【作者】 付国；

【导师】 刘伯权；

【作者基本信息】 长安大学 ， 结构工程， 2014， 博士

【摘要】 任何情况下人的生命安全都是第一位的。强震作用下建筑物的倒塌造成的人员伤亡将引发一系列较财产损失更严重、更复杂的社会问题和经济问题。近年来国内外的数次震害表明即使严格执行抗震设计的建筑物也可能发生不同程度的倒塌破坏，大震不倒抗震设防目标未充分实现的根本原因在于未对结构倒塌破坏机理进行深入研究，缺乏准确的倒塌破坏临界状态定义和合理的倒塌破坏准则。本文重点研究了钢筋混凝土框架结构的倒塌破坏特点和破坏机理，建立了结构倒塌破坏分析模型、临界状态、破坏准则，主要涉及以下工作：深入分析总结了结构倒塌破坏研究方法，已有倒塌破坏准则本质上是构件设计的延伸，融入结构思想的倒塌研究考虑了构件、子结构、结构破坏的不确定性。薄弱区域的塑性变形集中是倒塌发生的根本原因，框架结构塑性变形集中区域就是柱铰大量充分发育的区域，此时结构内力重分布能力逐步下降，形成柱铰破坏机制。创造性的提出了结构域倒塌破坏分析模型和塑性铰密度倒塌破坏准则，在构件、子结构、整体结构三个层面上对倒塌研究进行了思考和探索，建立了可行的倒塌研究分析思路和方法。分析了结构倒塌破坏特性并提出了结构倒塌破坏分析模型，定义倒塌临界状态为地震作用下发生不同程度破坏后结构的极限性能，以倒塌区间代替单一倒塌临界值。根据同一层内受损构件的位置、破坏程度和数量等指标，将引起层倒塌的、破坏程度相近的同类型构件组合定义为倒塌关键区域，建立了域倒塌破坏分析模型。域失效是倒塌破坏发生的根本原因，真实反映了结构整体性能的退化规律和特点，适用于不同类型的倒塌研究。对框架结构的倒塌破坏机制和内力重分布特性进行深入分析，建议了基于柱铰的倒塌破坏准则。选取柱端塑性铰发育为倒塌分析变量，根据塑性铰发育程度、出现位置和数量等参数定义了塑性铰密度倒塌破坏准则。塑性铰密度破坏准则考虑了塑性铰发育与结构整体性能退化之间的相互关系。从构件损伤、子结构破坏和结构倒塌破坏三个层面上对倒塌破坏机理进行了解释和说明。薄弱层内一定量的柱铰充分发育后，结构的内力重分布能力丧失，子结构转化为可变机构，标志着倒塌的开始。试验研究和有限元分析表明域模型和塑性铰密度破坏准则较准确的解释和定义了结构倒塌临界状态、揭示了倒塌破坏机理。结构倒塌是由一定量的框架柱塑性变形集中引起的，柱端塑性变形是倒塌破坏研究的关键内容，对框架柱的损伤和塑性变形程度量化进行了研究：考虑滞回耗能与构件损伤的相互关系提出了有效耗能理论，建立了考虑延性和有效耗能比例的改进双参数破坏准则；研究了柱的截面破坏特性，在理论分析基础上通过数据回归得出了框架柱的极限曲率计算公式，建立了塑性铰发育量化方法。根据三榀平面框架的拟静力试验，建立了OpenSees的纤维单元模型，进行了框架结构的反复加载试验验证，完成了基于塑性铰密度破坏准则的平面框架结构倒塌计算分析，选取倒塌破坏区间(0.6,1.0)能够准确的定义倒塌破坏极限，倒塌破坏指数较好的反映了结构的整体性能退化规律。选取114条地震波进行了框架结构的时程分析，根据倒塌破坏指数大小从中选取了10条地震动作为后续参数分析的地震动数据库。完成了不同层数、层高、跨度、轴压比的倒塌破坏计算分析，计算表明随着层数、层高、跨度、轴压比的增加倒塌破坏总体呈现加剧的趋势，基于域模型的塑性铰密度准则能够较好的定义结构倒塌破坏，地震动随机性对结构倒塌破坏的影响不容忽视。更多还原

