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1.
Chia-Ming Uang 《地震工程与结构动力学》1991,20(4):389-397
This paper compares the seismic force reduction factors used in the United States and Japan. Since these factors appear in a very different format in the two countries, for comparison purposes, a general expression relating the force reduction factor to the structural ductility and overstrength factors is first established. This study shows that (i) the seismic design limit state philosophy applied to moderate and severe earthquakes is treated differently in each country; (ii) the Japanese code requires the designer to check explicitly the serviceability limit state, while the American codes do not require the member's strength be checked for the serviceability limit state; (iii) the force reduction factors used in Japan for the ultimate limit state check are significantly smaller than those used in the United States, and (iv) the force reduction factors used in Japan are even smaller if structural overstrength is not explicitly checked by designers. 相似文献
2.
Hemchandra Chaulagain Hugo Rodrigues Enrico Spacone Ramesh Guragain Radhakrishna Mallik Humberto Varum 《地震工程与工程振动(英文版)》2014,13(3):455-470
Most current seismic design includes the nonlinear response of a structure through a response reduction factor(R). This allows the designer to use a linear elastic force-based approach while accounting for nonlinear behavior and deformation limits. In fact, the response reduction factor is used in modern seismic codes to scale down the elastic response of a structure. This study focuses on estimating the actual ‘R' value for engineered design/construction of reinforced concrete(RC) buildings in Kathmandu valley. The ductility and overstrength of representative RC buildings in Kathmandu are investigated. Nonlinear pushover analysis was performed on structural models in order to evaluate the seismic performance of buildings. Twelve representative engineered irregular buildings with a variety of characteristics located in the Kathmandu valley were selected and studied. Furthermore, the effects of overstrength on the ductility factor, beam column capacity ratio on the building ductility, and load path on the response reduction factor, are examined. Finally, the results are further analyzed and compared with different structural parameters of the buildings. 相似文献
3.
Performance-based seismic design of nonstructural building components:The next frontier of earthquake engineering 总被引：1，自引：1，他引：0
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. 相似文献
4.
A parametric study of 13 608 ductile moment‐resisting steel frames designed according to Eurocodes 3 and 8 is performed. A flowchart for the evaluation of the seismic‐resistant capacity of the designed frames is developed based on the N2 method. The design structural overstrength, ductility supply, plastic redistribution parameter, supply reduction factor and performance ratio of the frames are analysed. We determine that the frames have performance ratios higher than 1, mostly due to high values of design structural overstrength, showing that the seismic supply produced by the restraints of Eurocodes 3 and 8 is always higher than the seismic demand. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
5.
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. 相似文献
6.
In recent years, several research groups have studied a new generation of analysis methods for seismic response assessment of existing buildings. Nevertheless, many important developments are still needed in order to define more reliable and effective assessment procedures. Moreover, regarding existing buildings, it should be highlighted that due to the low knowledge level, the linear elastic analysis is the only analysis method allowed. The same codes (such as NTC2008, EC8) consider the linear dynamic analysis with behavior factor as the reference method for the evaluation of seismic demand. This type of analysis is based on a linear-elastic structural model subject to a design spectrum, obtained by reducing the elastic spectrum through a behavior factor. The behavior factor (reduction factor or q factor in some codes) is used to reduce the elastic spectrum ordinate or the forces obtained from a linear analysis in order to take into account the non-linear structural capacities. The behavior factors should be defined based on several parameters that influence the seismic nonlinear capacity, such as mechanical materials characteristics, structural system, irregularity and design procedures. In practical applications, there is still an evident lack of detailed rules and accurate behavior factor values adequate for existing buildings. In this work, some investigations of the seismic capacity of the main existing RC-MRF building types have been carried out. In order to make a correct evaluation of the seismic force demand, actual behavior factor values coherent with force based seismic safety assessment procedure have been proposed and compared with the values reported in the Italian seismic code, NTC08. 相似文献
7.
Performance-Based Seismic Design is now widely recognized as the pre-eminent seismic design and assessment methodology for
building structures. In recognition of this, seismic codes may require that buildings achieve multiple performance objectives
such as withstanding moderate, yet frequently occurring earthquakes with minimal structural and non-structural damage, while
withstanding severe, but rare earthquakes without collapse and loss of life. These objectives are presumed to be satisfied
by some codes if the force-based design procedures are followed. This paper investigates the efficacy of the Eurocode 8 force-based
design provisions with respect to RC frame building design and expected seismic performance. Four, eight, and 16-storey moment
frame buildings were designed and analyzed using the code modal response spectrum analysis provisions. Non-linear time-history
analyses were subsequently performed to determine the simulated seismic response of the structures and to validate the Eurocode
8 force-based designs. The results indicate the design of flexural members in medium-to-long period structures is not significantly
influenced by the choice of effective member stiffness; however, calculated interstorey drift demands are significantly affected.
