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日本1995年阪神大地震及火山考察与启示 总被引：1，自引：0，他引：1
简述了１９９５年１月１７日日本７．２级阪神大地震的震害,地震断层以及１８９１年浓尾级地震根尾谷地震断裂、北伊豆地震旦那断层和大室火山、伊豆大岛火山的一些特征,最后论述了这次考察的启示。 相似文献
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为模拟钢框架结构的典型震害,本文基于ANSYS软件建立了钢框架结构简化模型。该模型可以考虑楼板对钢框架结构整体性能的影响,并且进一步考虑了楼板与钢梁之间的滑移、节点域变形,以及梁柱节点焊缝的断裂等因素。应用本文建立的钢框架结构模型对北岭地震中Blue Cross大厦的震害进行了模拟,与实际震害对比的结果表明,该模型能够比较精确地模拟地震作用下钢框架结构的响应。钢框架结构模型对节点焊缝断裂的钢框架结构震害研究有着重要的意义。 相似文献
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SRC-RC竖向混合结构过渡层抗震设计方法探讨 总被引：4，自引：0，他引：4
首先介绍了SRC-RC竖向混合结构的受力特点和性能优势;并针对我国和日本的相关规程及工程应用实践,结合日本阪神地震中SRC-RC竖向混合结构的主要震害特点,指出国内外SRC-RC竖向混合结构过渡层抗震设计方法所存在的主要问题及不足。在综合分析阪神地震后日本关于SRC-RC竖向混合结构过渡层抗震设计方法的最新研究进展的基础上,提出了SRC-RC竖向混合结构过渡层抗震设计的设计思路和方法,可为SRC-RC竖向混合结构过渡层抗震设计提供参考。 相似文献
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一、历史地震现场调查概况四川省会东县地处川滇交界附近的偏僻山区,1947年曾发生中强地震。1988年4月15日会东县鹿鹤乡发生5.2级地震,笔者随四川地震系统宏观考察组奔赴震区,除考察本次地震外,同时也注意搜集历史地震震害资料。由于历史地震发生的时间不太久远,当时的震害目击者多健在,许多震害情况为不同地点的群众所共同言及,增强了资料的可信度。为评定历史地震灾害程度,注意将同一地点的历史震害与本次地震震害进行对比,取得佐证。这次考察,对1947年6月7日会东地震及1893年禄劝地震增补了宏观震害资料,提出了校核会东地震震级参数 相似文献
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随着全球经济建设的快速发展,地下空间的利用已经成为学术界重要的研究课题。越来越多的震害表明,地下结构在强震作用下并不一定安全,甚至发生严重破坏。1985年墨西哥8.1级地震,1995年日本7.2级阪神地震以及2008年我国四川汶川8.0级地震都造成了大量的地下结构的损坏。研究地震作用下地下结构的稳定问题是当前岩土工程研究的热点课题之一,具有重要的理论和实际意义。地铁是现代城市的重要交通工具,是公众较为集中的地下空间,其安全稳定性受到了政府和社会的极大关注。本文以地铁地下结构为研究对象,对地下结构抗震研究的主要方法进行了系统的总结,对其中存在的问题及发展方向进行了讨论和评述;对三维有限差分程序FLAC3D的基本原理、功能及其在岩土工程抗震中的应用进行了详细的介绍;对地铁地下结构的抗震性能、震害机理以及实用抗震分析方法进行了深入的研究,主要成果如下: 相似文献
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日本阪神地震以后,日本政府吸取了阪神地震应急响应太慢的教训,投入巨资(约300亿美元)来加强日本的地震监测系统和地震信息系统。 相似文献
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1988年11月6日云南澜沧—耿马相继发生7.6级和7.2级地震。本文介绍这次地震损失较重的澜沧、耿马、沧源和双江四个县的民用建筑震害,初步分析了震害的原因,研究了各类房屋的震害特征,总结了从震害中应吸取的经验教训,为地震灾区重建家园和房屋抗震设计提供依据。 相似文献
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阪神大震灾后有关人士对日本首都圈震灾的估计日本首都圈会发生阪神大震灾规模的直下型地震吗？日本地震预报联络会和中央防灾会议认为：“南关东直下型地震极有可能在不久的将来发生”，因而在积极地充实地震预报体制和强化防实体制。但多数人认为，在连观测网还未充分的... 相似文献
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Rocking damage‐free steel column base with friction devices: design procedure and numerical evaluation 
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下载免费PDF全文 Earthquake‐resilient steel frames, such as self‐centering frames or frames with passive energy dissipation devices, have been extensively studied during the past decade, but little attention has been paid to their column bases. The paper presents a rocking damage‐free steel column base, which uses post‐tensioned high‐strength steel bars to control rocking behavior and friction devices to dissipate seismic energy. Contrary to conventional steel column bases, the rocking column base exhibits monotonic and cyclic moment–rotation behaviors that are easily described using simple analytical equations. Analytical equations are provided for different cases including structural limit states that involve yielding or loss of post‐tensioning in the post‐tensioned bars. A step‐by‐step design procedure is presented, which ensures damage‐free behavior, self‐centering capability, and adequate energy dissipation capacity for a predefined target rotation. A 3D nonlinear finite element (FE) model of the column base is developed in abaqus . The results of the FE simulations validate the accuracy of the moment–rotation analytical equations and demonstrate the efficiency of the design procedure. Moreover, a simplified model for the column base is developed in OpenSees . Comparisons among the OpenSees and abaqus models demonstrate the efficiency of the former and its adequacy to be used in nonlinear dynamic analysis. A prototype steel building is designed as a self‐centering moment‐resisting frame with conventional or rocking column bases. Nonlinear dynamic analyses show that the rocking column base fully protects the first story columns from yielding and eliminates the first story residual drift without any detrimental effect on peak interstory drifts. The study focuses on the 2D rocking motion and, thus, ignores 3D rocking effects such as biaxial bending deformations in the friction devices. The FE models, the analytical equations, and the design procedure will be updated and validated to cover 3D rocking motion effects after forthcoming experimental tests on the column base. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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传统抗弯钢框架的梁柱节点通常设计为刚性连接,这种刚性节点具有很大的抗弯刚度,然而节点延性不足,罕遇地震作用导致节点脆性断裂。研究学者提出了多种解决该问题的思路,例如半刚性连接节点、节点加强或削弱方法使塑性铰外移等。本文提出了一种简化的梁柱节点连接方式-铰接连接,改变梁柱节点的传力方式,在节点处设置隅撑提供框架的抗侧刚度,控制结构的失效模式。本文设计了三组抗弯钢框架和铰接隅撑钢框架,分别为3层、5层和8层结构,通过Pushover分析和非线性动力时程分析,对比二者之间的承载力、刚度、延性和层间侧移等抗震性能。研究结果表明:铰接隅撑钢框架具有和传统抗弯钢框架相似的抗侧刚度,且承载能力略高。罕遇地震作用下,铰接隅撑钢框架的层间侧移较小。传统抗弯钢框架失效模式为梁端出现塑性铰,而铰接隅撑钢框架的塑性区域转移至隅撑与梁连接部位。 相似文献
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Probabilistic demand and fragility assessment of welded column splices in steel moment frames 下载免费PDF全文
下载免费PDF全文 An assessment of seismic demands and capacities of welded column splice (WCS) connections in steel moment frames is presented. For demand assessment, nonlinear dynamic analyses are conducted for two case‐study buildings, that is, a 4‐story and a 20‐story moment frame. Results from the nonlinear dynamic analyses are assessed through a probabilistic seismic demand analysis (PSDA) framework to characterize recurrence rates of longitudinal flange stress in these connections. The PSDA is applied in two contexts. First, in the context of WCS connections constructed prior to the M 6.7 1994 Northridge earthquake, the PSDA is combined with sophisticated finite element‐based fracture mechanics analysis to compute the mean annual frequencies of fracture in these connections. The pre‐Northridge WCS are especially critical because they feature partial joint penetration and brittle materials that compromise their resistance to fracture. The analysis indicates that the mean annual frequencies of fracture in these connections may be unacceptably high for both the 4‐story and the 20‐story frames. This warrants a serious and urgent consideration of retrofit strategies. These findings are attributed to the brittleness of the pre‐Northridge splices (as indicated by the fracture mechanics simulations), as well as the force‐controlled nature of these components, wherein low‐intensity ground motions contribute disproportionately to fracture risk, as evidenced by fracture risk disaggregation. Second, in the context of new construction, the PSDA provides meaningful stress magnitudes for design. Currently, WCS connections employ complete joint penetration welds with the intent to develop the smaller column flange in yielding. The PSDA conducted in this study suggests that this requirement may be too stringent because stress demands in the splices corresponding even to high return periods (e.g., 2475 years) are significantly lower (~40 ksi), as compared with the stress required to yield the column (~55 ksi). Limitations of the study are outlined. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Ten full-scale steel beam-to-column moment connections used in moment-resisting frames （MRFs） were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one traditional welded flange-bolted web connection, one traditional fully welded connection, four beam flange strengthened connections, three beam flange weakened connections, and one through-diaphragm connection. The test results show that the connections with flange cover plates or with partly cut beam flanges satisfy the beam plastic rotation demand for ductile MRFs. From the measured stress profiles along the beam flange and beam web depth, the mechanics of brittle fracture at the end of the beam is discussed. Design recommendations for steel beam-to-column moment connections are proposed. 相似文献
