共查询到20条相似文献，搜索用时 578 毫秒
1.
抗震规范应用强度折减系数的现状及分析 总被引：5，自引：1，他引：4
世界上大多数的抗震规范都采用了基于强度的设计方法,强度折减系数是基于强度的抗震设计中确定设计地震力的关键因素,提高强度折减系数的可靠性已经被认为是提高现有抗震规范可靠性的有效途径。本文主要介绍了抗震研究处于世界先进水平的美国(UBC97)、欧洲(EC8)、日本、墨西哥、加拿大、中国等国家抗震规范中强度折减系数取值的有关规定,然后给出了各国学者关于规范规定的强度折减系数的一些重要讨论和分析,最后指出了世界各国应用强度折减系数过程中存在的不足,指出了需进一步研究的问题。 相似文献
2.
将钢框架结构按其性能划分为使用良好、人身安全、防止倒塌三个水平,并用层间侧移角予以量化采用钢框架的最大层侧移模式来确定其目标侧移曲线在等效线性化的前提下,由等效位移用弹性位移反应谱求出等效周期,然后对构件进行刚度设计和承载力设计用静力弹塑性分析方法对结构进行分析,校核其实际侧移曲线与满足性能目标的侧移曲线是否一致.采用... 相似文献
3.
耗能梁段作为偏心支撑结构的耗能元件,在大震作用下通过弹塑性变形吸收地震能量,保护主体结构处于弹性受力状态。现行规范基于强度的设计理论,为了保证耗能梁段进入塑性或破坏,梁柱构件需要进行放大内力设计,导致截面过大,而且基于强度的设计方法很难保证结构的整体破坏状态。目前,抗震设计越来越重视基于性能的设计思想,该方法能够评估结构的弹塑性反应。对于高强钢组合偏心支撑,其中耗能梁段和支撑采用Q345钢,框架梁柱采用Q460或者Q690高强度钢材,高强钢不仅带来良好的经济效益,而且能够推广高强钢在抗震设防区的应用。利用基于性能设计方法设计了4种不同形式的高强钢组合偏心支撑钢框架,包括K形、Y形、V形和D形,考虑4层、8层、12层和16层的影响。通过Pushover分析和非线性时程分析评估该结构的抗震性能,研究结果表明:4种形式的高强钢组合偏心支撑钢框架具有类似的抗震性能,在罕遇地震作用下,几乎所有耗能梁段均参与耗能,而且层间侧移与耗能梁段转角沿高度分布较为均匀。其中:D形偏心支撑具有最大的抗侧刚度,但延性较差,而Y形偏心支撑的抗侧刚度最弱,但延性最佳。 相似文献
4.
5.
K形高强钢组合偏心支撑(K-HSS-EBF)是指耗能连梁和支撑采用Q345钢,而框架梁、框架柱采用高强度钢(如Q460)。为研究其在罕遇地震作用下的抗震性能,在试验研究的基础上,采用直接基于位移的抗震设计方法设计了5层、8层和12层算例,分别进行静力推覆分析和动力弹塑性分析,研究高强钢组合偏心支撑钢框架在罕遇地震作用下层间侧移分布和破坏模式。研究结果表明:直接基于位移的抗震设计方法设计的算例在罕遇地震作用下,结构的层间侧移满足我国现行抗震规范的要求,结构呈理想的渐进式梁铰屈服机构,并证明该设计方法的合理性和可靠性。 相似文献
6.
Modeling level selection for seismic analysis of concrete‐filled steel tube/moment‐resisting frames by using fragility curves 
下载免费PDF全文
下载免费PDF全文 The seismic behavior of plane moment‐resisting frames (MRFs) consisting of I steel beams and concrete‐filled steel tube (CFT) columns is investigated in this study. More specifically, the effect of modeling details of each individual component of CFT‐MRFs, such as the composite CFT columns, the beam‐column connections, the panel zones, and the steel I beams on their seismic behavior, is studied through comparisons against available experimental results. Then, fragility curves are constructed for three typical CFT‐MRFs, designed according to European codes, for various levels of modeling sophistication through nonlinear time‐history analyses. On the basis of these fragility curves, one can select the appropriate modeling level of sophistication that can lead to the desired seismic behavior for a given seismic intensity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
8.
