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1.
桥梁高墩位移延性能力的探讨   总被引:3,自引:3,他引:12  
本文运用增量动力分析方法来计算高墩的屈服位移、极限位移和位移延性,给出了应用IDA方法计算屈服位移、极限位移的主要过程,探讨了高阶振型对高墩位移延性能力的影响。通过算例分析表明:现行计算桥墩位移延性系数的方法,如直接应用到高墩,将会导致较大误差;高阶振型对高墩的屈服位移、极限位移和位移延性系数都有较大的影响。  相似文献
2.
基于单地震动记录IDA方法的结构倒塌分析   总被引:2,自引:2,他引:3  
增量动力分析(Incremental Dynamic Analysis, IDA)作为静力Pushover分析的动力拓展,可以全面、准确地分析结构的性能变化,尤其可以很好地分析结构倒塌这一动力失稳问题.本文基于单地震动记录的IDA方法,提出了"折半取中"原则,以确定结构倒塌极限状态点.以一榀五层三跨钢筋混凝土框架结构为例,分别考虑钢筋强化模型、理想弹塑性模型和软化模型,对其进行倒塌分析.结果表明:钢筋的屈服后强化特性对结构抗倒塌能力具有显著的影响.  相似文献
3.
结构影响系数是基于强度的抗震设计中确定设计地震作用的关键,也是基于性态抗震设计理论的基础。位移放大系数则是根据结构的弹性位移估算弹塑性位移的关键参数。本文采用增量动力分析方法求解结构影响系数和位移放大系数,并结合具体算例详细说明了基于增量动力分析求解结构影响系数和位移放大系数的实施步骤。该方法能反映结构的动力特征,并能考虑高阶振型对结构抗震性能的影响。  相似文献
4.
高墩大跨连续刚构桥梁地震易损性分析   总被引:1,自引:1,他引:2  
基于增量动力分析方法,通过非线性地震反应分析,得到整体结构的破坏特征和易损位置,分析适用于高墩大跨连续刚构桥的损伤指标。对高墩大跨连续刚构桥进行整体结构的地震易损性分析时,采用应变作为墩柱损伤指标,位移作为支座损伤指标,绘制了基于整体性能的全桥易损性曲线。  相似文献
5.
Assessment of seismic design response factors of concrete wall buildings   总被引:1,自引:1,他引:1  
To verify the seismic design response factors of high-rise buildings, five reference structures, varying in height from 20- to 60-stories, were selected and designed according to modern design codes to represent a wide range of concrete wall structures. Verified fiber-based analytical models for inelastic simulation were developed, considering the geometric nonlinearity and material inelasticity of the structural members. The ground motion uncertainty was accounted for by employing 20 earthquake records representing two seismic scenarios, consistent with the latest understanding of the tectonic setting and seismicity of the selected reference region (UAE). A large number of Inelastic Pushover Analyses (IPAs) and Incremental Dynamic Collapse Analyses (IDCAs) were deployed for the reference structures to estimate the seismic design response factors. It is concluded that the factors adopted by the design code are adequately conservative. The results of this systematic assessment of seismic design response factors apply to a wide variety of contemporary concrete wall buildings with various characteristics.  相似文献
6.
7.
A reliable performance of anti‐seismic devices when the upper‐structure is subjected to strong biaxial seismic excitation is of vital importance to ensure the latter doesn't reach critical behavior. U‐shaped steel dampers are hysteretic devices used to dissipate the earthquake‐induced energy of base‐isolated structures. In the framework of performance‐based design, which is gaining more and more recognition, it is of particular importance to assess the performance of base‐isolated structures with such dampers under different intensity levels of bidirectional ground motion. To achieve this goal, an analytical model able to simulate the bidirectional displacement response of an isolation system is adopted. Incremental dynamic analysis (IDA) is used to obtain the relation between the earthquake‐induced bidirectional damage of U‐shaped steel dampers and different intensity levels of the considered records. The performance of the dampers is categorized into 5 levels delimited by 4 limit states for which fragility curves are derived. The results obtained using the bidirectional approach are quantitatively compared to those given by employing an in‐plane model (widely used in current design practices in Japan) with the purpose of assessing whether the latter provides unconservative estimates of the performance of the dampers. The main conclusion is that, for large seismic intensities, the safety margin against fracture of the dampers is significantly overestimated when an in‐plane model is adopted. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献
8.
