共查询到18条相似文献，搜索用时 140 毫秒
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为研究基础隔震结构抗连续倒塌性能,以备用荷载路径法为基础,采用静力非线性Pushdown方法和静力线性方法对一栋典型的收进式竖向不规则钢筋混凝土基础隔震结构进行分析,从备用荷载路径的抗连续倒塌机制和需求能力比两个角度研究竖向不规则钢筋混凝土基础隔震结构的抗连续倒塌性能,为基础隔震结构抗连续倒塌设计提供参考;为进一步研究结构布置形式不规则性以及裙楼和塔楼层数变化对竖向不规则基础隔震抗连续倒塌性能的影响,分别建立塔楼布置不同、裙楼与塔楼层数变化的模型进行对比研究。研究表明:除角柱失效工况自身无法产生悬链线机制外,其余底层框架柱失效工况中备用荷载路径在整个推覆倒塌过程中均表现出明显的悬链线机制;当隔震支座失效时,由于隔震层水平刚度小,相邻支座无法提供足够的侧向约束作用而难以形成明显的悬链线机制;增加结构冗余度和备用荷载路径中参与荷载传递的构件数量可以有效提高剩余结构抗连续倒塌能力;除角柱和角支座外,隔震支座失效工况DCR值普遍大于对应位置底层框架柱失效工况,备用荷载路径中某些构件的失效风险相对较大。 相似文献
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增大柱端抗弯承载力是抗震"能力设计"措施中引导钢筋混凝土框架结构形成梁铰型有利耗能机构的关键措施。本文以6层确定性钢筋混凝土框架结构为分析对象,通过结构易损性分析评估了不同强柱系数取值对钢筋混凝土框架结构抗震性能的影响。结构易损性分析表明增大柱端抗弯承载力是改善结构抗震性能的有效措施,增大强柱系数提高了结构的变形能力,使不同破坏极限状态之间形成较大的"梯度",对防止强烈地震作用下结构的突然倒塌提供了预示。结构易损性曲线对评估结构抗震性能、选用合适的目标强柱系数提供了量化标准。 相似文献
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《世界地震工程》2015,(4)
目前国内外学者将地震倒塌和连续倒塌作为两个独立的领域进行研究,实际上框架结构的倒塌破坏系由二种机理耦合作用所致。针对此问题,采用拆除构件设计法,应用有限元程序ANSYS/LS-DYNA完成了钢筋混凝土框架结构拆除底层关键柱后在地震作用下的倒塌仿真分析,重点研究了层高、跨度、层数和关键柱位置对钢筋混凝土框架结构抗倒塌性能的影响。结果表明:对于平面框架模型,由底层柱脚及梁柱节点区柱端失效破坏引起的柱铰破坏机制,是导致结构倒塌的主要原因。底层中柱失效后,底层迅速转化为柱铰机制,结构在重力作用下失稳坍塌,适当增加层高,减小跨度,增加层数对框架结构在底层关键柱失效后的抗地震倒塌性能有益;对于三维空间框架模型,分析表明,空间框架结构在拆除角柱后框架倒塌破坏最为严重,结构的破坏过程可以概括为3个阶段:(1)弹性阶段;(2)重力作用影响占主导地位的塑性阶段;(3)地震作用占主导地位的塑性阶段。 相似文献
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由于承重结构构件分布不均匀,导致高层建筑框架承重构件间的距离不相等。在地震时,这种不规则分布可能引起加速度共振效应,从而导致建筑失稳。为此,以地震动强度、地震动速度峰值、最大层间位移角为参数指标,分析高层建筑的极限状态,提出基于增量动力地震易损性分析的高层结构抗震加固研究。以某实际工程为试验对象,运用ABAQUS软件构造高层建筑框架结构三维模型,选取多条地震波以及符合场地条件的地震动记录进行验证,绘制地震易损性曲线。结果表明:在高层建筑框架结构中安装阻尼器,可增强结构中各构件的承载力,改善高层建筑抗震性能;增加钢板厚度可提高结构抗震水平,降低极限状态下框架结构IO、LS与CP的超越概率;提高混凝土强度,可改善框架结构抗倒塌性能。高层结构完成抗震加固后,抗震能力由0.91提升至1.01。由此证明,以增量动力分析得到的结构易损性为基础,对建筑易损性较大的地方进行加固、完善,能够改善高层建筑框架结构地震易损性,减少地震灾害损失。 相似文献
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以具体案例为依托,对大跨度轮辐式张弦梁结构的构件重要性进行分析并排序,探讨不同因素对关键构件重要性的影响,基于显示动力积分法模拟关键构件瞬间失效后的结构响应,考察结构在关键构件意外失效时的力学行为。分析结果表明：内环下弦杆、拉索、支座及靠近支座处上弦梁段为关键构件;单独增大上弦截面刚度时,各关键构件重要性随之降低,单独增大垂度、初始预应力时,拉索及支座的重要性随之提高,其余关键构件重要性随之降低;拆除内环下弦杆后,结构缺乏有效的备用荷载路径,内力重分布代价较大,局部区域出现严重变形,其余关键构件失效后,环梁为主要备用荷载路径;各关键构件瞬间失效后结构动力效应明显且不相同,对于此类结构,在分析时应考虑构件失效前的初始状态。 相似文献
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为研究余震对钢框架-中心支撑结构抗震性能的影响，以钢框架-拉链柱式中心支撑结构和传统钢框架-人字形中心支撑结构为例，基于增量动力分析方法，对2种结构在主余震、主震作用下进行地震易损性分析。对比了2种结构地震易损性差异，根据抗倒塌储备系数评价了2种结构的抗倒塌性能。结果表明：余震会增加结构的地震易损性，其影响程度随着地震动强度的变大而增加；与人字形中心支撑结构相比，拉链柱式中心支撑结构在高强度地震下处于重度损伤和倒塌2种极限状态时的失效概率更低，抗倒塌储备系数更大，抗倒塌性能更优。 相似文献
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为了充分反映结构的抗连续倒塌能力,文中基于能量原理,将结构倒塌时消耗能量与屈服时消耗能量之比定义为考虑悬链线效应的结构鲁棒性指标。首先进行一榀1/2缩尺的RC平面框架的连续倒塌试验,得到了具有双峰值点的荷载-位移曲线。基于试验数据对有限元模型进行验证与校准。进一步建立了18个RC平面框架结构数值分析模型,研究了中柱失效、边柱失效及不同梁底部纵向钢筋配筋率、顶部纵向钢筋配筋率等对考虑悬链线效应的结构鲁棒性影响规律。分析结果表明,由于边柱失效的结构无法发挥悬链线效应,鲁棒性较差;而中柱失效后的结构,由于其存在悬链线效应,结构表现出了更好的鲁棒性。结构鲁棒性系数随着梁底部钢筋配筋率的增加而降低,随着梁上部钢筋配筋率的增加而提高,梁上部钢筋配筋率显著影响结构的鲁棒性。本文提出的基于能量的考虑悬链线效应的结构鲁棒性计算方法,为RC框架结构抗连续倒塌设计提供了理论支持。 相似文献
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阻尼器连接填充墙采用黏滞阻尼器与主体框架结构连接,是一种新型填充墙与框架的柔性连接方式,能满足柔性框架结构的大变形需求。为使得阻尼器连接填充墙达到最优的力学性能,结构布置和构件力学参数的选择十分重要,采用有限元软件ABAQUS分别建立了柔性钢框架结构和阻尼器连接填充墙-框架结构的有限元模型,考察不同阻尼系数阻尼器连接填充墙的抗风、抗震和抗倒塌力学行为。数值模拟结果表明,经过对阻尼器阻尼系数优化取值后,阻尼器连接填充墙在风荷载作用下不会开裂且最大应力值仅为嵌砌刚性连接填充墙的1/3,主体结构加速度地震响应可降低48%左右,并能保证墙体在罕遇地震作用下不倒塌。最后给出阻尼器连接填充墙设计流程。 相似文献