为讨论利用纤维梁柱单元进行钢筋混凝土桥墩地震反应分析的建模方法,分别以4个悬臂式单柱墩和1个双柱墩拟静力加载试验,以及1个悬臂式单柱墩的振动台试验结果为依据,基于OpenSees数值分析平台建立了桥墩的地震反应分析模型。通过改变单元数量,分析了基于力的纤维梁柱单元和基于位移的纤维梁柱单元对桥墩地震反应的模拟精度。结果表明:对悬臂式单柱墩的拟静力和振动台试验,可沿墩高仅建立1个基于力的纤维梁柱单元,并在墩底串联1个考虑纵筋塑性渗透和粘结滑移的转动弹簧单元,即可获得很好的模拟结果。当采用基于位移的纤维梁柱单元时,应沿墩高至少建立2个单元,且塑性铰区至少有1个,才能保证获得较高的模拟精度。对双柱墩拟静力试验,采用基于力的纤维梁柱单元建模,沿每个墩高建立2个单元即可;以基于位移的纤维梁柱单元建模,建议沿每个墩高建立3个单元,且其中2个单元布置在塑性铰区。当数值模型可对静力滞回曲线取得很好的模拟结果后,该模型一般可对动力作用下墩顶最大位移和墩底最大剪力进行较为准确的模拟,但对墩顶残余位移的模拟精度无法保证。 相似文献
9.
M. Ataur Rahman Sri Sritharan 《地震工程与工程振动(英文版)》2006,5(2):285-296
The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability. 相似文献
10.
11.
12.
A displacement-based design procedure is proposed for proportioning hysteretic damped braces in order to attain, for the in-plan least seismic capacity direction and a specific level of seismic intensity, a designated performance level of a reinforced concrete (r.c.) irregular framed building to be retrofitted. To this end, a computer code for the nonlinear static analysis of spatial frames is developed to obtain the pushover curve for an assigned in-plan direction of the seismic loads. The town hall of Spilinga (Italy), a two-storey r.c. framed structure with an L-shaped plan built at the beginning of the 1960s, has been considered as case study. Four alternative structural solutions are examined, derived from the first one by the insertion of hysteretic damped braces, considering: the extended N2 and the extended pushover methods combined with a proportional and an inversely proportional in-plan stiffness distributions of hysteretic damped braces. To check the effectiveness and reliability of the design procedure, the nonlinear static response of the unbraced and damped braced frames is compared for different in-plan directions of the seismic loads. Frame members are simulated with a lumped plasticity model, including a flat surface modeling of the axial load-biaxial bending moment elastic domain, while the behavior of a hysteretic damped brace is idealized through the use of a bilinear law. Vulnerability index domains are adopted to estimate the directions of least seismic capacity at the ultimate (i.e. life-safety and collapse prevention) limit states prescribed by Italian and European seismic codes. 相似文献
13.
14.
Approximate formulae for the estimation of lateral displacements at first yielding of plane steel frames under seismic excitations are provided for use in a performance based seismic design and more particularly, in a direct displacement based seismic design of these structures. These formulae, which are functions of the geometrical and design properties of the frames, are derived on the basis of seismic response data obtained with the aid of extensive dynamic inelastic analyses involving 36 moment resisting and 36 x-braced plane steel frames with steel grade S235, S275 and S355 under 84 ordinary seismic ground motions. Comparison of the proposed formulae against other simpler existing formulae, reveals the higher accuracy of the proposed ones. 相似文献
15.
The performance of force-based and displacement-based seismic assessment methods for the life-safety limit state check of out-of-plane loaded unreinforced masonry walls is evaluated on the basis of refined numerical simulations. For this purpose, a discrete element model of a vertically spanning wall is built and validated against experimental results from static and dynamic test conditions. The model is then analysed for a large range of wall configurations. For each configuration, a static pushover analysis and a series of incremental dynamic analyses are run, the latter permitting to determine the capacity of the wall under dynamic loading. The accuracy of the assessment methods in predicting the acceleration at which the walls collapse is evaluated. It is found that the displacement-based method is more accurate, robust, and safe than the force-based method. The comparison also shows that for walls characterised by a relatively high ratio of axial load to Euler's critical load, both assessment methods lead to an overestimation of the wall capacity. As a remedy, a modification to the methods based on a recently developed mechanical model is put forward and tested. For the force-based method, it is additionally suggested to set for walls with relatively high overburden ratios the behaviour factor equal to 1. To ensure reproducibility of this study, all input and output files of the numerical simulations are made publicly available. 相似文献
16.
