Cursory seismic drift assessment for buildings in moderate seismicity regions

This paper outlines a methodology to assess the seismic drift of reinforced concrete buildings with limited structural and geotechnical information. Based on the latest and the most advanced research on predicting potential near-field and far field earthquakes affecting Hong Kong, the engineering response spectra for both rock and soil sites are derived. A new step-by-step procedure for displacement-based seismic hazard assessment of building structures is proposed to determine the maximum inter-storey drift demand for reinforced concrete buildings. The primary information required for this assessment is only the depth of the soft soil above bedrock and the height of the building. This procedure is further extended to assess the maximum chord rotation angle demand for the coupling beam of coupled shear wall or frame wall structures, which may be very critical when subjected to earthquake forces. An example is provided to illustrate calibration of the assessment procedure by using actual engineering structural models.     

基于性态的建筑工程抗震设计——《建筑工程抗震性态设计通则》述评

《建筑工程抗震性态设计通则(试用)》对抗震设计具有重要的指导意义,其中的抗震设计理念同以往的抗震设计规范在抗震设防的思路、概念和方法上有较大的区别。从工程实践的角度,比较了《通则》和现行抗震设计相关规范的区别并对具体应用提出一些看法。     

直接基于位移的结构抗震设计理论研究进展

直接基于位移的抗震设计是实现基于性能抗震设计思想的一条有效途径,其理论主要包括三方面的内容,即直接基于位移的抗震设计方法、位移需求估计方法和目标位移的确定。本文在阅读了大量文献的基础上,对国内外在这三方面的研究进行了介绍,并对今后的研究方向进行了展望。     

Simplified seismic performance assessment and implications for seismic design

The last decade or so has seen the development of refined performance-based earthquake engineering(PBEE) approaches that now provide a framework for estimation of a range of important decision variables,such as repair costs,repair time and number of casualties. This paper reviews current tools for PBEE,including the PACT software,and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore,proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed,highlighting needs for future research. To illustrate the potential of the methodology,performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework,applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations.     

Research on performance-based seismic design criteria

IntroductionAt present, the proper design and construction of buildings for earthquake-resistance is the most effective measure to mitigate the earthquake damage. In a broad sense, the earthquake resistance design should include the following seven contents:1) Determining the seismic design criteria Determining the seismic design goals3) Determining the seismic design parameters (intensity or ground motion) and their numerical values4) Determining the category of importance for buildings and …     

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。     

基于结构性能的抗震设计理论研究与展望

基于结构性能的抗震设计理论进90年代国际地震工程提出的新概念，是抗震设计理念上的一次变革。本文阐述了基于结构性能的抗震设计理论产生的背景，基本内容，主要特点及发展概况，并结合我国抗震设计理论和实际的现状就其研究和应用前景进行了展望。     

RC框架结构抗震目标性能水平确定方法研究

在基于性能抗震设计中,要求实现多级设防,目的是使结构抗震设计不仅要保护生命安全,同时也要控制因结构破坏而带来的经济损失,使结构在整个生命周期内费用达到最小。但由于结构抗震设计中存在着大量的不确定因素,使得实现每个性能水平都是不确定的,因此,每个性能水平的目标可靠度究竟取多高才能达到设计要求,是目前抗震设计的一个基本问题。针对这一问题,将地震作用、自重荷载、材料强度等看作随机变量,分析了结构造价与失效概率之间的近似关系,明确了不同性能水平失效概率之间的合理比例关系,采用"投资-效益"准则,且控制人员伤亡率小于社会可接受水平,来确定结构的目标性能水平。以两个钢筋混凝土框架结构为例,说明了该方法的应用。     

延性需求谱在基于性能的抗震设计中的应用

基于性能的抗震设计理论涉及如何简便而合理地确定结构在指定强度地震下的弹塑性位移需求。本文给出了利用延性需求谱求解结构位移需求的一般步骤:借助模态Pushover分析将多自由度体系分解为几个非线性单自由度体系,以考虑各阶振型的影响;利用延性需求谱计算对应模态的等效单自由度体系的延性及位移需求,并以一定方式组合转化为多自由度体系位移需求。最后,通过算例分析表明:利用延性需求谱求解结构位移需求是一种具有一定精度可为工程接受的简便方法,在基于性能的抗震设计中具有较好的应用前景。     

Constant-ductility inelastic displacement ratios for displacement-based seismic design of self-centering structures

This paper focuses on constant-ductility inelastic displacement ratios of self-centering single-degree-of-freedom (SDF) systems with two different levels of energy dissipation capacity, in the presence of 5% viscous damping ratio. A statistical analysis is developed considering an earthquake database composed of 228 ground motions recorded in California with magnitudes greater than six and organized for NEHRP soil class, ground motion duration, and peak ground acceleration. The response of self-centering SDF systems with large variability of initial periods, ductility levels, and postyield stiffness ratios is investigated and compared with the responses of SDF systems with bilinear plastic, Clough, and Takeda hysteresis. The inelastic demand variation with soil class, initial period, postyield stiffness ratio, unloading stiffness degradation, ductility level, and hysteretic behavior is highlighted. Simple and conservative analytical estimates of constant-ductility inelastic displacement ratios for mean and 90th percentile values in terms of initial period, ductility level, and postyield stiffness ratio are proposed to allow the extension of the Displacement-Based Design via Inelastic Displacement Ratio (C_μDBD) to self-centering structural systems.     

