Seismic performance evaluation of steel frame-steel plate shear walls system based on the capacity spectrum method

This paper presents some methods that the standard acceleration design response spectra derived from the present China code for seismic design of buildings are transformed into the seismic demand spectra, and that the base shear force-roof displacement curve of structure is converted to the capacity spectrum of an equivalent single-degree-of-freedom （SDOF） system. The capacity spectrum method （CSM） is programmed by means of MATLABT.0 computer language. A dual lateral force resisting system of 10-story steel frame-steel plate shear walls （SPSW） is designed according to the corresponding China design codes. The base shear force-roof displacement curve of structure subjected to the monotonic increasing lateral inverse triangular load is obtained by applying the equivalent strip model to stimulate SPSW and by using the finite element analysis software SAP2000 to make Pushover analysis. The seismic performance of this dual system subjected to three different conditions, i.e. the 8-intensity frequently occurred earthquake, fortification earthquake and seldom occurred earthquake, is evaluated by CSM program. The excessive safety of steel frame-SPSW system designed according to the present China design codes is pointed out and a new design method is suggested.

Performance-based seismic design of nonstructural building components:The next frontier of earthquake engineering

With the development and implementation of performance-based earthquake engineering,harmonization of performance levels between structural and nonstructural components becomes vital. Even if the structural components of a building achieve a continuous or immediate occupancy performance level after a seismic event,failure of architectural,mechanical or electrical components can lower the performance level of the entire building system. This reduction in performance caused by the vulnerability of nonstructural components has been observed during recent earthquakes worldwide. Moreover,nonstructural damage has limited the functionality of critical facilities,such as hospitals,following major seismic events. The investment in nonstructural components and building contents is far greater than that of structural components and framing. Therefore,it is not surprising that in many past earthquakes,losses from damage to nonstructural components have exceeded losses from structural damage. Furthermore,the failure of nonstructural components can become a safety hazard or can hamper the safe movement of occupants evacuating buildings,or of rescue workers entering buildings. In comparison to structural components and systems,there is relatively limited information on the seismic design of nonstructural components. Basic research work in this area has been sparse,and the available codes and guidelines are usually,for the most part,based on past experiences,engineering judgment and intuition,rather than on objective experimental and analytical results. Often,design engineers are forced to start almost from square one after each earthquake event: to observe what went wrong and to try to prevent repetitions. This is a consequence of the empirical nature of current seismic regulations and guidelines for nonstructural components. This review paper summarizes current knowledge on the seismic design and analysis of nonstructural building components,identifying major knowledge gaps that will need to be filled by future research. Furthermore,considering recent trends in earthquake engineering,the paper explores how performance-based seismic design might be conceived for nonstructural components,drawing on recent developments made in the field of seismic design and hinting at the specific considerations required for nonstructural components.

Peak displacement patterns for the performance-based seismic design of steel eccentrically braced frames

Performance-based seismic design(PBSD) aims to assess structures at different damage states. Since damage can be directly associated to displacements, seismic design with consideration of displacement seems to be logical. In this study, simple formulae to estimate the peak floor displacement patterns of eccentrically braced frames(EBFs) at different performance levels subjected to earthquake ground motions are proposed. These formulae are applicable in a PBSD and especially in direct displacement-based design(DDBD). Parametric study is conducted on a group of 30 EBFs under a set of 15 far field and near field accelerograms which they scaled to different amplitudes to adapt various performance levels. The results of thousands of nonlinear dynamic analyses of EBFs have been post-processed by nonlinear regression analysis in order to recognize the major parameters that influence the peak displacement pattern of these frames. Results show that suggested displacement patterns have relatively good agreement with those acquired by an exact nonlinear dynamic analysis.

