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251.
Seismic performance of an unreinforced masonry building: An experimental investigation 总被引:1,自引:0,他引:1
This paper presents the results of an experimental investigation carried out to investigate the seismic performance of a two storey brick masonry house with one room in each floor. A half‐scale building constructed using single wythe clay brick masonry laid in cement sand mortar and a conventional timber floor and timber roof clad with clay tiles was tested under earthquake ground motions on a shaking table, first in the longitudinal direction and then in the transverse direction. In each direction, the building was subjected to different ground motions with gradually increasing intensity. Dynamic properties of the system were assessed through white‐noise tests after each ground motion. The building suffered increasing levels of damage as the excitations became more severe. The damage ranged from cracking to global/local rocking of different piers and partial out‐of‐plane failure of the walls. Nevertheless, the building did not collapse under base excitations with peak ground acceleration up to 0.8g. General behaviour of the tested building model during the tests is discussed, and fragility curves are developed for unreinforced masonry buildings based on the experimental results. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
252.
This paper presents an innovative set of high‐seismic‐resistant structural systems termed Advanced Flag‐Shaped (AFS) systems, where self‐centering elements are used with combinations of various alternative energy dissipation elements (hysteretic, viscous or visco‐elasto‐plastic) in series and/or in parallel. AFS systems is developed using the rationale of combining velocity‐dependent with displacement‐dependent energy dissipation for self‐centering systems, particularly to counteract near‐fault earthquakes. Non‐linear time‐history analyses (NLTHA) on a set of four single‐degree‐of‐freedom (SDOF) systems under a suite of 20 far‐field and 20 near‐fault ground motions are used to compare the seismic performance of AFS systems with the conventional systems. It is shown that AFS systems with a combination in parallel of hysteretic and viscous energy dissipations achieved greater performance in terms of the three performance indices. Furthermore, the use of friction slip in series of viscous energy dissipation is shown to limit the peak response acceleration and induced base‐shear. An extensive parametric analysis is carried out to investigate the influence of two design parameters, λ1 and λ2 on the response of SDOF AFS systems with initial periods ranging from 0.2 to 3.0 s and with various strength levels when subjected to far‐field and near‐fault earthquakes. For the design of self‐centering systems with combined hysteretic and viscous energy dissipation (AFS) systems, λ1 is recommended to be in the range of 0.8–1.6 while λ2 to be between 0.25 and 0.75 to ensure sufficient self‐centering and energy dissipation capacities, respectively. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
253.
近年来,目标管理理论越来越多地应用于各级政府的绩效考核,目标管理考核,通过对各项业务工作实行目标分解,采取定性与定量相结合的分析方法,对各项工作目标实行量化,年终按所定目标进行考核,客观公正地评价单位和个人的业绩,增强工作的计划性和预见性,以充分调动干部职工的积极性。 相似文献
254.
255.
总结了2008年汶川8.0级地震在甘肃陇南地区造成的农村房屋和城镇房屋的典型震害及其原因。考察发现,由于农村房屋一般未经抗震设防设计,在本次地震中即使在低烈度地区仍然震害严重;而城镇房屋震害较轻,一般均表现出良好的抗震性能,严重破坏的大多是一些施工质量差,缺乏良好的抗震概念设计以及改建时未考虑抗震设计的建筑。建筑震害调查的几个地区设防烈度均为Ⅷ度,实际烈度为Ⅵ~Ⅸ度,因此这些地区的房屋震害情况刚好能反映这些地区房屋抵抗小震、中震及大震的能力。结果表明,严格按照抗震规范设计、并保证施工质量的建筑基本都能达到三水准设防目标。最后本文对灾后重建和抗震设防提出了建议。 相似文献
256.
