细腰复杂截面高层建筑抗震性能分析

使用PMCAD软件,通过某模型工程对细腰复杂截面高层建筑结构的抗震性能进行了分析.结果显示细腰的程度越大,结构整体抗震性能越差.认为细腰平面做为组合平面的一种,在所列三项及三项以上不规则高层建筑做为其中一项进行控制,而不单独做为一项进行控制较为合理.     

超限高层建筑工程数据库及Bayes知识发现

针对上海市超限高层建筑工程实例,收集整理了相关设计信息,构建了能够表征这些设计信息的数据表并形成了数据库。鉴于传统的管理信息系统不能够空间表示,提出了一种新型的基于Arc-GIS的信息系统,同时引入了贝叶斯网络,以数据库样本为基础进行结构选型。实践证明,该系统充分利用了计算机的存贮、计算、统计、共享以及空间显示功能,贝叶斯网络为超限高层建筑结构体型优选提供了一种新的方法,对超限高层建筑工程的设计改进和规范的完善都具有一定的实际意义。     

超限高层建筑结构抗震设计加强措施和建议——以某超限高层建筑为例

为加强超限高层建筑结构的抗震性能,最大程度减小地震损失,以某一超限高层建筑为对象,对其结构抗震设计的加强措施和建议进行详细分析。在小震作用下运用pkpm软件MIDAS/Building对建筑结构进行弹性计算对比分析,证明弹性计算的可靠性;借用SATWE对结构在中震或大震作用下不同构件的承载力和截面进行验算;采用midasbuilding软件对该超限高层建筑进行罕遇地震作用下的静力弹塑性分析。根据不同震级下建筑结构线弹性分析结果,对建筑主体结构、结构抗震和地基基础进行加强设计,从中归纳出整体结构的抗震加强措施和建议,说明该超限结构能满足规范的设防要求,是安全可靠的。     

高层抗震结构造价的改进控制模型研究——基于一恢复重建高层的实例分析

采用WSR模型分析建筑工程抗震结构造价控制问题时,存在造价控制效果差的弊端。通过设计的高层建筑工程抗震结构造价控制模型构建造价控制的递阶层次结构,获取高层建筑工程造价控制的多种方案,从多种方案中通过三标度法和权重向量法获取造价控制的最优方案;另外采用质量量化QoS调度方法进行高层建筑工程造价效益控制约束均衡设计,以获取最优方案中高层建筑工程抗震结构造价控制的结果。实验结果表明,所设计模型可有效分析高层建筑的质量化特征,可改进控制高层抗震结构工程造价,预估消耗成本可控制在1.8万元以下,且分析耗时均值为0.15 h,具有节省成本和效率快的优势,控制效果较好。     

带加强层超高层建筑结构基于能力谱法的抗震设计

带加强层结构在加强层处的刚度发生剧变,从而引起侧向荷载下结构内力分布及变形的相应变化,地震作用下此类结构容易形成薄弱层,因而抗震性能较差。同时,带加强层的建筑物很多属于超限复杂高层建筑结构,无法直接套用规范方法进行抗震设计。根据带加强层高层建筑结构的受力变形特点及国内外研究者的研究成果,结合模态推覆分析理论和能力谱抗震设计方法,本文对带加强层高层建筑结构的受力变形性能作了详细的分析,提出此类结构基于能力谱法的抗震设计方法。此法采用受力层间侧移角作为性能指标,并针对加强层和普通楼层采用了不同的性能水准量化值,根据结构特点以底部和加强层上部两层楼作为薄弱层进行验算,最后通过算例验证所提方法的可行性。     

强震后高层建筑结构变形监测精度提高的研究

为解决强震作用后倾斜高层建筑结构监测存在的精度低、用时长等问题,提出高精度强震作用后倾斜高层建筑结构形变监测方法。通过确定回归平面强震后倾斜高层建筑结构的法线倾斜值、倾斜角与倾斜方向,来确定强震作用后倾斜高层建筑结构形变情况,完成强震作用后倾斜高层建筑结构的形变监测。使用BXJC 1.0软件进行建筑高层建筑形变模拟实验,在建筑高层附近设定四个基准点,基于建筑高层的底部每个立柱中近似等高方位设定16个形变监测结构点,实验发现:所提方法监测误差小精度高,监测误差最大值为0.05%,且监测用时较短,证明此方法进行监测的可行性。     