Ground Motion and Site Effects on Performance-Based Design

The objective of Performance-Based Earthquake Engineering （PBEE） is the analysis of performance objectives with a specified annual probability of exceedance. Increasingly undesirable performance is caused by increasing levels of strong ground motion having decreasing annual probabilities of exceedance. The development of this methodology includes three steps： （1） evaluation of the distribution of ground motion at a site; （2） evaluation of the distribution of system response; （3） evaluation of the probability of exceeding decision variables within a given time period, given appropriate damage measures. The work has taken a systematic approach to determine the impact of increasing levels of detail in site characterization on the accuracy of ground motion and site effects predictions. Complementary studies have investigated the use of the following models for evaluating site effects： （1） amplification factors defined on the basis of generalized site categories, （2） one-dimensional ground response analysis, and （3） two-dimensional ground response analysis for surface topography on ground motion. The paper provides a brief synthesis of ground motion and site effects analysis procedures within a Performance-Based Design framework. It focuses about the influence on the evaluation of site effects in some active regions by different shear waves velocity measurements Down Hole （D-H）, Cross Hole （C-H）, Seismic Dilatometer Marchetti Test （SDMT） and by different variation of shear modulus and damping ratio with strain level and depth from different laboratory dynamic tests for soil characterization： Resonant Column Test （RCT）, Cyclic Loading Torsional Shear Test （CLTST）.

Application of consequence-based design criteria in regions of moderate seismicity

Current design criteria and prineiples of earthquake engineering design are reviewed,including safety factors, probabilistic approach,and two-level and muhi-level functional design ideas.The modern multi-functional idea is discussed in greater details.When designing a structure,its resistance to and the intensity of the earthquake action are considered. The consequence of failure of the structure is considered only through a rough and empirical factor of importance,ranging usually from 1.0 to 1.5.This paper suggests a method of'consequence-based design,'which considers the consequences of malfunctioning instead of simply an importance factor.The main argument for this method is that damage to a structure located in different types of societies may have very different consequences,which are depeudant on its value and usefulness to the society and the seismicity in the region.

SELECTING CLUSTER MODEL IN Sn - BASED SOLDER ALLOY DESIGN WITH DV - X_α CALCULATION METHOD

Applying calculation method in alloy design should be an important tendency due to its characters of inexpensive cost, high efficiency and prediction. DOS calculations of AuSn, AsSn and SbSn Sn- based alloys have been investigated by employing DV - Xa method, in which different cluster models were adopted to calculate electron structure.It is proved that some regulations must be taken into ac- count in order to carry out alloy design calculation successfully,which are described in this paper in detail.

Multi-hazard performance assessment of a transfer-plate high-rise building

Many urban areas are located in regions of moderate seismicity and are subjected to strong wind. Buildings in these regions are often designed without seismic provisions. As a result, in the event of an earthquake, the potential for damage and loss of lives may not be known. In this paper, the performance of a typical high-rise building with a thick transfer plate （TP）, which is one type of building structure commonly found in Hong Kong, is assessed against both earthquake and wind hazards. Seismic- and wind-resistant performance objectives are first reviewed based on relevant codes and design guidelines for high-rise buildings. After a brief introduction of wind-resistant design of the building, various methodologies, including equivalent static load analysis （ESLA）, response spectrum analysis （RSA）, pushover analysis （POA）, linear and nonlinear time-history analysis （LTHA and NTHA）, are employed to assess the seismic performance of the building when subjected to frequent earthquakes, design based earthquakes and maximum credible earthquakes. The effects of design wind and seismic action with a common 50-year return period are also compared. The results indicate that most performance objectives can be satisfied by the building, but there are some objectives, such as inter-story drift ratio, that cannot be achieved when subjected to the frequent earthquakes. It is concluded that in addition to wind, seismic action may need to be explicitly considered in the design of buildings in regions of moderate seismicity.