L形截面短肢剪力墙抗震性能的模型试验研究 总被引:2,自引:0,他引:2
为了研究L形截面短肢剪力墙的抗震性能,对6个1/2缩尺比例的L形截面短肢剪力墙试件进行了低周反复荷载作用下的试验研究,分析了轴压比、截面高厚比、剪跨比等参数变化时,对试件的承载力、延性、滞回特性、耗能能力及破坏特性等抗震性能的影响。结果表明:L形截面短肢剪力墙试件扭转变形较小,试件以弯剪破坏为主,腹板底部为试件最薄弱部位,剪跨比小,轴压比大的试件腹板中心剪切破坏现象明显;试件随着截面高厚比、轴压比的提高,极限承载力增加,试件耗能能力变差、延性下降明显;L形截面短肢剪力墙试件在截面高厚比适中,为6.5∶1时,经济、抗震性能也较好。 相似文献
257.
Steel-concrete composite structures that share the advantages of both steel structure and concrete structure have been developed rapidly and used widely. It has been a popular structure in high-rise buildings in recent years. Although more and more composite structures have been used in earthquake area, only a few literatures about fragility analysis of this type of structure are available. In this paper, a fragility analysis method based on performance is proposed, in which both the uncertainty due to vari... 相似文献
258.
Seismic hazard disaggregation in performance‐based earthquake engineering: occurrence or exceedance?
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Seismic hazard disaggregation is commonly used as an aid in ground‐motion selection for the seismic response analysis of structures. This short communication investigates two different approaches to disaggregation related to the exceedance and occurrence of a particular intensity. The impact the different approaches might have on a subsequent structural analysis at a given intensity is explored through the calculation of conditional spectra. It is found that the exceedance approach results in conditional spectra that will be conservative when used as targets for ground‐motion selection. It is however argued that the use of the occurrence disaggregation is more consistent with the objectives of seismic response analyses in the context of performance‐based earthquake engineering. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
259.
Evaluation of the exact conditional spectrum and generalized conditional intensity measure methods for ground motion selection
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Two existing, contemporary ground motion selection and modification procedures – (i) exact conditional spectrum (CS‐exact) and (ii) generalized conditional intensity measure (GCIM) – are evaluated in their ability to accurately estimate seismic demand hazard curves (SDHCs) of a given structure at a specified site. The amount of effort involved in implementing these procedures to compute a single SDHC is studied, and a case study is chosen where rigorous benchmark SDHCs can be determined for evaluation purposes. By comparing estimates from ground motion selection and modification procedures with the benchmark, we conclude that estimates from CS‐exact are unbiased in many of the cases considered. The estimates from GCIM are even more accurate, as they are unbiased for most – but not all – of the cases where estimates from CS‐exact are biased. We find that it is possible to obtain biased SDHCs from GCIM, even after employing a very diverse collection of intensity measures to select ground motions and implementing its bias‐checking feature, because it is usually difficult to identify intensity measures that are truly ‘sufficient’ for the response of a complex, multi‐degree‐of‐freedom system. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
260.
The study aims at investigating the structural behavior of the Fatih Sultan Mehmet Suspension Bridge, i.e. the second Bosphorus Bridge in Turkey, under multi-point earthquake excitations, and determining the earthquake performance of the bridge based on the results obtained from this analysis. For this objective, spatially varying ground motions in triple direction were produced for each support of the bridge considering the Mw=7.4 scenario earthquakes on the main Marmara Fault. In order to simulate the ground motions, modified stochastic finite-fault technique was utilized. Taking the ground motions into account, non-linear time-history analysis was carried out, and the results obtained from the analysis were compared to those from uniform support earthquake excitation to identify the effects of multi-point earthquake excitations on the seismic performance of the bridge. From the analysis, it was determined that modal response of the towers and the deck was mostly effective on dynamic response of the entire bridge rather than other structural elements, such as cable and approach viaduct. Compared to the results obtained from simple-point earthquake excitation, noticeable axial force increase in the cable elements was obtained under multi-point earthquake excitation. The changes at the main cable and the side span cable were determined as 21% and 18%, respectively. This much increase in the cable elements led to increase in axial force at the towers and in shear force at the base section of the tower column. These changes in the structural elements were closely related to response of the deck and the towers since they had considerable contribution to response of the entire bridge. Based on the findings from the study, spatially varying ground motions has to be considered for long span suspension bridges, and the multi-support earthquake analysis should be carried out for better understanding and obtaining reliable results necessary for retrofitting and performance evaluation. 相似文献