This finding was primarily attributed to the code’s enforcement of a minimum spectral ordinate on the design spectrum. Furthermore,
design storey forces and interstorey drift demand estimates (and therefore damage), obtained by application of the code force-based
design procedure varied substantially from those found through non-linear time-history analysis. Overall, the results suggest
that though the Eurocode 8 may yield life-safe designs, the seismic performance of frame buildings of the same type and ductility
class can be highly non-uniform. 相似文献
8.
Incremental dynamic analysis and nonlinear static pushover analysis are carried out on a performance-based design to determine the seismic demands and capacities of an elliptic braced moment resisting frame (ELBRF). The objective is to assess ductility, overstrength and response modification factors in a modern steel-braced structural system based on incremental dynamic analysis. This integrated system is connected to a beam and column with an appropriate length while providing enough architectural space to allow for an opening without having the common problems associated with architectural spaces in braced systems. Several different classes of buildings are considered on soil type II. Linear dynamic analysis, nonlinear static pushover analysis and incremental nonlinear dynamic analysis related to 12 records from past earthquakes are carried out using OpenSees software. The factors of ductility, overstrength and response modification are calculated for this system. The values of 9.5 and 6.5 are found and suggested only for the response modification factor for ELBRF systems in allowable stress and ultimate limit state methods, respectively. The fragility curves are plotted for the first time for this type of bracing, which contributes to the assessment of building seismic damage. 相似文献
9.
Displacement capacity of masonry buildings as a basis for the assessment of behavior factor: an experimental study 总被引：3，自引：2，他引：1
The results of shaking table tests of a series of 1:5 scale masonry building models have been used for the assessment of values
of structural behavior factor q for masonry structures, seismic force reduction factors proposed for the calculation of design seismic loads by Eurocode
8, European standard for the design of structures for earthquake resistance. Six models have been tested, representing prototype
buildings of two different structural configurations and built with two different types of masonry materials. The study indicated
that the reduction of seismic forces for the design depends not only on the type of masonry construction system, but also
on structural configuration and mechanical characteristics of masonry materials. It has been also shown that besides displacement
and energy dissipation capacity, damage limitation requirement should be taken into account when evaluating the values of
behavior factor. On the basis of analysis of experimental results a conclusion can be made, that the values at the upper limit
of the proposed range of values of structural behavior factor q for unreinforced and confined masonry construction systems are adequate, if pushover methods are used and the calculated
global ductility of the structure is compared with the displacement demand. In the case where elastic analysis methods are
used and significant overstrength is expected, the proposed values are conservative. However, additional research and parametric
studies are needed to propose the modifications. 相似文献
10.
徐幼麟 《地震工程与工程振动(英文版)》2007,6(4):371-382
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 fi rst 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 satisfi ed 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. 相似文献
11.
Zhi Zhang Robert B. Fleischman Jose I. Restrepo Gabriele Guerrini Arpit Nema Dichuan Zhang Ulina Shakya Georgios Tsampras Richard Sause 《地震工程与结构动力学》2018,47(10):1987-2011
A new floor connecting system developed for low‐damage seismic‐resistant building structures is described herein. The system, termed Inertial Force‐Limiting Floor Anchorage System (IFAS), is intended to limit the lateral forces in buildings during an earthquake. This objective is accomplished by providing limited‐strength deformable connections between the floor system and the primary elements of the lateral force‐resisting system. The connections transform the seismic demands from inertial forces into relative displacements between the floors and lateral force‐resisting system. This paper presents the IFAS performance in a shake‐table testing program that provides a direct comparison with an equivalent conventional rigidly anchored‐floor structure. The test structure is a half‐scale, 4‐story reinforced concrete flat‐plate shear wall structure. Precast hybrid rocking walls and special precast columns were used for test repeatability in a 22‐input strong ground‐motion sequence. The structure was purposely designed with an eccentric wall layout to examine the performance of the system in coupled translational‐torsional response. The test results indicated a seismic demand reduction in the lateral force‐resisting system of the IFAS structure relative to the conventional structure, including reduced shear wall base rotation, shear wall and column inter‐story drift, and, in some cases, floor accelerations. These results indicate the potential for the IFAS to minimize damage to the primary structural and non‐structural components during earthquakes. 相似文献
12.