A. J. Kappos I. G. Gidaris K. I. Gkatzogias 《Bulletin of Earthquake Engineering》2012,10(4):1237-1266
Currently available displacement-based design (DBD) procedures for bridges are critically evaluated with a view to identifying extensions and/or modifications of the procedure, for it to be applicable to final design of a fairly broad class of bridges. An improved direct DBD procedure is presented, including a suite of comprehensive design criteria and proper consideration of the degree of fixity of the pier top. The design of an overpass bridge (originally designed to a current European Code), applying the improved ‘direct’ displacement-based design (DDBD) procedure is presented and both ‘conventional’ and displacement-based designs are assessed using non-linear response-history analysis (NLRHA); comparisons are made in terms of both economy and seismic performance of the different designs. It is seen that DDBD provided a more rational base shear distribution among piers and abutments when compared to the force-based design procedure and adequately captured the displacement pattern, closely matching the results of the more rigorous NLRHA. 相似文献
17.
Displacement response spectrum (DRS), as the input, is of great significance to the displacement-based design just like the acceleration response spectrum to the traditional force-based design. Although the procedure of performance-based, in particular the displacement-based design has achieved considerable development, there is not a general DRS covering an enough long period range for common seismic design yet. This paper develops a systematic ground motion data processing procedure for the purpose of correcting the noise in the earthquake records and generating consistent DRS for seismic design. An adaptive algorithm is proposed to determine the cutoff frequency of the high-pass digital filter. The DRS of more than 500 recorded earthquake ground motions are generated and they are classified into three groups according to the ratio of the peak ground acceleration to the peak ground velocity (A/V) and/or the ratio of the peak ground velocity to the peak ground displacement (V/D). In each group, all the ground motions are normalized with respect to a selected scaling factor. Their corresponding DRS are obtained and then averaged to get the mean and standard deviation DRS, which can be used for both deterministic and probabilistic displacement-based design. 相似文献
18.
Aristidis V. Asimakopoulos Dimitris L. Karabalis Dimitri E. Beskos 《地震工程与结构动力学》2007,36(14):2171-2188
A procedure for treating the P– Δ effect in the direct displacement‐based seismic design of regular steel moment resisting frames with ideal elastoplastic material behaviour is proposed. A simple formula for the yield displacement amplification factor as a function of ductility and the stability coefficient is derived on the basis of the seismic response of an inelastic single degree‐of‐freedom system taking into account the P– Δ effect. Extensive parametric seismic inelastic analyses of plane moment resisting steel frames result in a simple formula for the dynamic stability coefficient as a function of the number of stories of a frame and the column to beam stiffness ratio. Thus, the P– Δ effect can be easily taken into account in a direct displacement‐based seismic design through the stability coefficient and the yield displacement amplification factor. A simple design example serves to illustrate the application of the proposed method and demonstrate its merits. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
19.
钢框架结构直接基于位移抗震性能设计的非迭代法 总被引：1，自引：1，他引：0
为使直接基于位移的抗震性能设计方法更加简便准确,本文采用一种直接基于位移的非迭代抗震设计方法对钢框架结构进行设计。该方法首先考虑结构的非弹性反应确定等效弹性反应谱和弹塑性反应谱,并建立了使用Newmark-Hall变形折减系数的能力谱的明确表达式。采用能力-需求图方法,确定了结构需要的目标位移与延性、谱位移和谱加速度之间关系的明确表示式,得到结构的刚度和设计基底剪力,进而确定构件截面,完成结构设计。对五层两跨平面钢框架结构进行了直接基于位移的抗震性能设计,设计过程简便,无需迭代程序,不需画出反应谱,通过时程分析验证了设计结果的精确性。本文研究表明:直接基于位移的非迭代抗震设计方法是一种简便、高效、精确的抗震性能设计方法。 相似文献
20.
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