共查询到20条相似文献，搜索用时 31 毫秒
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采用地震工程开源模拟软件OpenSees（Open System for Earthquake Engineering Simulation）对CFRP（Carbon Fiber Reinforced Polymer,碳纤维增强复合材料）布加固高强钢筋混凝土方柱的抗震性能进行了数值分析。采用Steel02Material和Concrete02Material材料本构模型模拟了CFRP布加固高强混凝土方柱的抗震性能;在此基础上,进一步研究了轴压比和剪跨比这2个因素对试件抗震性能的影响。将所得数值分析结果与相同条件下的试验结果对比后发现：基于Steel02 Material和Concrete02 Material材料本构,利用OpenSees,可以较好地模拟CFRP布加固高强混凝土方柱的抗震性能,并且与试验结果（滞回曲线、骨架曲线、水平承载力和位移延性系数）能够较好地吻合,从而说明该数值分析方法还可以准确地反映出轴压比和剪跨比对高强混凝土柱抗震性能的影响规律。 相似文献
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Non-linear seismic behavior of structures with limited hysteretic energy dissipation capacity 总被引：1，自引：0，他引：1
Pierino Lestuzzi Youssef Belmouden Martin Trueb 《Bulletin of Earthquake Engineering》2007,5(4):549-569
This paper investigates the non-linear seismic behavior of structures such as slender unreinforced masonry shear walls or
precast post-tensioned reinforced concrete elements, which have little hysteretic energy dissipation capacity. Even if this
type of seismic response may be associated with significant deformation capacity, it is usually not considered as an efficient
mechanism to withstand strong earthquakes. The objective of the investigations is to propose values of strength reduction
factors for seismic analysis of such structures. The first part of the study is focused on non-linear single-degree-of-freedom
(SDOF) systems. A parametric study is performed by computing the displacement ductility demand of non-linear SDOF systems
for a set of 164 recorded ground motions selected from the European Strong Motion Database. The parameters investigated are
the natural frequency, the strength reduction factor, the post-yield stiffness ratio, the hysteretic energy dissipation capacity
and the hysteretic behavior model (four different hysteretic models: bilinear self-centring, with limited or without energy
dissipation capacity, modified Takeda and Elastoplastic). Results confirm that the natural frequency has little influence
on the displacement ductility demand if it is below a frequency limit and vice versa. The frequency limit is found to be around
2 Hz for all hysteretic models. Moreover, they show that the other parameters, especially the hysteretic behavior model, have
little influence on the displacement ductility demand. New relationships between the displacement ductility demand and the
strength reduction factor for structures having little hysteretic energy dissipation capacity are proposed. These relationships
are an improvement of the equal displacement rule for the considered hysteretic models. In the second part of the investigation,
the parametric study is extended to multi-degree-of-freedom (MDOF) systems. The investigation shows that the results obtained
for SDOF systems are also valid for MDOF systems. However, the SDOF system overestimates the displacement ductility demand
in comparison to the corresponding MDOF system by approximately 15%. 相似文献
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Karsten Bolding Hans Burchard Thomas Pohlmann Adolf Stips 《Continental Shelf Research》2002,22(18-19)
The aim of this study is to intervalidate observations and numerical simulation results for the turbulent dissipation rate under strong wind conditions in the Northern North Sea during one week in October 1998. The observations were obtained by spatially and temporally averaging measurements of small-scale shear with a free-falling shear probe. The 1D numerical model used for this study is based on a state-of-the-art two-equation k− turbulence model with an algebraic second-moment closure scheme. It is discussed by means of annual and seasonal model simulations how the influence of heat and salt advection and internal waves can be accounted for. After these precautions, the agreement between observations and simulations of the turbulent dissipation rate are fairly good. Remaining differences cannot only be explained by problems such as undersampling and noise level, but also by idealising model assumptions. 相似文献