【Abstract】 Life safety is always the first one in any case. Under strong earthquakes, the collapse ofbuildings caused heavy casualties and property losses, especially casualties would trigger a seriesof more complex and serious social and economic problems than the property damage. In recentyears, several damage at home and abroad have shown that the strict implementation of theseismic design of buildings may also occur in varying degrees of collapse damage, thefundamental reason of the fortification objective―no collapsing with strong earthquake‖not toachieve lies in the lack of further study on failure mechanism of structural collapse, the precisedefinition of the collapse damage critical state and the reasonable establishment of quantitativecriteria of collapse. Here the failure characteristics and mechanism of reinforced concrete framestructural collapse are focused on research, besides, analysis model, the critical state and failurecriteria of collapse damage are established. The major works are summarized as follows:The existing research methods of structural collapse damage are deeply analyzed andsummarized. Existing design methods is essentially the extension of member design, while theimproved research of structural collapse into the structural thought contain the uncertainty ofmember, sub-structure and structural damage. The concentration of plastic deformation in weakareas is the fundamental reason for the collapse occurred. The plastic deformation concentratedarea of frame structure is a large number of fully developed hinge pillar area, at this point, theredistribution capacity of structural internal force is gradually decreased to form a hinge pillarfailure mechanism. Domain-failure damage model and plastic-hinge density failure criterion areproposed. It is reflection and exploration for collapse research from the three levels of components,sub-structure and the overall structure, then, the analytical ideas and methods of a feasible collapseresearch are established.The characteristics of collapse damage was analyzed, the critical state of collapse wasdefined as limit performance of incomplete structure after different degrees of injury occurredunder the action of earthquake. According to some indicators of the damaged components withinthe same layer, such as location, the degree of damage and quantity, component composition of the same type of causing the collapse of the layer and the similar extent of damage was defined as thekey areas of collapse. Analysis model of domain collapse damage was established. Domain failurewas the primary cause of collapse damage occurred. It truly reflected the degradationcharacteristics of the overall performance and applies to the different types of collapse.By analyzing the mechanism of collapse of the framework structure and the characteristics ofthe internal force redistribution, on the basis of domain model studies, the development of columnplastic hinge was selected as collapse analysis variables. According to the degree of developmentof plastic hinges, the location of plastic hinge appears, the number of column plastic hinges andother parameters, the collapse failure criterion of plastic hinges density was defined. Therelationship between the column injury and overall performance degradation of the structure wasconsidered in the failure criterion. Collapse was demonstrated and explained from three levels,such as component damage, sub-structural damage and structural collapse damage. After a certainamount of columns hinges in the weak story fully developed, the capability of redistribution ofinternal forces of the structure was lost, then substructure into variable mechanism marked thebeginning of the collapse, the critical state of collapse was accurately defined, failure mechanismwas interpreted and quantitative analysis was achieved by domain model and plastic hingesdensity failure criterion.The collapsed damage is due to the concentration of plastic deformation in the column-end,the damage and quantify of the degree of plastic deformation of frame column were studied.Effective energy theories have been proposed by considering the relationships between hystereticenergy and component damage, improved two-parameter failure criterion was established byconsidering ductility and the ratio of energy efficient, the failure characteristics of section of thecolumn were studied, on the basis of the theoretical analysis, the calculation formula of ultimatecurvature of frame column was derived by data regression, the quantization method of thedevelopment of plastic hinges was established.According to the pseudo-static test of three specimens of plane frame, fiber element modelbased on OpenSees was established, experimental verification of cyclic loading tests of framestructure were carried out, the calculation and analysis of plane frame structure collapse wascompleted based on plastic-hinge density failure criterion, the selected collapse interval (0.6,1.0) can accurately express the limits of collapse, Collapse damage index can better reflect thedeterioration of the whole performance of the structure.The framework structure’s time historyanalysis was conducted by selecting114seismic waves. According to the size of collapse damageindex,10ground motions were selected as a ground motion database for follow-parametricanalysis. The calculation and analysis of collapse damage were completed on different layers,different story height, different span length and different axial compression ratio. The resultsshowed that as the increase of layer numbers, story height, span length and axial compression ratio,collapse damage as a whole presents an exacerbated trend. Structural collapse was well defined byplastic-hinge density failure criterion based on domain-failure damage model, the impact ofground motion randomness to structural collapse damage cannot be ignored.更多还原