A simplified methd of evaluating the seismic performance of buildings

This paper presents a simplified method of evaluating the seismic performance of buildings. The proposed method is based on the transformation of a multiple degree of freedom (MDOF) system to an equivalent single degree of freedom (SDOF) system using a simple and intuitive process. The proposed method is intended for evaluating the seismic performance of the buildings at the intermediate stages in design, while a rigorous method would be applied to the final design. The performance of the method is evaluated using a series of buildings which are assumed to be located in Victoria in western Canada, and designed based on the upcoming version of the National Building Code of Canada which is due to be published in 2005. To resist lateral loads, some of these buildings contain reinforced concrete moment resisting frames, while others contain reinforced concrete shear walls. Each building model has been subjected to a set of site-specific seismic spectrum compatible ground motion records, and the response has been determined using the proposed method and the general method for MDOF systems. The results from the study indicate that the proposed method can serve as a useful tool for evaluation of seismic performance of buildings, and carrying out performance based design.

Improved design of special boundary elements for T-shaped reinforced concrete walls

This study examines the design provisions of the Chinese GB 50011-2010 code for seismic design of buildings for the special boundary elements of T-shaped reinforced concrete walls and proposes an improved design method. Comparison of the design provisions of the GB 50011-2010 code and those of the American code ACI 318-14 indicates a possible deficiency in the T-shaped wall design provisions in GB 50011-2010. A case study of a typical T-shaped wall designed in accordance with GB 50011-2010 also indicates the insufficient extent of the boundary element at the non-flange end and overly conservative design of the flange end boundary element. Improved designs for special boundary elements ofT-shaped walls are developed using a displacement-based method. The proposed design formulas produce a longer boundary element at the non-flange end and a shorter boundary element at the flange end, relative to those of the GB 50011-2010 provisions. Extensive numerical analysis indicates that T-shaped walls designed using the proposed formulas develop inelastic drift of 0.01 for both cases of the flange in compression and in tension.

Probabilistic seismic loss estimation via endurance time method

Probabilistic Seismic Loss Estimation is a methodology used as a quantitative and explicit expression of the performance of buildings using terms that address the interests of both owners and insurance companies. Applying the ATC 58 approach for seismic loss assessment of buildings requires using Incremental Dynamic Analysis （IDA）, which needs hundreds of time-consuming analyses, which in turn hinders its wide application. The Endurance Time Method （ETM） is proposed herein as part of a demand propagation prediction procedure and is shown to be an economical alternative to IDA. Various scenarios were considered to achieve this purpose and their appropriateness has been evaluated using statistical methods. The most precise and efficient scenario was validated through comparison against IDA driven response predictions of 34 code conforming benchmark structures and was proven to be sufficiently precise while offering a great deal of efficiency. The loss values were estimated by replacing IDA with the proposed ETM-based procedure in the ATC 58 procedure and it was fotmd that these values suffer from varying inaccuracies, which were attributed to the discretized nature of damage and loss prediction functions provided by ATC 58.

基于现行规范的型钢混凝土柱侧力-位移曲线预测方法研究

型钢混凝土(steel reinforced concrete,SRC)柱因承载力高、刚度大和耐久性能好等优点而被广泛应用于高层结构中。然而,现阶段SRC结构设计普遍基于承载力设计法,基于性能的抗震设计法在SRC结构方面的应用仍待完善。作为基于性能(位移)的抗震设计方法中最重要的一环,现阶段SRC构件的侧力-位移关系评估缺乏规范指导。基于美国现行规范ASCE/SEI 41-17中针对钢筋混凝土构件的相关规定,结合SRC构件的受力与变形特征,提出了发生弯曲破坏的SRC柱在地震作用下的侧力-位移曲线建模方法。该曲线采用约束混凝土强度计算SRC构件的峰值承载力;使用刚度折减法考虑型钢与混凝土之间的黏结滑移;基于SRC构件的变形特征考虑了纵向受力钢材端部滑移对柱顶侧移的贡献。最后,通过与28根SRC柱试验结果的比较证明了曲线的适用性。计算结果表明:所提出的曲线能合理预测发生弯曲破坏的SRC柱的开裂荷载、开裂位移、峰值荷载、峰值位移和强度退化,可为SRC结构的性能化抗震设计提供参考。