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A refined probabilistic assessment of seismic demands and fracture capacity of welded column splice (WCS) connections in welded steel moment resisting frames (WSMRFs) is presented. Seismic demand assessment is performed through cloud-based nonlinear time history analysis (NLTHA) for two case-study structures, i.e., a 4- and a 20- story WSMRFs. Results from NLTHA are used to derive fracture fragility of WCS connections. To this aim, the study investigates (1) optimal ground-motion intensity measures for conditioning probabilistic seismic demand models in terms of global (i.e., maximum inter-story drift ratio) and local (i.e., peak tensile stress in the flange of WCSs) engineering demand parameters of WSMRFs; (2) the effect of ground-motion vertical components on the longitudinal flange stress of WCS connections and their resulting fracture fragility; and (3) the effect of WCS capacity uncertainties on the fracture fragility estimates of those connections. For the latter case, an advanced finite element fracture mechanics-based approach proposed by the authors is employed to capture aleatory and epistemic uncertainties affecting fracture capacities. The focus is on pre-Northridge WCS connections featuring partial joint penetration and brittle materials, making them highly vulnerable to seismic fracture. Fracture fragility results for the case-study structures are compared and discussed, highlighting the importance of the considered issues on fragility estimates, particularly in the case of high-rise structures. Findings from the study contribute shedding some light on the influence of seismic demand and capacity uncertainties on the assessment of fracture fragility of WCS connections. These findings can guide similar performance-based assessment exercises for WSMRFs to inform, for instance, the planning and design of retrofitting strategies for those vulnerable connections. 相似文献
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Studies are made on the structural damage at the Ashiyahama residential high‐rise steel building complex due to the Hyogo‐ken Nanbu Earthquake (Kobe Earthquake), which occurred on 17 January 1995. The axial breakage of very thick‐plated steel columns of the mega‐structure is unprecedented and has been attracting the special attention of structural engineers. The cause of the damage is first investigated from numerical computation with recourse to an explicit method of dynamic analysis based on a continuous medium. The numerical result is compared with that obtained from a conventional multi‐mass lumped stiffness model combined with an equivalent lateral‐force procedure. By comparing both the numerical results, the latter conventional method is shown to be inadequate for achieving earthquake‐resistant capability. The destructive power of the ground motion is found to have exceeded the horizontal earthquake‐resistant capacity that is prescribed in the structural design criteria. Great axial stresses are produced in columns by combined action of bending moment and axial force due to overturning moment. The fracture of heavy steel columns is caused from only the horizontal component of seismic ground motion. Actual locations of significant damage are closely related to the occurrence of plastic hinges in the analysis. It is emphasized as a warning to avoid yielding concentration in particular storeys. Lastly, recommendations to enhance earthquake‐resistant design are proposed from a practical point of view. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Decoupling algorithm for evaluating multiple beam damages in steel moment‐resisting frames 下载免费PDF全文
下载免费PDF全文 Post‐earthquake safety evaluation of steel moment‐resisting frames mainly relies on the inspection of seismic damage to beam–column connections. Recently, in order to evaluate seismic damage of steel connections in a prompt and precise manner, a local damage evaluation method based on dynamic strain responses has been proposed and receives attention. In the evaluation method where strain responses are measured by piezoelectric strain sensors, a strain‐based damage index has been developed for evaluating individual seismic beam damage in a steel frame. However, for a steel frame suffering multiple beam damages, the damage index