As a result of population growth and consequent urbanization, the number of high‐rise buildings is rapidly growing worldwide resulting in increased exposure to multiple‐scenario earthquakes and associated risk. The wide range in frequency contents of possible strong ground motions can have an impact on the seismic response, vulnerability and limit states definitions of RC high‐rise wall structures. Motivated by the pressing need to derive more accurate fragility relations to be used in seismic risk assessment and mitigation of such structures, a methodology is proposed to obtain reliable, Seismic Scenario‐Structure‐Based (SSSB) definitions of limit state criteria. A 30‐story wall building, located in a multi‐seismic scenario study region, is utilized to illustrate the methodology. The building is designed following modern codes and then modeled using nonlinear fiber‐based approach. Uncertainty in ground motions is accounted for by the selection of forty real earthquake records representing two seismic scenarios. Seismic scenario‐based building local response at increasing earthquake intensities is mapped using Multi‐Record Incremental Dynamic Analyses (MRIDAs) with a new scalar intensity measure. Net Inter‐Story Drift (NISD) is selected as a global damage measure based on a parametric study involving seven buildings ranging from 20 to 50 stories. This damage measure is used to link local damage events, including shear, to global response under different seismic scenarios. While the study concludes by proposing SSSB limit state criteria for the sample building, the proposed methodology arrives at a reliable definition of limit state criteria for an inventory of RC high‐rise wall buildings under multiple earthquake scenarios. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献
9.
Controlled rocking steel braced frames (CRSBFs) are low‐damage self‐centring lateral force resisting systems. Previous studies have shown that designing the energy dissipation (ED) and post‐tensioning (PT) in CRSBFs using a response modification factor of R=8 can prevent collapse of structures during earthquakes beyond the design level. However, designers have unique control over the hysteretic behaviour of the system, even after the response modification factor is selected. Additionally, recent studies have suggested that CRSBFs could also be designed using R>8 while still satisfying performance limits. This paper examines how the response modification factor and the design of the ED and PT influence the collapse performance of CRSBFs with three and six storeys where collapse occurs because of over‐rotation of the base rocking joint. In addition, the influence of using an additional rocking joint above the base to mitigate higher‐mode forces is evaluated for a 12‐storey frame. A total of 18 different designs are considered for the three buildings using different ED and PT design parameters, including different response modification factors. A suite of 44 ground motions is scaled until at least 50% of the records cause collapse, and fragility curves are generated using the truncated incremental dynamic analysis curves. The results from two different assessment methodologies show that the parameters selected have a marked influence on the collapse performance of a CRSBF. Nevertheless, even CRSBFs designed using R>8 or without supplemental ED can have acceptably low probabilities of collapse, provided that the frame members are designed to remain elastic. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献
10.
A series of scalar and vector intensity measures is examined to determine their suitability within the seismic risk assessment of liquid storage tanks. Using a surrogate modelling approach on a squat tank that is examined under both anchored and unanchored support conditions, incremental dynamic analysis is adopted to generate the distributions of response parameters conditioned on each of the candidate intensity measures. Efficiency and sufficiency metrics are used in order to perform the intensity measure evaluation for individual failure modes, while a comparison in terms of mean annual frequency of exceedance is performed with respect to a damage state that is mutually governed by the impulsive and convective modes of the tank. The results reveal combinations of spectral acceleration ordinates as adequate predictors, among which the average spectral acceleration is singled out as the optimal solution. The sole exception is found for the sloshing‐controlled modes of failure, where mainly the convective period spectral acceleration is deemed adequate to represent the associated response due to their underlying linear relationship. A computationally efficient method in terms of site hazard analysis is finally proposed to serve in place of the vector‐valued intensity measures, providing a good match for the unanchored tank considered and a more conservative one for the corresponding anchored system.  相似文献
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