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1.
This study presents a seismic fragility analysis and ultimate spectral displacement assessment of regular low-rise masonry infilled (MI) reinforced concrete (RC) buildings using a coefficient-based method. The coefficient-based method does not require a complicated finite element analysis; instead, it is a simplified procedure for assessing the spectral acceleration and displacement of buildings subjected to earthquakes. A regression analysis was first performed to obtain the best-fitting equations for the inter-story drift ratio (IDR) and period shift factor of low-rise MI RC buildings in response to the peak ground acceleration of earthquakes using published results obtained from shaking table tests. Both spectral acceleration-and spectral displacement-based fragility curves under various damage states (in terms of IDR) were then constructed using the coefficient-based method. Finally, the spectral displacements of low-rise MI RC buildings at the ultimate (or near-collapse) state obtained from this paper and the literature were compared. The simulation results indicate that the fragility curves obtained from this study and other previous work correspond well. Furthermore, most of the spectral displacements of low-rise MI RC buildings at the ultimate state from the literature fall within the bounded spectral displacements predicted by the coefficient-based method. 相似文献
2.
Parametric earthquake response of torsionally coupled buildings with foundation interaction 总被引：2，自引：0，他引：2
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. 相似文献
3.
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. 相似文献
4.
双向偏心结构扭转耦联地震反应的序列最优控制 总被引：1，自引：0，他引：1
本文分析了不对称建筑结构平移-扭转耦联振动的动力特性及地震作用下的响应;根据地震动输入结构的过程,推导出一种更为一般的最优控制算法,所获得的控制力表达式同时包括地震响应和地震激励。通过对一非规则四层框架结构的扭转耦联地震反应控制分析表明,该算法不仅能有效地控制结构的平移地震反应,而且更有效地抑制结构的扭转耦联地震反应。 相似文献
5.
研究了具有不同自振特性的建筑结构在近断层速度脉冲型及非速度脉冲型地震动作用下的结构层间变形分布,揭示了近断层速度脉冲对工程结构地震响应的特殊影响. 从汶川MS8.0地震近断层强震记录中选取两组典型速度脉冲型记录和非脉冲型记录, 根据确定的目标地震动强度水平,利用时域叠加小波函数法对选择的强震记录进行调整, 使之与目标地震动水平对应的加速度反应谱保持一致, 以此作为结构地震反应分析的地震动输入. 选取具有不同自振特征的3层、11层和20层典型钢筋混凝土框架结构, 建立有限元分析模型, 分别计算在速度脉冲型与非速度脉冲型记录作用下这些结构层间变形分布. 研究表明,速度脉冲型记录与非速度脉冲型记录作用下结构层间变形有明显差异, 且与结构自振特征有关.就低层结构的层间变形而言, 非速度脉冲型记录的影响较速度脉冲型记录的影响大. 随着结构自振周期的增加, 高阶振型的影响更加明显. 与非速度脉冲型记录相比,速度脉冲型记录的结构层间位移反应中值及离散程度较大. 速度脉冲型记录更容易激发高层结构的高阶振型, 产生较大的层间位移反应. 非速度脉冲型记录对中低层结构层间变形影响较大.因此, 在开展近断层结构地震影响评价时, 应考虑近断层速度脉冲的影响. 相似文献
6.
This paper presents results of an analytical study of the inelastic earthquake torsional response of a class of setback frame buildings. In the first part of the study, the modal response spectrum analysis procedure is utilized to determine the yielding strengths of structural members in an idealized but representative setback frame building model. Results are then presented for the inelastic dynamic response of this setback building model subjected to an ensemble of six earthquake ground motions. The results indicate that the modal response spectrum analysis procedure is inadequate for preventing excessive response leading to concentration of damage in vulnerable structural members, such as those in the tower near the notch and those in the base (the part of the structure below the tower) near the perimeter at the opposite side of the tower. The second part of the study develops a modified equivalent static force procedure for strength design of such setback frame buildings. Response analyses show that the proposed procedure results in improved and satisfactory inelastic performance of the selected class of setback frame buildings, having a wide range of realistic configurations. 相似文献
7.
Mohammad Reza Falamarz-Sheikhabadi Mohsen Ghafory-Ashtiany 《Journal of Seismology》2012,16(4):815-827
The paper addresses the issue of researching into the engineering characteristics of rotational strong ground motion components and rotational effects in structural response. In this regard, at first, the acceleration response spectra of rotational components are estimated in terms of translational ones. Next, new methods in order to consider the effects of rotational components in seismic design codes are presented by determining the effective structural parameters in the rotational loading of structures due only to the earthquake rotational components. Numerical results show that according to the frequency content of rotational components, the contribution of the rocking components to the seismic excitation of short period structures can never be ignored. During strong earthquakes, these rotational motions may lead to the unexpected overturning or local structural damages for the low-rise multi-story buildings located on soft soil. The arrangement of lateral-load resisting system in the plan, period, and aspect ratio of the system can severely change the seismic loading of wide symmetric buildings under the earthquake torsional component. 相似文献
8.