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基于损伤塑性模型的砌体墙体非线性有限元分析 总被引：2，自引：0，他引：2
为了研究砌体墙体用钢结构加固后的力学性能,需要提供较准确的砌体墙体非线性计算,考虑到砌体与混凝土的材料性质具有相似性,将混凝土损伤塑性模型经修正后应用于砌体数值模拟,实现对砌体墙体的非线性有限元分析。通过与水平加载试验结果对比,验证了有限元模型的正确性。探讨了损伤塑性模型中的粘性系数、膨胀角、砌体本构关系中的初始弹性模量、受拉应力应变关系对计算结果的影响。结果表明：粘性系数和膨胀角对抗剪承载力、峰值位移及下降段性能均有较大影响,而对初始刚度影响很小;随着初始弹性模量的增大,砌体墙体抗剪承载力随之提高,但峰值位移无明显变化;受拉应力应变方程中待定系数的取值,对抗剪承载力及峰值位移影响较大。 相似文献
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考虑SSI效应储油罐的子结构实验方法与数值模拟 总被引：1，自引：0，他引：1
提出了应用振动台子结构试验方法来研究考虑土-结构相互作用（SSI）效应储罐的抗震性能,该方法将土体简化为双自由度八参量集总参数模型进行模拟,储罐作为试验子结构应用振动台加载,两部分联机完成振动台子结构试验。该方法能完成大比例尺储罐试验,具有传统试验方法难以比拟的优势。然后,通过数值模拟分析了SSI效应对储罐动力响应的影响。分别研究了不同储液高度和不同地基刚度对储罐位移和加速度响应的影响。研究结果表明：考虑SSI效应时,罐体位移响应和加速度响应均有所减小,土质越软,效果越明显;随着储液高度的增高,位移、加速度反应呈现减小趋势。 相似文献
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1 Introduction Structural retro?t techniques (Roberts, 2005), such as restrainers, concrete shear keys, steel jackets, CFRPshells, base isolators, or dampers have been widely studied and implemented in actual structures based on the experiences learned from past earthquakes. In the Chi-Chi earthquake (EERI, 2001), the damage to simply-supported PCI girder bridges provided a different view from which to examine the function of a rubber bearing system for simply- supported bridges (NCREE,… 相似文献
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The nuclear accident at Fukushima Daiichi in March 2011 has led the nuclear community to consider seismic isolation for new large light water and small modular reactors to withstand the effects of beyond design basis loadings, including extreme earthquakes. The United States Nuclear Regulatory Commission is sponsoring a research project that will quantify the response of low damping rubber (LDR) and lead rubber (LR) bearings under loadings associated with extreme earthquakes. Under design basis loadings, the response of an elastomeric bearing is not expected to deviate from well‐established numerical models, and bearings are not expected to experience net tension. However, under extended or beyond design basis shaking, elastomer shear strains may exceed 300% in regions of high seismic hazard, bearings may experience net tension, the compression and tension stiffness will be affected by isolator lateral displacement, and the properties of the lead core in LR bearings will degrade in the short‐term because of substantial energy dissipation. New mathematical models of LDR and LR bearings are presented for the analysis of base isolated structures under design and beyond design basis shaking, explicitly considering both the effects of lateral displacement and cyclic vertical and horizontal loading. These mathematical models extend the available formulations in shear and compression. Phenomenological models are presented to describe the behavior of elastomeric isolation bearings in tension, including the cavitation and post‐cavitation behavior. The elastic mechanical properties make use of the two‐spring model. Strength degradation of LR bearing under cyclic shear loading due to heating of lead core is incorporated. The bilinear area reduction method is used to include variation of critical buckling load capacity with lateral displacement. The numerical models are coded in OpenSees, and the results of numerical analysis are compared with test data. The effect of different parameters on the response is investigated through a series of analyses. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Tectonic inversion is a common phenomenon in island arc settings, especially in back‐arc basins. The reactivation of normal faults as thrusts, triggered by tectonic inversion, produces typical inversion fault‐related folds and thrusts in the hangingwall. These hangingwall inversion geometries are affected by two factors: the geometry of the underlying master fault and the angle of inclined simple shear relative to the regional dip of strata, in the case that the deformation is approximated by simple shear. This study employed numerical simulations to analyse the influence of the antithetic shear angle on the geometry of the hangingwall and displacement along the master fault. The simulation results reveal that a steeply inclined shear vector during extension produces a narrow, steep‐sided half‐graben, whereas a gently inclined shear produces a wide, open basin. After tectonic inversion, a tight anticline is formed under steeply inclined shear, whereas an open anticline is formed under gently inclined shear. Antithetic shear results in reduced total displacement along the master fault, and the greater the angle between the shear direction and the regional dip, the greater the displacement along the master fault. Because the deformation geometry of syn‐extension layers is affected by extension followed by contraction, a change in the shear angle during tectonic inversion produces a wide variety of deformation geometries. Comparison of the simulation results with the results of analogue modelling suggests that the shear angle decreases by 5° during the transition from extension to tectonic inversion and that such a change may be commonly observed in natural geological structures. These results highlight the benefits of numerical simulations, which can be used to readily examine a variety of constraining parameters and thereby lead to a better understanding of the mechanism of hangingwall deformation, avoiding erroneous estimates of the amount of fault displacement. 相似文献
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为研究非对称配钢钢骨混凝土柱的抗震性能,基于12根T形配钢钢骨混凝土柱的拟静力试验研究进行非线性数值模拟,了解其破坏机制、承载力、延性及耗能能力,探讨轴压比、配钢率、剪跨比对抗震性能的影响。结果表明,低周反复荷载作用下T形配钢钢骨混凝土柱滞回曲线饱满,具有良好的延性和耗能能力。在峰值荷载前,数值模拟结果与试验结果吻合较好。轴压力在一定范围内提高了试件承载力,但降低了延性;增大配钢率能提高试件的承载力、刚度和延性,使得峰值荷载后试件的性能退化趋于平缓;剪跨比对试件破坏形态有显著影响,随剪跨比的增大试件延性性能提高。 相似文献
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为了提高采用板式橡胶支座的斜梁桥横向抗震能力,揭示其在不同设计参数下的横向抗震行为,考虑板式橡胶支座的滑移、钢筋混凝土挡块的滞回力学性能、桥台-背土效应等非线性因素,采用OpenSEES建立某连续斜梁桥的三维分析模型,提出支座位移评价指标、主梁平面转角指标、墩柱曲率延性指标和抗剪指标,研究不同挡块强度和间隙组合下桥梁的横向抗震性能。研究表明:同时增大挡块强度和间隙,总体上会降低支座的横向变形,但会增加其纵向变形;挡块强度越高,主梁的横向位移有所下降,但平面转角越大,对两侧桥台处的支座抗剪越不利;挡块强度越高,间隙越小,墩柱越有可能进入弹塑性状态。在本文桥例中,当挡块强度取40%支反力,间隙取0.08m时,所有抗震指标都可满足规范要求。 相似文献
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This study presents a framework for numerical simulations based upon micromechanical parameters in modeling progressive failures
of heterogeneous rock specimens under compression. In our numerical simulations, a Weibull distribution of the strength and
elastic properties of the finite elements is assumed, and the associated Weibull parameters are estimated in terms of microstructural
properties, such as crack size distribution and grain size, through microscopic observations of microcracks. The main uncertainty
in this procedure lies on the fact that various ways can be used to formulate a ``microcrack size distribution' in relating