考虑低周疲劳寿命的改进Park-Ang地震损伤模型

随着基于性态抗震设计理论的发展 ,Park Ang双参数地震损伤模型在建立性态目标量化准则方面受到重视。本文的研究目的是结合钢筋混凝土构件低周疲劳试验结果 ,对该模型作进一步发展和完善。基于低周反复荷载作用下钢筋混凝土构件疲劳寿命方程 ,结合国内外发表的试验结果分析了构件极限滞回耗能与位移延性系数的关系 ,近似为指数衰减关系。通过引入另外的与加载路径有关的能量项加权因子 βi,由定义的临界延性系数 μ0 和能量等效系数YE 计算 ,提出了Park Ang双参数地震损伤模型新的改进形式。改进的地震损伤模型规格化最大位移与规格化滞回耗能是非线性组合 ,可以近似考虑加载路径对损伤影响。试验和数值分析表明改进损伤模型可以有效地降低组合参数 β不确定性对损伤指数计算结果的影响 ,而新引入参数的不确定性对其计算结果几乎没有影响。分析了滞回耗能在构件地震累积损伤中所占的比重及其与加载路径的关系。建议了改进Park Ang双参数地震损伤模型可修复破坏和倒塌破坏损伤指数临界值可分别取为 0 4和 0 8。

考虑P-Δ效应的桥梁地震反应分析与设计

要实现基于性能的抗震设计理念,重要的一环为简单而准确地确定结构地震需求。P-Δ效应会使桥墩产生二阶内力和变形,在弹性状态下已有可靠的分析方法,但在地震作用下还没有得到充分的研究。本文在对地震作用下考虑P-Δ效应的现有分析和设计方法进行总结的基础上,进行了单墩体系地震作用下的动力P-Δ效应非线性时程统计分析,回归得到了P-Δ效应的位移增大系数和强度提高系数公式。研究表明,塑性反应的结构P-Δ效应与弹性反应阶段有很大差异,将弹性范围研究结果简单延伸到塑性阶段是不合适的。现有理论公式预测的位移增大系数和强度提高系数在工程上容许的P-Δ效应影响范围内均小于实际统计均值,精度不能满足基于性能抗震设计的要求。本文得到的回归公式与有限元分析结果较为吻合,可为基于性能的抗震设计提供参考。

基于改进Park-Ang模型的RC桥墩地震动损伤及滞回耗能特性研究

桥梁结构尤其是桥墩在强震作用下的地震动损伤、滞回耗能及其分布,是基于性能抗震设计的重要基础。本文引入改进的Park-Ang双参数损伤评估模型,以某靠近活动断层的高速公路RC梁式桥等效单墩模型为对象,深入分析了加速度峰值(PGA)、频谱、持时等三个地震动要素对损伤、滞回耗能及其分布的影响规律。研究表明,损伤及累积滞回耗能沿桥墩竖向自下而上显著减小,随着PGA的增大,墩底及附近截面的损伤指标明显增大,损伤高度不断扩大,损伤参与系数分布基本稳定,墩底损伤一般占桥墩总损伤的30%～40%。累积滞回耗能所致损伤可达总损伤的20%～80%,不容忽略。地震动频谱特性影响显著,当地震波卓越周期与结构自振周期接近时,会导致各项指标的显著增加。持时对损伤分布比例没有明显影响,但强震持时对于截面损伤值存在累加效应。

基于“投资-效益”准则的抗震性能目标优化决策

以结构在地震作用下的破坏程度为依据将结构性能水平划分为五级,并选取结构的层间位移角为定量控制指标,建立了"结构破坏程度结构性能水平层间位移角"之间的对应关系.该划分细化和量化了现行规范规定的三级性能水平,为设计人员和业主提供更多选择,使结构抗震设计更加灵活.同时以"投资效益"准则为基本原则,结合地震危险性分析,建立了改进的结构全寿命总费用模型.该模型不仅考虑了结构的初始造价,而且充分根据结构性能失效的特点考虑了结构在各级性能水平下的损失期望,全面注重了结构性能、安全及社会经济等因素,为实现基于性能的结构抗震设计提供了有效的理论依据和可靠的计算方法.

