【作者】 李昊；

【导师】 周威；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2024， 博士

【摘要】 以预制预应力混凝土双T板拼装形成楼盖,双T板间通过盖板、发卡式等干式连接后成为水平结构体系;结合支承水平楼盖体系所需的预制倒T形梁、预制混凝土柱以及预制内外墙组成的围护结构及抗侧结构,可形成内部大空间装配式结构,特别适用于要求内部空旷的大型公共建筑。干连接双T板拼装形成的装配式结构,以极限侧移、延性性能等表征的整体抗震性能及地震易损性是进行抗震设计的基础。在罕遇地震或极罕遇地震条件下,楼/屋盖双T板的扰动掉落、落碰坍塌、双T板的连接件可能发生的平面内外错动,直接决定着整体结构的抗震能力。聚焦干连接双T板装配式结构横隔板效应和结构抗震能力,按结构震致横隔板效应、抗倒塌能力、易损性和震致双T板落碰冲击四个方面展开工作:(1)提出了干连接双T板装配式结构横隔板效应分析方法。分析了多种板面连接及板端连接的静力及滞回性能,对比了连接构件的荷载-位移关系、刚度退化、位移延性等,建立了连接的恢复力模型。分析了不同连接件刚度或楼层数对干连接装配式结构动力响应的影响,分析发现,装配式节点增加了高振型地震响应参与,需增加振型数进行结构抗震设计计算。基于等效梁模型理论建立了干连接双T板楼盖体系平面内刚度计算方法,并基于弹塑性时程分析提出了干连接双T板装配式结构横隔板效应判定准则,分析发现,采用柔性连接的结构其横隔板效应极差,水平地震作用无法在平面内进行有效传递。(2)构建了干连接多层次失效楼盖局部坍塌和整体倒塌能力评价方法。选取连接件刚度、楼层数和加载方向等共5个结构特征参数作为变量,建立了102种干连接双T板装配式结构模型,开展了弹塑性静力分析。分析了干连接双T板装配式结构的塑性铰发展历程与地震破坏模式;建立了结构破坏等级与量化指标的对应关系,提出了楼盖局部坍塌的判定准则,统计了所研究的102种结构的楼盖可能发生局部坍塌的位置。以结构抗震性能系数定量表征结构抗侧向倒塌能力,分析了结构超强系数、延性系数、延性折减系数、反应修正系数以及位移放大系数,建立了干连接装配式结构延性与承载力的双重控制分析方法。(3)建立了SPO2IDA算法框架下的地震易损性及抗震能力预测模型,量化地震危险性。引入楼盖局部坍塌性态点,建立了易损性评估方法,发现随连接件刚度的增大,结构达到不同极限状态的超越概率均减小。建立了包含453种不同参数干连接双T板装配式结构抗震性能的样本库,采用五种机器学习回归算法,训练了易损性及抗震能力预测模型,提出了基于机器学习模型的结构参数敏感性分析方法,五种算法均可不同程度上预测结构的抗震能力,遗传算法优化神经网络预测结果相对更稳定。构建了干连接双T板装配式结构地震风险性概率分析法及结构经济损失方法,分析了结构的总损失比曲线与年度期望损失。(4)提出了连接渐近失效后双T板落碰冲击及竖向连续坍塌分析方法。针对震致局部连接失效而导致双T板坍塌,进而造成水平楼盖的竖向连续坍塌问题,研究了从落板与受冲击板接触瞬时到受冲击板完全破坏的短时冲击进程,发展了落碰冲击抗力随机性模型,建立了基于悬链线机制的双T板楼盖体系抗落碰冲击承载力分析方法。发现板-板连接的刚度直接控制着受冲击板的连续坍塌机制,布置高刚度连接件的双T板体系具有协调变形的能力。随着冲击速度的增大,受冲击双T板将发生失稳,从而导致干连接双T板结构竖向连续坍塌。建议了增强板端支承连接构造或双T板延性的防落碰坍塌措施。更多还原