to the Weibull parameters. As one possible choice, the present study uses the number of counted cracks per unit scanned volume
per grain size to formulate the crack distributions. Finally, as a tool, the Rock Failure Process Analysis code (RFPA2D) is adopted for simulating the progressive failure and microseismicity of heterogeneous rocks by using an elastic-damage
finite-element approach. To verify our framework, compression tests on marble specimens are conducted, and the measured acoustic
emissions (AE) are compared with those predicted by the numerical simulations. The mode of failure, compressive strength and
AE pattern of our simulations basically agree with experimental observations. 相似文献
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《地震工程与结构动力学》2018,47(6):1440-1459
Displacement‐based assessment procedures require as input reliable estimates of the deformation capacity of all structural elements. For unreinforced masonry (URM) walls, current design codes specify the in‐plane deformation capacity as empirical equations of interstory drift. National codes differ with regard to the parameters that are considered in these empirical drift capacity equations, but the inhomogeneity of datasets on URM wall tests renders it difficult to validate the hypotheses with the currently available experimental data. This paper contributes to the future development of such empirical relationships by investigating the sensitivity of the drift capacity to the shear span, the aspect ratio, the axial load ratio, and the size of the wall. For this purpose, finite element models of URM walls are developed in Abaqus/Explicit and validated against a set of experimental results. The results show that the axial load ratio, the shear span, and the wall size are among the factors that influence the drift capacity the most. Empirical equations are mainly derived from test results on small walls, and the numerical results suggest that this can lead to a significant overestimation of the drift capacity for larger walls. 相似文献
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为提高混凝土剪力墙受弯性能计算的准确度,开展强震下混凝土剪力墙受弯性能试验研究。选取1个混凝土剪力墙对比试件和3个测试试件作为研究对象,对试件施加垂直荷载和水平荷载,模拟强烈地震作用力。试验前期准备工作完成后,建立分离式有限元模型,通过计算混凝土在受压和受拉状态下的损伤弹塑性刚度,完成对有限元模型中混凝土塑性损伤分析,在此基础上,计算混凝土剪力墙受弯承载力。利用有限元模型对3个测试试件进行模拟试验,结果表明,强烈地震后3个试件的荷载-位移曲线均与实际位移值接近,且混凝土剪力墙受弯承载力试验结果与实际值的误差在2%以内,表明试验研究方法具有一定的可行性,数值模拟结果较为准确。 相似文献
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This paper aims to provide a guideline for numerical modeling of reinforced concrete (RC) frame elements for the seismic performance assessment of a structure. Several types of numerical models of RC frame elements are available in nonlinear structural analysis packages. Because the numerical models are formulated based on different assumptions and theories, the models' accuracy, computing time, and applicability vary, which poses a great difficulty to practicing engineers and limits their confidence in the analysis results. In this study, the applicability of five representative numerical models of RC frame elements is evaluated through comparison with 320 experimental results available from the Pacific Earthquake Engineering Research column database. The accuracy of a numerical model is evaluated according to its initial stiffness, peak strength, and energy dissipation capacity of the global responses. In addition, a parametric study of a cantilever RC column subjected to earthquake excitation is carried out to systematically evaluate the consequence of the adopted numerical models on the maximum inelastic structural responses. It is found from this study that the accuracy of the numerical models is sensitive to shear force demand–capacity ratio. If a structural period is short and the structure is shear critical, the use of numerical models that can explicitly capture the shear deformation and failure is suggested. If the structural period is long, the selection of a numerical model does not greatly influence the global response of the structure. The paper also presents statistical parameters of each numerical model, which can be used for probabilistic seismic performance assessment. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Newmark永久位移是评价边坡在地震时稳定性的一个重要指标,近年来广泛应用于地震边坡危险性评价中。传统Newmark永久位移法在计算临界加速度时假定其为常数,未考虑滑动面上抗剪强度参数的变化,过低估计了边坡的永久位移。为了解决这一问题,本文从岩土结构理论获得思路,详细分析滑块底面抗剪强度参数在地震中的变化过程,以边坡震动过程中黏聚力逐步丧失为基本思路,在黏聚力符合一定概率分布的基础上,提出了一种利用蒙特卡罗法模拟其动态减小过程从而实现临界加速度动态变化的计算方法。经过算例计算,黏聚力和临界加速度体现了地震过程中边坡滑块黏聚力和临界加速度的动态变化,位移大小符合地震边坡实际位移的常规数值。本文提出的蒙特卡罗法实现动态黏聚力和动态临界加速度的计算过程与地震时程相对应,不仅在一定程度上解决了抗剪强度参数的动态变化问题,还解决了传统Newmark位移计算中永久位移比实际位移偏小的问题。 相似文献
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Experimental research and finite element analysis of bridge piers failed in flexure-shear modes 总被引：2，自引：1，他引：1
In recent earthquakes, a large number of reinforced concrete （RC） bridges were severely damaged due to mixed flexure-shear failure modes of the bridge piers. An integrated experimental and finite element （FE） analysis study is described in this paper to study the seismic performance of the bridge piers that failed in flexure-shear modes. In the first part, a nonlinear cyclic loading test on six RC bridge piers with circular cross sections is carried out experimentally. The damage states, ductility and energy dissipation parameters, stiffness degradation and shear strength of the piers are studied and compared with each other. The experimental results suggest that all the piers exhibit stable flexural response at displacement ductilities up to four before exhibiting brittle shear failure. The ultimate performance of the piers is dominated by shear capacity due to significant shear cracking, and in some cases, rupturing of spiral bars. In the second part, modeling approaches describing the hysteretic behavior of the piers are investigated by using ANSYS software. A set of models with different parameters is selected and evaluated through comparison with experimental results. The influences of the shear retention coefficients between concrete cracks, the Bauschinger effect in longitudinal reinforcement, the bond-slip relationship between the longitudinal reinforcement and the concrete and the concrete failure surface on the simulated hysteretic curves are discussed. Then, a modified analysis model is presented and its accuracy is verified by comparing the simulated results with experimental ones. This research uses models available in commercial FE codes and is intended for researchers and engineers interested in using ANSYS software to predict the hysteretic behavior of reinforced concrete structures. 相似文献
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针对结构隔震装置在较大的倾覆力作用下抗拉能力不足的问题,提出了一种带有楔形分离式轨道的新型滑移支座。新支座能够承受上部结构传递的荷载以及适应较大水平位移,同时利用楔形轨道与楔形滑块之间的相互作用提供抗拉能力。采用通用有限元程序ABAQUS建立了支座的三维实体有限元模型,对其抗压、抗拉、压剪和拉剪力学性能进行数值模拟研究,同时考虑了楔形角度的改变对支座力学性能的影响。通过分析表明:在竖向新支座具有较好的抗压和抗拉能力,抗拉性能受楔形角度的影响较大,角度大于60°时,支座的抗拉能力随着角度的减小不断提升;而当角度减小到60°时,楔形滑块与上部连接部分出现薄弱点,导致支座的抗拉能力开始降低。在压剪与拉剪的作用下,支座水平向的滞回曲线比较饱满,具有较好的水平向摩擦耗能能力且能够适应较大的水平位移。 相似文献
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以一字形竖缝耗能预制剪力墙作为研究对象,设计了3个装配式剪力墙试件及1个现浇剪力墙对比试件,进行低周往复荷载试验,并对破坏墙体进行CFRP加固,再次进行拟静力试验。试件变化参数包括轴压比、混凝土强度等级及配筋率,对比分析加固前后试件滞回性能、刚度退化、承载力和耗能能力等性能。试验结果表明,与现浇剪力墙相比,一字形竖缝耗能预制剪力墙工作性能良好,阻尼器屈服耗能提高了试件整体工作性能;CFRP加固可有效抑制墙体斜裂缝的发展,对墙体承载力及耗能能力均有显著改善作用;各试件均满足剪力墙弹塑性层间位移角限值要求,延性较好;试件整体表现出良好的抗震性能。 相似文献