高层建筑桁架转换层地震反应线性分析方法研究

为探究高层建筑桁架转换层地震作用下的动力反应情况,采用SAP2000程序中平面壳单元和杆系单元对高层建筑桁架转换层进行有限元建模,采用模态分析法和地震反应谱分析法对高层建筑桁架转换层结构进行地震反应分析,结果表明:高层建筑中桁架转换层前8阶振型对自振周期影响较大,分析高层建筑桁架转换层地震作用反应时,主要采用前8阶振型振型,且桁架转换层及其上、下层间容易出现层间位移角突变现象,桁架转换层极易发生位移集中,是高层建筑的脆弱部分,应加强高层建筑桁架转换层设计,提升建筑安全性。     

框架填充墙结构被动控制抗震加固分析

针对不满足抗震性态目标的一栋四层钢筋混凝土框架填充墙结构,基于框架和填充墙的抗震性态目标,采用附加阻尼器的被动控制方法进行抗震加固分析研究。首先,提出两种被动控制加固方案:1.在一层所有填充墙平面内方向上并联阻尼器进行抗震加固;2.在一层和二层所有填充墙平面内方向上并联阻尼器进行抗震加固;其次,基于Open Sees有限元软件,建立上述两种被动控制加固方案的有限元模型,选取El Centro、Parkfield和San Fenando三条地震动进行罕遇地震作用下的地震反应分析;最后,依据使用功能为钢筋混凝土框架填充墙结构抗震性态目标的量化指标,即综合考虑层间位移角限值和填充墙破坏情况,判定四层钢筋混凝土框架填充墙结构采用加固方案二可满足抗震性态目标的要求。     

弯折断层系统上超剪切破裂传播的产生条件

断层的破裂速度是描述地震震源过程的重要物理量.如果震源破裂的传播速度超过剪切波速,将会对地震波场产生影响,造成更大的破坏性.超剪切破裂的产生受多种因素影响,断层的几何形状是因素之一.本文针对弯折断层的情况,采用三维空间非结构化网格的边界积分方法计算参数空间中的破裂相图,从中分析超剪切破裂的产生条件.以15°、25°和40°为例,得到了不同断层弯折角度的破裂相图.在本文的初始应力设置下,通过对不同的无量纲化临界滑动弱化位移Dc和初始剪应力Te参数组合的结果进行交叉对比发现,对于弯折面处于压缩区的断层模型,不可持续传播的自发停止破裂的发生条件与弯折角无关.而对于可持续传播破裂,其在平面断层的传播速度也不受弯折角影响;在弯折部分,随弯折角度增大,破裂传播速度越小,正应力越大,破裂强度越大,破裂越难以越过弯折交界线继续传播(如40°).对比三个不同弯折角的相图,弯折角越小,越容易发生超剪切破裂,即发生超剪切的参数空间越大.同时,随着初始剪应力的增大,超剪切不仅可以发生在弯折面上,甚至在平面部分就可以发生.总体而言,Dc较小、Te较大时,破裂传播速度更大,更容易形成超剪切破裂.另外,因克服弯折交界处的正应力而产生的错位延迟效应也与弯折角度正相关.     