结构分灾抗震设计:概念和应用

详细论述了结构分灾抗震设计的产生背景、设计思想、优化模型和基本原则,指出结构分灾设计是在分析基于投资—效益准则的结构抗震设计模型的基础上,对工程实践中一些成功经验的提炼和概括而形成的设计方法,工程领域中一些现行设计方法和措施就是分灾设计的具体应用。当工程师们待处理的问题必须考虑高度不确定性因素时,将分灾设计作为一种可能选用的设计理念,将有助于工程师们实现设计创新。分灾设计符合基于性能的抗震设计思想,可以方便地实现基于性能的设计。     

基于性能的框架结构抗震设计研究

对国内外基于性能的抗震设计研究成果进行了较系统的综述与分析,研究表明,基于性能的抗震设计能够对结构在未来可能地震作用下的性能进行有效的控制,使破坏和损失限定在可接受的范围内。在此基础上,本文还初步提出了钢筋混凝土框架结构基于延性的抗震设计建议。     

基于性能的结构抗震设计研究

介绍了结构抗震性能水准的划分、抗震性能目标的确定以及常用的基于性能的抗震设计方法。文中着重探讨了按延性系数进行结构性能抗震设计的方法和步骤，最后指出性能抗震设计方法今后的发展趋势。     

基于建筑性能的非结构构件抗震设计研究

针对非结构构件在地震中破坏的现象、震害情况,分析破坏原因,给出了非结构构件的抗震设防目标。基于建筑物性能的基本思想,给出了非结构构件的性能设计要求;讨论了非结构构件和附属设备的抗震设计计算原则。对建筑的非结构构件提出了相应的抗震设防技术措施,以提高其抗震能力。     

基于位移的概率极限状态设计

尽管近年来国内外学者提出了多种基于位移的抗震设计方法,但采用的与位移相关的反应谱大多是平均谱,设计过程可以看作是确定性的。基于位移的抗震设计应该建立在可靠度理论基础之上。利用作者在概率延性需求谱方面已有的研究成果和可靠度分析方法——验算点法,本文提出了根据基于位移的目标可靠指标直接进行结构设计的方法,并给出了设计流程图。为便于工程应用,在进行了大量分析计算之后,本文建议了基于位移的概率极限状态分项系数设计表达式,并确定了其中的分项系数。最后,本文对一8层框架结构采用建议的分项系数设计表达式进行了设计,并对有待于进一步研究的问题进行了简要分析。     

改进直接基于位移的钢筋混凝土框架结构抗震设计研究

直接基于位移法进行抗震设计时,最初结构的刚度和承载力均是未知的,设计中需假定预期设计结构的振型模式和由此得到的结构侧向地震力分布,这样的设计结果会产生一定的偏差.针对此问题,提出了改进直接基于位移的抗震设计方法,即首先初步设计结构,根据初设结构的振型模式等效单自由度体系,结合目标位移反向设计结构刚度,将设计结构的刚度与初设结构刚度比较,进行调整设计,最后进行承载力设计.程序中为减少迭代次数,定义了结构竖向刚度调整系数,用以简化结构弹性刚度的确定过程,从而实现设计结构在相应地震设防水准下满足预期位移的控制要求.最后通过算例证明了该方法具有一定的准确性.     

Constant-ductility strength demand spectra for seismic design of structures

In displacement-based seismic design, constant-ductility strength demand spectra （CDSDS） are very useful for preliminary design of new structures where the global displacement ductility capacity is known. The CDSDS can provide the required inelastic lateral strength of new structures from the required elastic lateral strength. Based on a statistical study of nonlinear time-history for an SDOF system, the mean CDSDS corresponding to four site conditions are presented and approximate expressions of the inelastic spectra are proposed, which are functions of the structural period and ductility level. The effects of site conditions, structural period, level of ductility, damping and post-yield stiffness of structures on CDSDS are also investigated. It is concluded that site conditions, ductility level and structural period have important effects on the CDSDS and damping, post-yield stiffness effects are rather complex and of minor importance. The damping, post-yield stiffness effects depend on both the level of ductility and the natural period of structures.     

一种直接基于位移的抗震设计方法

与传统基于力的抗震设计方法相比,基于位移的抗震设计方法更适合实现基于性能抗震设计。本文在若干文献的基础上,提出了一种直接基于位移的抗震设计方法。该方法建立在结构屈服位移可由几何尺寸确定的基础上,根据不同水平地震作用下的目标设计位移,计算相应的延性系数,采用一定的Rμ-μ-Tn关系建立相应的非线性反应谱,以二折线模型模拟结构的性能曲线,然后根据结构不同的目标位移以及对应的非线性反应谱确定相应的有效周期,从中选择最小值作为设计结构的有效周期,根据有效周期计算结构的刚度,然后乘以屈服位移得到结构的屈服强度。根据结构屈服强度以及结构的超强系数,得到结构的设计基底剪力。该方法避免了设计中采用迭代计算,且一次设计就可以完成多水平设防的目的。     

台湾及邻近地区地震活动间歇性的一些特征

从地震活动间隔时间的角度出发,结合1970～2003年台湾及邻近地区的地震活动,对其震级一最大间隔时间对数的关系进行了分析。从地震活动等待时间的角度出发,分析了地震活动次数百分比与等待时间的关系,最后简略地介绍了地震活动次数百分比等值线图的一些特征。