【Abstract】 Precast prestressed flat double-tees are assembled to form floor systems.The enclosure structure and lateral resistant structure are composed of precast inverted T-beams,concrete columns,and inner/outer walls required to support the horizontal floor system,forming integral-assembled structures with large internal space,especially suitable for large-scale public structures that require internal openness.Seismic performance and fragility of dry-connected double-tee precast structures characterized by ultimate lateral displacement and ductility are the basis for seismic design.Under rare or extremely rare earthquake actions,the falling debris,collapse of precast diaphragms,and performance of double-tee connectors directly determine the seismic capacity of structures.Therefore,this thesis takes typical dry connected double-tee precast structure as the main object,focusing on diaphragm effectiveness and structural seismic capacity.Research works were carried out from four aspects:diaphragm effectiveness,collapse,fragility,and impact capacity:(1)An analysis method was proposed for the diaphragm effectiveness of dry connected double-tee precast structures.Monotonic and hysteresis performance of various floor-to-floor connectors and floor-to-wall/beam connectors was analyzed,the load-deformation relationship,stiffness and ductility were obtained,and hysteretic models of connectors were established.An numerical analysis was carried out for a series of precast structures with different type of floor-to-floor connectors and number of stories.The results showed that stiffness of floor-to-floor connectors and number of stories can affect the natural period of the structure,and precast structures with flexible floor-to-floor connectors is regarded as representing precast structures which are largely influenced by higher-order modes under earthquake.Therefore,it is wrong for many structural designers to regard the floor of the large-span precast structure as rigid diaphragm in structural design.A calculation method for in-plane stiffness of precast diaphragms was established based on equivalent beam model theory,and a criterion for determining diaphragm effectiveness of dry connected double-tee precast structures was proposed based on nonlinear time history analysis.The diaphragm acceleration of precast structures with rigid connectors is generally small,while that of structures with flexible connectors is obviously large,which leads to very poor diaphragm effectiveness.(2)An evaluation method for local collapse and overall collapse capacity caused by failure of connectors was constructed.The variation of a set of structural parameters was considered,including shear stiffness and tensile stiffness of connectors,number of stories,and two orthogonal directions of the seismic action,to establish 102 structural models of double-tee precast structures,and nonlinear static analysis was conducted.The development process of plastic hinges and seismic failure modes of double-tee precast structures were investigated,the relationship between the damage grade and quantitative indicators of precast structures were established,criteria for determining local collapse of diaphragms was proposed,and the possible locations of local collapse of double-tees in 102 studied structures were summarized.The seismic performance factors are used to quantify lateral collapse resistant capacity of codified designed structures,the system overstrength factor,the ductility factor,the ductility reduction factor,the response modification coefficient and the deflection amplification factor are all obtained to realize dual control of structural ductility and capacity.(3)A seismic fragility and seismic capacity prediction model was established based on SPO2IDA algorithm framework,and the seismic hazard was quantitatively analyzed.A fragility assessment method was established by considering local collapse of diaphragms as a special failure mode.The results show that the structures with flexible connectors present a higher level of fragility than those with more rigid connectors.A database was established for the seismic performance of 453 double-tee precast structures with different parameters,five predicting models based on machine learning were proposed to evaluate the seismic performance of the structures,and a sensitivity analysis method for structural parameters based on machine learning models was proposed.All five predicting capacity models could provide a reliable capacity measure for the estimation of seismic fragility and structural response,and it is shown that genetic algorithm-based neural networks outperform the other four methods in terms of prediction accuracy.Furthermore,a probability analysis method for seismic risk of double-tee precast structures and a structural economic loss method were constructed,and total loss ratio curves and expected annual loss of the structures were obtained.(4)Dynamic response and failure mechanism analysis of double-tee precast structures under falling double-tee impacts were investigated.The evolution of damage in a large-span double-tee that is impacted by a double-tee that is falling from above due to failure of local connector failure,thus starting a progressive collapse scenario was investigated.This paper aims at investigating the processes occurring during this short duration from the instant of contact between the impacting double-tees until a complete failure of the impacted double-tees is reached,thus gaining insight into the evolution of the damage.Random model research on resistance under falling debris impact was conducted,and impact capacity of precast double-tee can be determined by linear or curved catenary mechanisms.It was found that the stiffness of the floor-to-floor connectors is crucial to the prevention of progressive collapse.The floor system equipped with high-stiffness connectors has the ability to coordinate deformation.With the increase of impact velocity,the impacted double-tees would become unstable and result in progressive collapse of the structure.Suggestions have been made for anti-collapse measures such as strengthening the end support connectors or ductility of double-tees.更多还原