以2021年5月21日云南漾濞6.4级地震所获取的漾濞台强震动记录作为输入,对不同高度(低层、多层和高层)钢筋混凝土框架结构以及一低层砖混结构进行动力时程分析,探讨不同高度钢筋混凝土框架结构动力响应特点,对比砖混结构与低层框架结构地震响应的不同,并对结构进行性能评定.主要分析结果表明,所有结构的楼层加速度响应中,竖向加速度放大效应显著,尤其是低层框架;框架结构Y方向楼层傅里叶幅值谱峰值主要在1~2.5 Hz频率范围;多层框架的层间位移角响应更大;所有框架结构以及设防的砖混结构层间位移角均未超过中等破坏限值;与低层框架结构相比,基本周期更短的砖混结构水平向楼层加速度放大效应更为显著;设防的砖混结构具有良好的抗震性能.分析结果可为灾区震害评估和震后修复提供指导,同时为建筑结构抗震设计提供一定参考. 相似文献
9.
Probabilistic fragility functions have been developed for low-rise, reinforced concrete buildings subjected to earthquake triggered slow-moving slides, applying a recently published methodology by the same authors [5] (Fotopoulou and Pitilakis, 2012). We performed an extensive numerical parametric study considering different idealized slope configurations, soil and geological settings, as well as distances of the structure to the slope's crest and foundation typologies. Various features of the structural damage are explored, highlighting trends on the building's behavior to the permanent co-seismic slope deformations. The proposed generalized probabilistic fragility curves have been developed as a function of the expected outcrop peak ground acceleration (PGA) as provided by modern seismic codes, i.e. EC8, or the induced permanent slope ground displacements (PGD) for different slope angles, water table level and soil type, foundation typology and seismic design code. Detailed sensitivity analyses of the above parameters, reveal their relative importance for the vulnerability analysis and the quantitative risk assessment of low-rise RC buildings subjected to earthquake triggered slow-moving slides. 相似文献
10.
传统低层建筑砌体结构动力特性分析中,易受到外界环境的干扰,砌体结构的完整性欠缺,导致动力特性分析的准确度较低。为提高低层建筑砌体结构的抗震性能,提出地震作用下低层建筑砌体结构的动力特性分析方法。首先利用低层建筑砌体结构反应自功率谱,完成砌体结构的自振频率辨认;然后通过941B型超低频率测振仪测试自振频率,筛出振动波形中噪声干扰的区域,获取时域波形和频域波形;最后依据时域波形和频域波形塑造低层建筑砌体三维精细化模型,在该模型基础上,通过子空间迭代算法获取低层建筑砌体结构的模拟结果,分析地震作用下芯柱、圈梁等构造措施对建筑砌体结构动力特征的影响,完成砌体结构的动力特性分析。实验结果表明,利用所提方法对地震作用下低层建筑砌体结构的动力特性进行分析,得到的分析结果准确度较高。 相似文献
11.