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《地震工程与工程振动》2020,(4)
震害表明结构反应修正系数的子项冗余度系数取为1,过高地估计了结构通过备用荷载路径进行内力重分布的抗竖向连续倒塌能力。本文拟分别采用静力Pushdown和动力竖向IDA方法对根据《建筑抗震设计规范》GB50011-2010(2016版)设计的RC框架进行分析,采用损伤强度比DSR作为冗余度系数,并根据倒塌临界值,判定结构在设计荷载作用下是否具有足够的抗倒塌能力。分析结果表明,按VII、VIII度设防设计的结构,冗余度系数均大于1,结构在设计荷载作用下不会发生连续倒塌,但是按VI度设防设计的低层结构冗余度系数小于1,在设计荷载作用下结构会发生连续倒塌。针对VI度设防设计的结构,采用实际的冗余度系数最小值0.69,对结构反应修正系数值进行修正,修正后的数值为2.02。实现在结构地震影响系数曲线中考虑抗连续倒塌能力的影响,修正后的地震影响系数为现行抗震规范中相应取值的1.45倍,提高了结构设计地震力,防止结构发生连续倒塌。 相似文献
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竖向不规则框架结构连续性倒塌分析 总被引：1，自引：0，他引：1
国内外学者利用非线性静力方法进行结构倒塌分析时,研究对象主要集中在规则的结构形式,而针对大量出现的造型独特的竖向不规则建筑的倒塌研究还相对较少。本文基于拆除构件法,利用SAP2000结构有限元软件,对竖向不规则多层框架结构进行了基于非线性静力Pushdown方法的抗连续性倒塌研究。分别研究了拆除同一结构中不同部位构件、不同层数塔楼结构中相同部位构件后剩余结构的承载力变化情况,研究结果表明：拆除竖向承重柱后的剩余结构承载力,随着上部塔楼层数的增加以及拆柱位置的上升而出现不同程度的降低;加强裙楼顶部水平向承重构件,可以使塔楼底部构件破坏后的剩余结构更好地发挥悬链线机制,并防止剩余结构发生无明显征兆的连续性倒塌。 相似文献
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Earthquake-induced building collapse and progressive collapse due to accidental local failure of vertical components are the two most common failure modes of reinforced concrete (RC) frame structures. Conventional design methods usually focus on the design requirements of a specific hazard but neglect the interactions between different designs. For example, the progressive collapse design of an RC frame often yields increased reinforcement and flexural strength of the beams. As a result, the seismic design principle of “strong-column-weak-beam” may be violated, which may lead to unfavorable failure modes and weaken the seismic performance. To avoid these adverse effects of the progressive collapse design on the seismic resistance of RC frames, a novel structural detailing is proposed in this study. The proposed detailing technique intends to concurrently improve the seismic and progressive collapse performances of an RC frame by changing the layout of the newly added longitudinal reinforcement against progressive collapse without introducing any additional reinforcement. A six-story RC frame is used as the prototype building for this investigation. Both cyclic and progressive collapse tests are conducted to validate the performance of the proposed structural detailing. Based on the experimental results, detailed finite element (FE) models of the RC frame with different reinforcement layouts are established. The seismic and progressive collapse resistances of different models are compared based on the incremental dynamic analysis (IDA) and nonlinear dynamic alternate path (AP) methods, respectively. The results indicate that the proposed structural detailing can effectively resolve the conflict between the seismic and progressive collapse designs. 相似文献
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Modelling of R/C members accounting for shear failure localisation: Finite element model and verification 