deteriorates its performance in identifying small damages with the presence of neighboring severe damages because of the moment redistributions induced by larger damages. This paper presents a decoupling algorithm that removes the issue of damage interaction and improves the performance of the damage index. The decoupling algorithm was derived on the basis of damage‐induced moment release and redistribution mechanism. The effectiveness of the decoupling algorithm was numerically and experimentally investigated using a nine‐story steel frame model and a large scale five‐story steel frame testbed that can simulate multiple fractures at beam ends. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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This paper proposes a simple lattice model for collapse analysis of RC bridges subjected to earthquakes by using the extended distinct element method (EDEM). In the model, a concrete element consists of lumped masses connected to one another by springs, and a reinforcement bar is represented by a discrete model or an integrated model. The proposed lattice model is simple but its parameters are reasonably defined. It has fewer element nodes and connecting springs, which will be of benefit by shortening the CPU time. The processes to determine the initial stiffness of concrete and steel springs, the parameters of the constitutive model and the fracture criteria for springs are described. A re‐contact spring model is also proposed to simulate the re‐contact of the concrete after fracture of springs; and a general grid searching method is used to decrease the CPU time for judging re‐contact after fracture. The lattice model is assessed by numerical simulations and experiments. As an application, a damaged single‐column pier subjected to the Kobe Earthquake in 1995 is analysed by EDEM with the proposed model. The simulation results indicate that the proposed model predicts well qualitatively the collapse process of RC bridges. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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《地震工程与结构动力学》2018,47(6):1460-1477
This paper presents the development, experimental testing, and numerical modelling of a new hybrid timber‐steel moment‐resisting connection that is designed to improve the seismic performance of mid‐rise heavy timber moment‐resisting frames (MRF). The connection detail incorporates specially designed replaceable steel links fastened to timber beams and columns using self‐tapping screws. Performance of the connection is verified through experimental testing of four 2/3 scale beam‐column connections. All 4 connection specimens met the acceptance criteria specified in the AISC 341‐10 provisions for steel moment frames and exhibit high strength, ductility, and energy dissipation capacity up to storey drifts exceeding 4%. All of the timber members and self‐tapping screw connections achieved their design objective, remaining entirely elastic throughout all tests and avoiding brittle modes of failure. To assess the global seismic performance of the newly developed connection in a mid‐rise building, a hybrid timber‐steel building using the proposed moment‐resisting connection is designed and modelled in OpenSees. To compare the seismic performance of the hybrid MRF with a conventional steel MRF, a prototype steel‐only building is also designed and modelled in OpenSees. The building models are subject to a suite of ground motions at design basis earthquake and maximum credible earthquake hazard levels using non‐linear time history analysis. Analytical results show that drifts and accelerations of the hybrid building are similar to a conventional steel building while the foundation forces are significantly reduced for the hybrid structure because of its lower seismic weight. The results of the experimental program and numerical analysis demonstrate the seismic performance of the proposed connection and the ability of the hybrid building to achieve comparable seismic performance to a conventional steel MRF. 相似文献