复杂高层钢-混凝土结构地震损伤时变特性研究

Research on Time-dependent Seismic Damage Characteristic of Complex High-rise Steel-concrete Composite Structure

复杂高层结构抗震性能化设计尚未考虑服役期内材料性能劣化所引起的损伤的非线性演化过程.本文面向复杂高层钢-混凝土组合结构,考虑不同服役期内混凝土材料性能劣化所引起的局部构件和结构整体力学性能的变化,建立了组合结构地震损伤时变分析模型.针对结构刚度、阻尼等参数在服役期内具备"变量"的特征,同时在遭遇地震时又具有"常量"的特点,提出将此类参数作为"拟变量"处理,分析了结构的弹塑性动力响应;依据动力响应结果,分别基于层间位移的整体法和基于构件损伤的加权组合法建立了结构损伤时变模型,研究了复杂高层钢-混组合结构的抗震性能.结果表明:服役期内结构性能呈现显著的时变特性,多遇地震下结构损伤可能超出限值;刚度变化引起抗侧向作用力和地震作用传导能力的共同变化.对比分析了基于地震损伤时变模型和常规模型的结构参数设计值的差异,发现材料时变特性对结构抗震设计和评估的精确性具有较大影响.

Nonlinearly evolutionary process of damage due to material degradation is not considered in the seismic performance design of complex high-rise structure.Aiming at complex high-rise steel-concrete composite structure, the time-dependent characteristic of local component and whole structure induced by key parameters of concrete material was considered in this paper. Combining the time-dependent model of seismic damage with dynamic elastic-plastic time history analysis method, damage time-dependent characteristic of high-rise steel-concrete composite structure was studied.Because key parameters such as stiffness and damping not only have the ＂variable＂ character in service periods, but also have the ＂constant＂ character under seismic loads, the method regarding the key parameters as ＂quasi-variables＂ was proposed. Dynamic elastic-plastic time history analysis was used to obtain the dynamic response of the structure. Both the integral method＇based on interlayer displacement and the weighted combination method based on component＇ damage were used to research on the time-dependent characteristic of the composite structure.The result shows that the structure in service period has significantly time-dependent characteristic. Time-dependent damage might exceed the corresponding threshold value under frequent earthquakes. The change of stiffness may lead to the change of the lateral force and the transmission capacity of earthquake action. Compareing the time-dependent damage in service period with design value without counting the time-dependent characteristics, it can be found that time-dependent characteristics of material have great influence on the accuracy of the seismic design and evaluation of the structure.