Four real buildings with three to six stories, strong irregularities in plan and little engineered earthquake resistance are subjected to inelastic response‐history analyses under 56 bidirectional EC8‐spectra‐compatible motions. The average chord rotation demand at each member end over the 56 response‐history analyses is compared to the chord rotation from elastic static analysis with inverted triangular lateral forces or modal response spectrum analysis. The storey‐average inelastic‐to‐elastic‐chord‐rotation‐ratio was found fairly constant in all stories, except when static elastic analysis is applied to buildings with large higher mode effects. Except for such buildings, static elastic analysis gives more uniform ratios of inelastic chord rotations to elastic ones within and among stories than modal response spectrum analysis, but generally lower than 1.0. With increasing EPA the building‐average inelastic‐to‐elastic‐chord‐rotation‐ratio decreases but scatter in the results increases. Static elastic analysis tends to overestimate the inelastic torsional effects at the flexible or central part of the torsionally flexible buildings and underestimate them at their stiff side. Modal response spectrum analysis tends to overestimate the inelastic torsional effects at the stiff or central part of the torsionally stiff buildings and underestimate them at the flexible side. Overall, for multistorey RC buildings that typically have fundamental periods in the velocity‐sensitive part of the spectrum, elastic modal response spectrum analysis with 5% damping gives on average unbiased and fairly accurate estimates of member inelastic chord rotations. If higher modes are not significant, elastic static analysis in general overestimates inelastic chord rotations of such buildings, even when torsional effects are present. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
The 2011 off the Pacific coast of Tohoku earthquake and response of high-rise buildings under long-period ground motions 总被引：1，自引：0，他引：1
I. Takewaki S. MurakamiK. Fujita S. YoshitomiM. Tsuji 《Soil Dynamics and Earthquake Engineering》2011
In the afternoon of March 11, 2011, the eastern Japan was severely attacked by the 2011 off the Pacific coast of Tohoku earthquake (the Great East Japan earthquake). Nearly 30,000 people were killed or are still missing by that earthquake and the ensuing monster tsunami as of April 11, 2011. This paper reports some aspects of this devastating earthquake which hit an advanced country in seismic resistant design. It has been reported that long-period ground motions were induced in Tokyo, Nagoya and Osaka. The properties of these long-period ground motions are discussed from the viewpoint of critical excitation and the seismic behavior of two steel buildings of 40 and 60 stories subjected to the long-period ground motion recorded at Shinjuku, Tokyo is determined and discussed. This paper also reports the effectiveness of visco-elastic dampers like high-hardness rubber dampers in the reduction of responses of super high-rise buildings subjected to such long-period ground motions. The response reduction rate is investigated in detail in addition to the maximum response reduction. In December 2010 before this earthquake, simulated long-period ground motions for earthquake resistant design of high-rise buildings were provided in three large cities in Japan (Tokyo, Nagoya and Osaka) and nine areas were classified. Two 40-story steel buildings (slightly flexible and stiff) are subjected to these long-period ground motions in those nine areas for the detailed investigation of response characteristics of super high-rise buildings in various areas. 相似文献
13.
This paper describes an analysis of damage costs to commercial and industrial property, including buildings (all low-rise), their contents, equipment and stock, in the Ms = 6.6 Edgecumbe New Zealand earthquake of 2 March 1987. The damage costs were converted to damage ratios by dividing by the value of the relevant property item. For the MM7 and MM9 intensity zones, the mean values and statistical distributions of these damage ratios were then found, the lognormal distribution fitting well. For all commercial and industrial buildings in the MM intensity IX zone (centroid MM9-4) the mean damage ratio was 0.076. The mean damage ratios were generally much smaller than estimated in previous studies. The buildings were all low-rise. There was no correlation between building and equipment damage ratios on a building by building basis. Considering dates of construction, it appears that mean damage levels at MM9 have not changed significantly for postcode buildings through changes in design standards up to the 1980s. 相似文献
14.
During a severe earthquake, steel moment resisting frames are expected to experience significant inelastic deformation in their members and joints. This behaviour is dependent upon several design parameters such as member sizes, frame's overstrength, member deformation capacities and the detailing of components. In this study, the influence of such aspects on the inelastic response of frames is investigated. Inelastic static and dynamic analyses were performed on four frames of different designs for a typical six-storey building. The frames were designed and detailed in accordance with current North American code requirements. The computed response of each frame was compared with the behaviour expected by the codes. Recommendations for a design procedure are suggested for improving the structural performance of low-rise steel frames subjected to strong earthquake excitation. 相似文献
15.
Analysis and comparison of the dynamic responses of three well instrumented (with accelerographs) high-rise buildings shaken during the 1984 Morgan Hill earthquake are presented. The buildings examined in the present work are (i) the Town Park Towers Apartment building, a 10-storey, concrete shear wall building; (ii) the Great Western Savings and Loan building, a 10-storey building with concrete frames and shear walls; and (iii) the Santa Clara County Office building, a 13-storey, moment-resistant steel frame building. The structures are located within 2 km of each other and, as may be confirmed by visual inspection of the recorded seismograms, experienced similar ground motions. One-dimensional and three-dimensional linear structural models are fitted to the observations using the modal minimization method' for structural identification, in order to determine optimal estimates of the parameters of the dominant modes of the buildings. The time-varying character of these parameters over the duration of the response is also investigated. Comparison of the recorded earthquake response of the structures reveals that the type of lateral-load-resisting system has an important effect on the dynamic behaviour of the structures because it controls the spacing of the characteristic modes on the frequency axis. The Santa Clara County Office building has closely spaced natural frequencies and exhibits strong torsional response and modal coupling. Its dynamic behaviour is contrasted with that of the Great Western Savings and Loan building which has well separated natural frequencies and exhibits small torsional response and no modal coupling. Strong modal coupling causes a beating-type phenomenon and makes earthquake response of structures different from that envisioned by codes. 相似文献
16.