Nonstructural components(NSCs)are parts,elements,and subsystems that are not part of the primary loadbearing system of building structures but are subject to seismic loading.Damage to NSCs may disrupt the functionality of buildings and result in significant economic losses,injuries,and casualties.In past decades,extensive studies have been conducted on the seismic performance and seismic design methods of NSCs.As the input for the seismic design of NSCs,floor response spectra(FRS)have attracted the attention of researchers worldwide.This paper presents a state-of-the-art review of FRS.Different methods for generating FRS are summarized and compared with those in current seismic design codes.A detailed review of the parameters influencing the FRS is presented.These parameters include the characteristics of ground motion excitation,supporting building and NSCs.The floor acceleration response and the FRS obtained from experimental studies and field observations during earthquakes are also discussed.Three RC frames are used in a case study to compare the peak floor acceleration(PFA)and FRS calculated from time history analyses(THA)with that generated using current seismic design codes and different methods in the literature.Major knowledge gaps are identified,including uncertainties associated with developing FRS,FRS generation methods for different types of buildings,the need for comprehensive studies on absolute acceleration,relative velocity,and relative displacement FRS,and the calibration of FRS by field observations during earthquakes. 相似文献
13.
Gennaro Magliulo Vittorio Capozzi Roberto Ramasco 《Bulletin of Earthquake Engineering》2012,10(2):679-694
The paper presents the results of a research study concerning the seismic response and design of r/c frames with overstrength
discontinuities in elevation. The discontinuities are obtained assigning overstrengths either to the beams or to the columns
of a “regular frame” (assumed as reference). Two “regular frames” are designed: one according to the Eurocode 8 (EC8) medium
ductility class (DCM) rules and the other one according to the EC8 high ductility class (DCH) rules. For all frames the criteria
of vertical strength irregularity of many international seismic codes are applied. Non linear static and dynamic analyses
are performed; mechanical non linearity is concentrated at the element ends. These analyses are carried out according to EC8
provisions: for non linear static analysis the N2 method is applied; in the case of non linear time-history analyses, seven
real earthquakes, selected in order to fit on average the elastic design spectrum, are used as input. The seismic response
of frames characterised by the assigned overstrength is not very different with respect to the “regular frame” one; furthermore
all the frames satisfy the Ultimate Limit State, verified by the application of non linear static and dynamic analyses. This
demonstrates that the sensitivity of frames, designed according to EC8 medium and high ductility classes, to overstrength
vertical variations is low. Consequently, international code provisions on vertical strength regularity should be reviewed. 相似文献
14.
15.
Establishment of performance‐based seismic design factors for precast concrete floor diaphragms 
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下载免费PDF全文 This paper presents an analytical study used to establish design factors for a new seismic design methodology for precast concrete floor diaphragms. The design factors include diaphragm force amplification factors Ψ and diaphragm shear overstrength factors Ωv. The Ψ factors are applied to the ASCE7‐05 diaphragm design forces to produce diaphragm design strengths aligned to different performance targets. These performance targets are based on diaphragm detailing choices, and include: (i) elastic diaphragm behavior or (ii) limiting inelastic deformation demand on the diaphragm reinforcement (connectors between precast units or reinforcing bars in a topping slab) to within their reliable deformation capacities. The Ωv factors provide overstrength relative to the diaphragm bending strength for capacity protection against shear failure. The analytical study was performed by conducting nonlinear time history analyses of a simple evaluation structure, of which the dimensions and structural properties were varied. The analytical model used in the study is constructed and calibrated on the basis of extensive physical testing. The analytically obtained values of the diaphragm design factors are presented as functions of the geometric and structural properties of the building. The design factors presented here have been verified through evaluation of a set of realistic precast prototype structures. The diaphragm design methodology is currently in the codification process. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
目前我国房屋建筑抗震采用的以小震弹性计算为基础的设计方法,使工程师忽视了对建筑结构在强烈地震作用下破坏模式的充分考虑与设计,使得建筑结构的大震安全性有时难以得到保证。＂破坏-安全＂抗震理念,以房屋建筑最重要的抗震安全性能为目标,要求设计人员对结构的预期破坏模式有充分的把握和控制,使结构在强烈地震作用下能够形成明确的预期破坏模式并具备一定的耗能能力,从而以经济的代价保证结构其余部分在强烈地震作用下的安全。本文结合我国汶川地震灾后恢复重建与加固改造的实际情况,介绍了＂破坏-安全＂抗震理念及其设计概念,并介绍了国内外研究人员与工程师在实现＂破坏-安全＂抗震理念方面所提出的创新抗震结构体系及其研究成果。希望＂破坏-安全＂这一抗震理念及其相关技术能够在我国广大的经济欠发达地区的抗震设计实践中得到推广,以全面提高我国经济欠发达地区房屋建筑的抗震安全性。 相似文献
17.