基于性能的设计方法在超限高层建筑结构设计中的应用研究

针对超限高层建筑结构抗震设计,提出了基于性能设计方法的性能目标,通过结构在小震、中震、大震作用下的弹性、弹塑性静力和动力时程分析,对三水准地震作用下结构构件进行了承载力定量分析。从理论上证明了结构性能可以达到“小震不坏,中震可修,大震不倒”的抗震设防目标,同时进行了1：20模型的结构振动台试验,确证了实际结构设计的安全性。     

Code design provisions for torsionally coupled buildings on elastic foundation

The effectiveness of the design recommendations made by various major building codes to account for torsional coupling effects is evaluated with respect to the parametric responses to earthquake ground motion of a simple single-storey asymmetric building model supported on an elastic foundation. The objectives are to determine the extent to which the response trends observed in previous studies of asymmetric rigidly based buildings are affected by changes in the flexibility of the foundation medium and to comment on and suggest necessary amendments to the design recommendations in order that suitable allowance be made for the resultant changes in the magnitude of torsional coupling effects. It is concluded that whilst the qualitative effects of torsional coupling are not affected by soil–structure interaction, their magnitude depends significantly on the frequency content of the free-field motion. The response to the El Centro earthquake record is conservatively accounted for by assuming the structure to be supported on a rigid foundation. An allowance for increased response effects due to soil–structure interaction is suggested for incorporation in the torsional design recommendations when European earthquake records are employed.     

不规则高层结构基于新型电磁惯性质量阻尼器的半主动控制

为了研究新型电磁惯性质量阻尼器(Electromagnetic Inertial Mass Damper,EIMD)应用于偏心高层结构振动控制工程的可行性,鉴于半主动控制技术的优点,基于LQR主动控制算法,提出一种可行的EIMD-偏心高层结构半主动控制策略,同时研究EIMD在结构每层中安装位置不同对于控制偏心高层结构扭...     

平面不规则基础隔震结构抗扭设计研究

针对平面不规则结构在水平地震作用下的振动特性,通过调整隔震层隔震支座的布置,得到3种不同工况的隔震层刚心与上部结构质心、刚心相对位置关系,分别以楼层位移和层间位移为指标的扭转位移比,作为平面不规则基础隔震结构扭转响应指标,利用弹塑性时程分析方法,通过对3种不同工况的扭转指标对比分析研究,提出适用于平面不规则基础隔震结构的抗扭设计方法。结果表明：对于平面不规则结构,应在保证隔震层扭转位移比小于1.2的基础上,使隔震层的刚心和上部结构的刚心分别位于上部结构质心的两侧,可有效控制上部结构的扭转。     

Parametric earthquake response of torsionally coupled buildings with foundation interaction

A study is made of the effect of soil-structure interaction on the coupled lateral and torsional responses of asymmetric buildings subjected to a series of historical free-field earthquake base motions. It sh shown that for particular classes of actual buildings the equivalent rigid-base responses are significantly increased for structures founded on medium-stiff soils, and hence the assumption of the major building codes that a conservative estimate of response is obtained by considering the structure to be fixed rigidly at its base is shown to be inconsistent with the presented dynamic results. It is shown that foundation interaction produces greatest amplification of torsional coupling effects for structures subjected to a particular class of European strong-motion earthquake records, identified by similarities in their spectral shape, for which the vibrational energy of the ground motion is distributed approximately uniformly over the range of frequencies which are of interest for real structures. It is recommended that provision be made in the torsional design procedures of building codes for the increase in the coupled torsional response due to soil-structure interaction as indicated in this study. Such provision should be based on the results of comprehensive parametric studies employing a wide selection of earthquake records and accounting for expected variations in localized soil conditions.     

Alternative method to locate centre of rigidity in asymmetric buildings

Response of asymmetric buildup under earthquake excitation often involves lateral vibration coupled with torsional vibration. Floor slab is, in general, assumed as rigid along the in‐plane direction. Building code provisions to account for the torsional effect in static force procedure are based on centre of rigidity or shear centre of the building. A convenient procedure is developed here to locate the centre of rigidity or shear centre, which can be implemented, using any standard building analysis software. The procedure is applicable for orthogonal as well as non‐orthogonal building systems and accounts for all possible definitions of static eccentricity to compute the design response. An irregular building is analysed to illustrate the proposed methodology. Significant variation in member force resultants is observed due to different definitions of static eccentricity. Finally, a mathematical proof is presented to substantiate the applicability of the proposed procedure to a non‐orthogonal building. Copyright © 2006 John Wiley & Sons, Ltd.     