W. K. Tso 《地震工程与结构动力学》1974,3(4):337-346
A study is made on the torsional-lateral motions of non-linear symmetrical structures subjected to lateral ground motion. The torsional and lateral response of a single mass symmetrical system subjected to sinusoidal ground motion is investigated. The load-displacement relationship of the resisting elements is taken to be weakly nonlinear of a softening type. It is shown that non-linear coupling exists between the lateral and rotational motions. For sinusoidal lateral response, the torsional motion equation can be cast in the form of a Mathieu equation. The likelihood of induced torsional response is then studied in terms of unstable regions in the parametric amplitude-frequency parameter space. The implication of this type of non-linear torsional-lateral coupling to the responses of real symmetrical structures subjected to actual earthquake ground motion is then discussed. 相似文献
17.
The collapse of the Olive View Hospital Psychiatric Day Clinic is studied using three biaxial force-deflection models to represent the columns of the building. These models are: shear collapse, elastic and inelastic. The biaxial models for shear and inelastic behaviour are new developments and are useful for non-linear structural dynamic studies. In the present study, the shear collapse model is intended to represent the actual prototype behaviour. The inelastic model, which is based on a hardening rule of plasticity, is used to study the performance of a hypothetical structure with the same storey shear capacity as the prototype but which exhibits ductile behaviour. The prototype structure had a base storey shear capacity of 25 per cent, and actually failed by shearing of all of the first floor columns. In the present study, the shear collapse model predicted this behaviour even with the El Centro accelerogram as input. This result may have far-reaching significance because many low-rise reinforced concrete buildings which were designed according to recent codes have similar storey shear capacity coefficients and column properties. According to this study, such buildings may collapse even in a moderate earthquake. In the inelastic representation, the structure was found to have a base storey shear capacity of 80 per cent when moment hinging was assumed to occur at the top and bottom of the columns. Even with this high strength capacity, the permanent offset computed from the inelastic model corresponded to a ductility factor of 5 when the Pacoima Dam accelerogram was used as input. On the basis of damage to other structures observed on the site, it seems likely that ground motion of about the Pacoima Dam intensity occurred at Olive View. From this it is concluded that a low-rise ductile frame concrete building, even with this high shear force capacity, may not prove satisfactory for hospital use when subjected to strong ground motion. 相似文献
18.
While much effort has been spent on analysis of individual structures, building class seismic damage estimators, of value in disaster planning, code-writing, city planning, national hazards policy formulation, etc., have been little investigated. Based largely on data from Sendai City, Japan in the 12 June, 1978 Miyagiken-oki earthquake (ML = 7.4), estimators of seismic damage for low- and mid-rise buildings in urban Japan have been determined. For low-rise buildings, based on damage to over 60,000 buildings, damage ratios for onset of damage and collapse and for cost of damage are found to correlate best with response spectra at 0.75 s. Using published test data and average building properties, a seismic damage model explains the low-rise building behaviour and permits examination of the effect of structural changes on the estimated damage. For mid-rise buildings, damage states (0: none, 4: total) are determined as a function of maximum storey displacement, based on published natural period determinations (pre- and post-earthquake) for 189 mid-rise buildings in Sendai. The effects of structural changes on expected damage can also be estimated. With these two building class damage estimators, a large part of future seismic damage to urban Japan can be estimated, as well as the effects of various mitigation measures. 相似文献
19.
This paper presents selected indicative results from an extensive parametric investigation that has been performed in order to assess the effects of potential earthquake‐induced poundings on the overall dynamic response of seismically isolated buildings. In particular, a seismically isolated building and its adjacent fixed‐supported buildings are subjected to various earthquake excitations that induce structural impact among the buildings in series. The results indicate that the seismically isolated building may hit against the adjacent buildings at the upper floor levels before the occurrence of any pounding at the isolation level with the surrounding moat wall. The severity of the impact depends on the dynamic properties of the adjacent buildings, in combination with the earthquake characteristics. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
20.
The work presented in this paper investigates the effect of the foundation flexibility on the coupled lateral-torsional response of single-storey buildings excited by translational ground motion. The eccentricity between the centre of mass and the centre of resistance is considered to be the only cause of coupling of the lateral and torsional response of the building. The study is confined to the steady-state response of rigidly supported and flexibly supported torsionally coupled buildings subjected to harmonic free-field ground displacement perpendicular to the direction of the eccentricity. In the case of the flexibly supported building the foundation medium is assumed to be an elastic homogeneous isotropic half-space. The effect of the controlling parameters on lateral-torsional coupling is investigated. It is concluded that for a particular range of values of these parameters (representing most cases of actual buildings) their effect on the coupling of lateral and torsional response is not qualitatively affected by increases in the flexibility of the foundation medium. 相似文献