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下载免费PDF全文 Reinforced concrete (R/C) frame buildings designed according to older seismic codes represent a large part of the existing building stock worldwide. Their structural elements are often vulnerable to shear or flexure‐shear failure, which can eventually lead to loss of axial load resistance of vertical elements and initiate vertical progressive collapse of a building. In this study, a computationally efficient member‐type finite element model for the hysteretic response of shear critical R/C frame elements up to the onset of axial failure is presented; it accounts for shear‐flexure interaction and considers, for the first time, the localisation of shear strains, after the onset of shear failure, in a critical length defined by the diagonal failure plane. Its predictive capabilities are verified against experimental results of column and frame specimens and are shown to be accurate not only in terms of total response, but also with regard to individual deformation components. The accuracy, versatility, and simplicity of this finite element model make it a valuable tool in seismic analysis of complex R/C buildings with shear deficient structural elements. 相似文献
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Near‐collapse response of existing RC building under severe pulse‐type ground motion using hybrid simulation 下载免费PDF全文
下载免费PDF全文 Column shear‐axial failure is a complex response, which lends itself to physical experimentation. Reinforced concrete structures built prior to the mid‐1970s are particularly susceptible to such failure. Shear‐axial column failure has been examined and studied at the element level, but current rehabilitation practice equates such a column failure with structural collapse, neglecting the collapse resistance of the full structural system following column failure. This system‐level response can prevent a column failure from leading to progressive collapse of the entire structure. In this study, a hybrid simulation was conducted on a representative pre‐1970s reinforced concrete frame structure under severe seismic ground motion, in which three full‐scale reinforced concrete columns were tested at the University of Illinois at Urbana Champaign. The analytical portion of the model was represented in the computer program OpenSees. Failure occurred in multiple physical specimens as a result of the ground motion, and the hybrid nature of the test allowed for observation of the system‐level response of the tested columns and the remaining structural system. The behavior of the system accounting for multiple column shear‐axial failure is discussed and characterized. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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在地震作用下钢筋混凝土建筑结构出现破坏倒塌为地震灾害中的关键,有效评估建筑结构抗地震破坏倒塌能力是建筑结构设计的前提,也是当前建筑结构提高抗震性能与加固的依据。提出变形指标极值、失效判断标准以及钢筋混凝土建筑结构倒塌极限状态判断标准,据此获取倒塌储备系数、倒塌易损性、结构整体超强系数、结构整体延性系数等评估标准。采用Pushover分析法选择相应地震波。依据梁柱线刚比对建筑结构抗倒塌能力的影响,以及柱端弯矩增加系数对建筑结构抗地震破坏倒塌能力的影响,对建筑结构易损性进行分析。结果表明:等跨建筑结构抗地震破坏倒塌能力更强;建筑结构底层是薄弱层,COF值越高,结构越容易倒塌。 相似文献