基于可靠度和功能的框架-剪力墙结构抗震优化设计

作为结构抗震设计的发展方向 ,近年来基于功能的结构抗震设计思想引起了地震工程界的广泛重视 ,并取得了迅速发展 ,其基本思想就是在充分考虑结构抗震设计中的不确定性的情况下 ,采用基于“投资—效益”准则和强调结构“个性”的设计。本文讨论了基于可靠度和功能的结构抗震优化设计思想 ,建立了钢筋混凝土框架 -剪力墙结构的抗震优化设计模型 ;给出了结构可靠度的近似计算方法 ,最后计算了钢筋混凝土框架 -剪力墙的算例。

钢框架-装配式混凝土抗侧力墙板结构基于性能的抗震设计方法

为研究钢框架-预制混凝土抗侧力墙板装配式结构体系(SPW体系)的基于性能的抗震设计方法,对4榀钢框架-预制混凝土抗侧力墙板结构足尺试件进行低周反复荷载作用下的试验研究。对SPW体系的抗震性能水平及性能指标的量化进行研究,提出5个性能水平的失效判别标准,并给出不同性能水平对应的层间位移角限值建议;提出SPW结构体系直接基于位移的抗震性能设计方法和设计步骤,并通过算例给出16层SPW结构体系的基于性能的抗震设计过程。实验结果表明:该结构体系为一种典型的双重抗侧力体系,加载过程呈现出明显的2个阶段性,抗侧力墙板为结构体系的第1道防线,钢框架为结构的第2道防线。

钢筋混凝土框架-剪力墙结构基于位移的抗震设计方法

根据钢筋混凝土框架-剪力墙结构的特点,将其性能划分为使用良好、保证人身安全和防止倒塌三个水平,并用层间位移角限值予以量化。以作用倒三角形水平分布荷载的等截面弯剪悬臂杆的侧移曲线作为其初始侧移模式。对于使用良好性能水平,将侧移曲线上反弯点对应的楼层处的层间位移角刚好达到相应限值时的侧移曲线作为目标侧移曲线,据此计算等效单自由度体系的等效参数以及原结构的基底剪力和各质点的水平地震作用。对于保证人身安全和防止倒塌的性能水平,根据Pushover曲线与需求曲线的关系对结构予以调整,使结构满足这两个性能水平的要求。

《钢结构与钢-混凝土组合结构设计方法》的理解与应用——钢结构抗震性能化设计

结构抗震设计的目标是小震不坏、中震可修、大震不倒,中震下结构进入弹塑性阶段,弹塑性阶段结构的地震力如何求得,是亟需解决的问题。根据《钢结构与钢-混凝土组合结构设计方法》,详细介绍了精细化延性抗震设计理论,影响结构性能系数R取值的各种因素,结构延性系数与构件宽厚比的关系。介绍了采用《钢结构设计标准》(GB 50017-2017)进行抗震性能化设计的流程,及性能系数最小值的确定依据。最后对我国《钢结构设计标准》(GB 50017-2017)在抗震性能化设计流程、性能系数的取值、构件宽厚比限值等方面提出了建议。

考虑桩-土相互作用效应的高速铁路桥梁桩基础抗震设计方法研究

针对强震下高速铁路桥梁桩基础抗震设计中存在的问题,对桩基础的抗震性能提出了多级设防目标并给出了相应的评价指标与合理取值.借鉴FEMA440考虑桩-土三种相互作用效应的能力谱法,采用p-y、t-z及q-z曲线模拟桩周土的柔性效应,用PMM铰模拟桩身的非线性,通过Pushover分析得到桥墩的能力曲线.引入FEMA440对地基运动学效应、地基阻尼效应的地震动需求谱修正算法,对需求谱进行了修正.探讨了应用性能点轨迹法求解桩基础的延性需求及性能点的过程.以高速铁路32 m简支箱梁桥墩为研究对象,通过实例验证了该法的可行性.