剪切型结构的抗震强度折减系数研究 总被引：1，自引：0，他引：1
为了研究剪切型结构抗震强度需求的变化规律,本文基于单自由度体系的非线性时程分析,研究了不同场地条件下延性折减系数与位移延性系数和结构自振周期的关系;采用修正等效单自由度体系位移延性折减系数的方法,研究了剪切型多自由度体系的延性折减系数;以基于中国建筑抗震规范设计的代表不同抗震能力要求的RC框架结构为分析对象,通过静力弹塑性分析,研究了RC框架结构的体系超强能力。分析结果表明场地类别、位移延性水准和结构振动周期对单自由度体系的延性折减系数有显著的影响;多自由度体系的抗震延性折减系数明显比其相应的等效单自由度体系的抗震延性折减系数小;RC框架结构的超强系数一般随结构楼层数的增加而减小,随抗震设防烈度的增大而减小,内框架的超强系数比边框架的超强系数大。 相似文献
18.
This paper summarizes the results of an extensive study on the inelastic seismic response of X‐braced steel buildings. More than 100 regular multi‐storey tension‐compression X‐braced steel frames are subjected to an ensemble of 30 ordinary (i.e. without near fault effects) ground motions. The records are scaled to different intensities in order to drive the structures to different levels of inelastic deformation. The statistical analysis of the created response databank indicates that the number of stories, period of vibration, brace slenderness ratio and column stiffness strongly influence the amplitude and heightwise distribution of inelastic deformation. Nonlinear regression analysis is employed in order to derive simple formulae which reflect the aforementioned influences and offer a direct estimation of drift and ductility demands. The uncertainty of this estimation due to the record‐to‐record variability is discussed in detail. More specifically, given the strength (or behaviour) reduction factor, the proposed formulae provide reliable estimates of the maximum roof displacement, the maximum interstorey drift ratio and the maximum cyclic ductility of the diagonals along the height of the structure. The strength reduction factor refers to the point of the first buckling of the diagonals in the building and thus, pushover analysis and estimation of the overstrength factor are not required. This design‐oriented feature enables both the rapid seismic assessment of existing structures and the direct deformation‐controlled seismic design of new ones. A comparison of the proposed method with the procedures adopted in current seismic design codes reveals the accuracy and efficiency of the former. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
19.
The estimation of cyclic deformation demand resulting from earthquake loads is crucial to the core objective of performance‐based design if the damage and residual capacity of the system following a seismic event needs to be evaluated. A simplified procedure to develop the cyclic demand spectrum for use in preliminary seismic evaluation and design is proposed in this paper. The methodology is based on estimating the number of equivalent cycles at a specified ductility. The cyclic demand spectrum is then determined using well‐established relationships between seismic input energy and dissipated hysteretic energy. An interesting feature of the proposed procedure is the incorporation of a design spectrum into the proposed procedure. It is demonstrated that the force–deformation characteristics of the system, the ductility‐based force‐reduction factor Rμ, and the ground motion characteristics play a significant role in the cyclic demand imposed on a structure during severe earthquakes. Current design philosophy which is primarily based on peak response amplitude considers cyclic degradation only in an implicit manner through detailing requirements based on observed experimental testing. Findings from this study indicate that cumulative effects are important for certain structures, classified in this study by the initial fundamental period, and should be incorporated into the design process. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
20.
振戎中学食堂楼耗能减震分析与设计(Ⅱ)－能力谱法与地震损伤性能控制设计 总被引：1，自引：0，他引：1
本文针对云南洱源县振戎中学食堂钢筋混凝土耗能减振体系，首先建立了耗能减振结构构件的恢复力模型；其次，结合文献[10]提出的“三水准”地震损伤性能目标和文献[11]中的简化设计方法以及ATC-40报告中的能力谱法，对此结构在大震下的地震损伤性能进行了分析和设计验算；最后考察了耗能减振装置对结构损伤性能的控制效果。 相似文献