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A framed tube, consisting of closely spaced columns connected by deep spandrel beams, is designed in reinforced concrete for building code loads. The members of the frame are proportioned using strength concepts. A planar model of the tube is developed and its behaviour is compared to that of the three-dimensional structure. The planar model is then used to evaluate the inelastic behaviour of the framed tube when subjected to strong ground motion. The effects of the finite element discretization and the ground motion characteristics are investigated. Results show that ductility requirements of the spandrel beams are minimum at the top and maximum at the bottom of the tube. Ductility requirements in the columns are well controlled and are within acceptable limits. Participation of the higher modes of vibration is significant and requires increasing damping. It also is shown that the increased stiffness due to finite member sizes at a joint cannot be neglected. 相似文献
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目前,地震及爆炸荷载下的结构连续倒塌问题已成为土木工程领域研究的热点。本文首先简要介绍了国内外有关连续倒塌问题的研究现状和规范制定情况,然后基于OpenSees模拟平台,对一钢筋混凝土框架结构进行了拆除柱构件的动力分析。计算结果表明:拆除边柱比拆除内柱对结构的倒塌危险性要大,楼板对拆除构件后结构的动力反应有一定的减小作用。依据美国公共事务管理局(GSA)的倒塌规范,采用静力非线性分析和竖向增量动力分析对结构抗连续倒塌能力进行了研究。分析结果表明:楼板在一定程度上可提高结构抗连续倒塌能力;动力放大系数(DAF)随结构进入塑性而逐渐增大;由静力非线性分析曲线得到的结构抗连续倒塌能力曲线与竖向增量动力分析曲线吻合较好。 相似文献
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An efficient component model has been developed that captures strength and stiffness deterioration of steel hollow structural section (HSS) columns. The proposed model consists of two fiber-based segments at a member's ends along with an elastic segment in between. The fibers exhibit nonlinear uniaxial stress–strain behavior, which is explicitly defined by uniaxial monotonic tensile and cyclic round coupon tests. The postbuckling behavior of an HSS column is traced through a proposed uniaxial effective stress–strain constitutive formulation, which includes a softening branch in compression and an energy-based deterioration rule to trace the influence of cyclic deterioration in the inelastic cyclic straining. These may be inferred by uniaxial stub-column tests. The component model captures the coupling between the column axial force and flexural demands. Consistent model parameters for a number of steel materials used in the steel construction in North America and Japan are proposed along with the associated model calibration process. The efficiency of the proposed model in predicting the hysteretic behavior of HSS columns is demonstrated by comparisons with physical steel column tests subjected to various loading histories, including representative ones of ratcheting prior to earthquake-induced collapse. The proposed model is implemented in an open-source finite element software for nonlinear response history analysis of frame structures. The effectiveness of the proposed model in simulating dynamic instability of steel frame buildings is demonstrated through nonlinear response simulations of a four-story steel frame building, which was tested at full-scale through collapse. Limitations as well as suggestions for future work are discussed. 相似文献