Evaluation of code torsional provisions by a time history approach

Presented in this paper is a detailed parametric study of the coupled lateral and torsional response of single-storey building models subjected to earthquake base loadings. The aim is to assess the influence of torsional coupling on the elastic responses of buildings subjected to transient ground motion records, and to make comparisons with current code provisions which make allowance for coupling effects by means of empirical design procedures. The study of building responses to selected earthquake excitations shows that the qualitative effects of the controlling parameters on the maximum translational and torsional responses of the coupled system are similar to those observed in analyses using idealized response spectra to represent the input ground motion. It is also demonstrated that for particular ranges of the key parameters defining the structural system, typical of the properties of many actual buildings, torsional coupling induces significant amplification of earthquake forces. This amplification is shown to be inadequately accounted for in the current design provisions of major building codes. Recommendations for improving existing design practice for asymmetric structures are outlined.     

Accidental torsion due to overturning in nominally symmetric structures isolated with the FPS

Overturning of a structure causes variations in the normal loads of the isolators supporting that structure. For frictional isolators, such variation leads to changes in the frictional forces developed and, hence, in the strength distribution in plan. For frictional pendulum system (FPS) isolators, it also causes changes in the pendular action, i.e. in the stiffness distribution of the isolation interface. Therefore, although the structure is nominally symmetric it develops lateral–torsional coupling when it is subjected to two horizontal components of ground motion. This coupling is denoted herein as accidental torsion due to overturning, and its effect in the earthquake response of nominally symmetric structures is evaluated. Several parameters are identified to control this coupling, but the most important are the slenderness of the structure and the aspect ratio of the building plan. Results are presented in terms of the torsional amplification of the deformations of the isolation base and the interstorey deformations of the superstructure. The FPS system is modelled accurately by including true large deformations and the potential uplift and impact of the isolators. Impulsive as well as subduction‐type ground motions are considered in the analysis, but results show small differences between them. An upper bound for the mean‐plus‐one standard deviation values of the torsional amplifications for the base due to this accidental torsion is 5%. This implies that for design purposes of the isolation system such increase in deformations could probably be neglected. However, the same amplification for the interstorey deformations may be as large as 50%, depending on the torsional stiffness and slenderness of the superstructure, and should be considered in design. In general, such amplification of deformations decreases for torsionally stiffer structures and smaller height‐to‐base aspect ratios. Copyright © 2003 John Wiley & Sons, Ltd.     

Evaluation of dynamic eccentricities obtained using a probabilistic approach,response spectrum methods and modern building codes

In this paper a probabilistic approach has been adopted to study both the effects of uncertainty in earthquake frequency content and the correlation between earthquake frequency content and ground motion intensity on the response of a single-storey torsionally coupled elastic structure. The earthquake ground motion has been assumed to be a Gaussian, zero mean, stationary random process which is fully characterized by a power spectrum. The ground acceleration power spectrum is idealized as a probabilistic normalized power spectrum computed from actual earthquake records. The advantage of such an idealization is that it enables the effect of the natural frequency as a controlling structural parameter in torsional coupling to be assessed. Comparisons of the dynamic amplifications of eccentricity with those obtained from modern codes of practice and conventional response spectrum analyses have been made. The results of this study have shown that the variation in the frequency content has a significant effect on the response of low frequency structures, while the correlation between the frequency content and the intensity of seismic ground motion is insignificant for the wide range of structures considered. The structure natural frequency has been shown to be an important controlling parameter in the torsionally coupled response of structures subject to seismic loading. The frequency dependence of the dynamic amplification of eccentricity was found not to be reflected in the response spectrum analysis and the torsional provisions of modern building codes.     

使用偏心支撑减小不规则高层建筑的扭转振动效应

文章对比分析了一个不规则高层钢筋混凝土框-剪结构和在原结构基础上增设偏心支撑后的新结构的抗震性能,比较了它们的自振特性以及层间位移等地震作用效应。针对不规则高层建筑在地震作用下不可避免的扭转振动问题,提出在结构中适当地增设偏心支撑来减小结构的扭转振动效应及其它结构地震反应这种简单可行、经济适用的方法。