问题。最后给出了算例，说明外伸臂的有效性和计算方法对工程设计的实用性。     

位移放大型黏滞阻尼伸臂桁架减震效果及动力试验研究

为提高黏滞阻尼伸臂桁架在地震作用下的耗能效率,设计了一种带位移放大装置的黏滞阻尼伸臂桁架。对分别设置传统型和位移放大型黏滞阻尼伸臂桁架的超高层结构进行有限元分析,对比了结构的地震响应及阻尼器的工作状态。通过动力荷载试验,考察两种黏滞阻尼伸臂桁架的滞回性能,对比阻尼器的位移及耗能,研究位移放大系数的变化规律,分析伸臂桁架刚度对黏滞阻尼伸臂桁架工作效率的影响。结果表明：相比传统型黏滞阻尼伸臂桁架,采用位移放大型黏滞阻尼伸臂桁架可将阻尼器的耗能效率提高至原来的1.5~1.8倍,使结构获得更好的减震效果;位移放大型黏滞阻尼伸臂桁架滞回曲线光滑、对称、饱满,具有良好的工作性能,且能有效放大阻尼器的工作位移并增大耗能;提出了黏滞阻尼伸臂桁架的位移放大系数的计算式,计算值与试验值吻合较好;为保证黏滞阻尼伸臂桁架的工作效率,建议伸臂桁架的刚度比取值不小于9。     

An analytical model for high‐rise wall‐frame structures with outriggers

In this paper, the governing equations of wall‐frame structures with outriggers are formulated through the continuum approach and the whole structure is idealized as a shear–flexural cantilever with rotational springs. The effect of shear deformation and flexural deformation of the wall‐frame and outrigger trusses are considered and incorporated in the formulation of the governing equations. A displacement‐based one‐dimensional finite element model is developed to predict lateral drift of a wall‐frame with outriggers under horizontal loads. Numerical static results are obtained and compared with previously available results and the values obtained from the finite element package MIDAS. The proposed method is found to be simple and efficient, and provides reasonably accurate results in the early design stage of tall building structures. Copyright © 2007 John Wiley & Sons, Ltd.     

Structural performance of multi‐outrigger‐braced tall buildings

The optimum designs of multi‐outriggers in tall building structures are presented and discussed in this paper, through the analysis of structural performance of outrigger‐braced frame‐core structures. The influences of the locations of outriggers and the variations of structural element stiffness on the base moment in core, top drift and fundamental vibration period of such tall building structures are analysed in detail. A non‐linear optimum design procedure for reducing the base moment in the core is presented based on the penalty function method. The computer programs are developed on the basis of the proposed methods for analysing the behaviour and optimum design of multi‐outrigger structures. A series of figures presented in this paper can be used for the design purposes of outrigger‐braced tall building structures. Copyright © 2003 John Wiley & Sons, Ltd.     

Reduction of vibration on a cantilever Timoshenko beam subjected to repeated sequence of excitation with magnetorheological outriggers

This paper deals with the statistical effects of an outrigger system on a cantilever beam under seismic excitation. The nonstationary random approach is employed to simulate seismic events. The Timoshenko beam approach is used to model the frame‐core tube linked at a point of its length by the damped outriggers, therefore are connected vertically two magnetorheological damper devices. The peak root‐mean‐square values of displacement responses is employed as a best measure effective to specify the optimal locations of outriggers according to different vibration modes. To evaluate the performance of the control system, the control algorithm based on Lyapunov stability theory is adopted to seek the input voltage leading to the reduction of vibration.     

A general solution for performance evaluation of a tall building with multiple damped and undamped outriggers

This paper presents a general solution for performance evaluation of a tall building with multiple damped and undamped outriggers. First, general rotational stiffness (GRS) is proposed to model an outrigger that consists of the stiffness of perimeter columns and an outrigger connection and the damping of dampers in an outrigger. By utilizing the dynamic stiffness method, the GRS can be represented by complex stiffness in an outrigger element. To analyze the dynamic characteristics of a tall building with multiple outriggers, a dynamic transcendental equation is obtained from the combination of the GRS and dynamic stiffness method. The structural responses can be calculated through the Fourier transform based on this equation. Moreover, the GRS can also be blended into a finite element (FE) model to generate an augmented state‐space equation for the analysis of the dynamic characteristics and structural responses. Applications to various outriggers are illustrated. In the numerical analysis, good agreements are found between the GRS and the FE that validates the proposed method, and the performances of various outrigger systems are evaluated parametrically. As the results of a tall building with multiple damped or undamped outriggers, the proposed method is capable of providing an optimally parametric design with respect to the position of outriggers, damping, and core‐to‐column and core‐to‐outrigger stiffness ratio. Copyright © 2015 John Wiley & Sons, Ltd.     

Analysis of outrigger‐braced reinforced concrete supertall buildings: Core‐supported and tube‐in‐tube lateral systems

This study is primarily focused on the approximate analysis of reinforced concrete outriggers which are commonly used in the design and construction of supertall buildings subject to distributed horizontal loads. Existing global analysis formulae that provide preliminary results for lateral deflections and moments are reviewed for two lateral load resisting systems, namely, core‐supported‐with‐outrigger (CSOR) system and less frequent tube‐in‐tube‐with‐outrigger (TTOR) system. These formulae are only applicable for CSOR and neglect the reverse rotation of the outrigger actually suffered due to the propping action from the outer columns and give rather high predictions of the deflections compared with advanced numerical finite element (FE) models. An improved model is proposed which overcomes this issue and provides more consistent results to FE predictions. The same can also be extended to TTOR. Several case studies are investigated to verify the accuracy of the proposed methodologies. The global analysis is followed by the local analysis of reinforced concrete outrigger beams using strut‐and‐tie modelling and non‐linear FE analysis to obtain optimized reinforcement layouts (reduction of quantities of reinforcement). The results highlight the different challenges in detailing such structural members which are heavily loaded (high congestion of reinforcement), and the behaviour at failure can be brittle.     

Analysis of outrigger numbers and locations in outrigger braced structures using a multiobjective genetic algorithm

Due to its advantages, the outrigger braced system has been employed in high‐rise structures for the last 3 decades. It is evident that the numbers and locations of outriggers in this system have a crucial impact on the performance of high‐rise buildings. In this paper, a multiobjective genetic algorithm (MGA) is applied to an existing mathematical model of outrigger braced structures and a practical project to achieve Pareto optimal solutions, which treat the top drift and core base moment of a high‐rise building as 2 trade‐off objective functions. MATLAB was employed to explore a multiobjective automatic optimization procedure for the optimal design of outrigger numbers and locations under wind load. In this research, various schemes for the preliminary stages of design can be obtained using MGA. This allows designers and clients easily to compare the performance of structural systems with different numbers of outriggers in different locations. In addition, design results based on MGA offer many other benefits, such as diversity, flexible options for designers, and active client participation.