考虑土—结构相互作用的桥梁多尺度建模与分析
发布时间：2018-10-08 19:28
【摘要】：桥梁的上部结构通过基础与地基相连,结构-基础-地基构成了相互依赖的完整体系。在地震作用下,地震波经过土的传播作用于结构体系,地震工程实践表明,考虑土-结构相互作用的桥梁体系地震响应分析是值得做的。但是,由于考虑土-结构相互作用的桥梁体系结构比较大,对其进行模拟分析时,计算时间长、内存需求大、计算效率较小甚至无法实现。为了解决该问题,本文采用多尺度建模方法对该类结构进行建模并对其地震响应进行分析,主要工作和结论如下:(1)本文基于结构多尺度建模理论,在同一结构模型中通过采用精细单元模拟结构的关键(或易损伤)部位,宏观单元模拟其他部分,在此之后不同单元之间进行截面耦合,使不同单元之间的变形协调达到了一致。(2)由于不同单元在进行截面连接时会松弛一部分自由度,使多尺度模型较实际模型整体刚度小,因此本文通过修改宏观单元刚度实现多尺度模型整体刚度的修正,旨在满足工程实际要求;对比地震荷载作用下修正后多尺度模型与精细模型的位移、速度和加速度响应,验证了修正后多尺度模型与工程实际之间的一致性。(3)合理的地震动输入是保证结构地震响应的关键因素,对于考虑土-结构相互作用的整体桥梁体系而言,地震动的输入应该采用地下某一深度的地震波而不是采用基于地表记录的地震波。因此,本文采用Thomson-Haskell传递矩阵法,推导了地震波经过层状土体时的传递函数,根据得到的传递函数和基于地表所记录的地震波时程(EI Centro波和天津波),得到了相应的地下地震波,其正确性也被验证,旨为后续结构的地震响应分析做准备。(4)通过比较分析地下地震动激励下桥梁结构的位移响应、墩底剪力、滞回曲线和耗能能力等特征,探究了土体、纵向配筋率和配箍率等参数对桥梁体系的地震响应影响规律。结果表明:考虑土-结构相互作用后,土体对地震能量有一定的耗散作用,对桥梁的抗震性能需求有所降低,在桥梁抗震设计时应加以考虑;提高纵向配筋率,墩顶最大位移呈减小趋势,墩底最大剪力呈增大趋势,但当继续增大纵向配筋率时,墩底混凝土先于钢筋破坏,出现超筋破坏现象,墩底最大剪力反而下降,因此对桥墩进行配筋时,纵向配筋率不宜过大;增加配箍率,墩顶最大位移变化较小,墩底最大剪力在一定范围内波动,总体来说配箍率对桥梁结构的耗能能力不及纵向配筋率的大,但不容忽略。
[Abstract]:The superstructure of the bridge is connected to the foundation through the foundation, and the structure-foundation-foundation constitutes a complete interdependent system. Seismic wave propagating through soil acts on structural system under earthquake action. Seismic engineering practice shows that the seismic response analysis of bridge system considering soil-structure interaction is worth doing. However, due to the large structure of bridge considering soil-structure interaction, the calculation time is long, the memory requirement is large, and the computational efficiency is low or even impossible. In order to solve this problem, the multi-scale modeling method is used to model this kind of structure and its seismic response is analyzed. The main work and conclusions are as follows: (1) based on the theory of multi-scale structural modeling, In the same structural model, fine elements are used to simulate the key (or vulnerable) parts of the structure, and macro elements are used to simulate the other parts, after which the cross-section coupling is carried out between the different elements. The deformation coordination among different elements is consistent. (2) because different elements relax some degrees of freedom in cross-section connection, the multi-scale model has less overall stiffness than the actual model. In this paper, the overall stiffness of the multi-scale model is modified by modifying the macro-element stiffness to meet the practical engineering requirements, and the displacement, velocity and acceleration responses of the modified multi-scale model and the refined model under earthquake load are compared. The consistency between the modified multi-scale model and the engineering practice is verified. (3) reasonable earthquake input is the key factor to ensure the seismic response of the structure, and for the whole bridge system, the soil-structure interaction is considered. Seismic waves at a certain depth of the ground should be used instead of seismic waves based on surface records. Therefore, using the Thomson-Haskell transfer matrix method, the transfer function of seismic wave passing through layered soil is derived. According to the obtained transfer function and the time-history (EI Centro wave and Tianjin wave recorded on the ground, the corresponding underground seismic waves are obtained. Its correctness has also been verified, which is intended to prepare for the seismic response analysis of subsequent structures. (4) by comparing and analyzing the displacement response, pier bottom shear, hysteretic curve and energy dissipation capacity of the bridge structure under ground motion excitation, the soil mass is explored. The effect of longitudinal reinforcement ratio and hoop ratio on seismic response of bridge system is studied. The results show that considering the soil-structure interaction, the soil has a certain dissipation of seismic energy, and the demand for seismic performance of the bridge is reduced, which should be taken into account in the seismic design of the bridge, and the longitudinal reinforcement ratio should be increased. The maximum displacement at the top of the pier decreases and the maximum shear at the bottom of the pier increases. However, when the ratio of longitudinal reinforcement is increased, the concrete at the bottom of the pier is destroyed before the reinforcement, and the failure of the superreinforcement occurs, but the maximum shear at the bottom of the pier decreases. Therefore, the longitudinal reinforcement ratio should not be too large when the pier is reinforced, the maximum displacement of the pier top changes little with increasing the hoop ratio, and the maximum shear force at the bottom of the pier fluctuates in a certain range. Generally speaking, the energy dissipation capacity of bridge structure is less than that of longitudinal reinforcement ratio, but it can not be ignored.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441
本文编号：2257997
[Abstract]:The superstructure of the bridge is connected to the foundation through the foundation, and the structure-foundation-foundation constitutes a complete interdependent system. Seismic wave propagating through soil acts on structural system under earthquake action. Seismic engineering practice shows that the seismic response analysis of bridge system considering soil-structure interaction is worth doing. However, due to the large structure of bridge considering soil-structure interaction, the calculation time is long, the memory requirement is large, and the computational efficiency is low or even impossible. In order to solve this problem, the multi-scale modeling method is used to model this kind of structure and its seismic response is analyzed. The main work and conclusions are as follows: (1) based on the theory of multi-scale structural modeling, In the same structural model, fine elements are used to simulate the key (or vulnerable) parts of the structure, and macro elements are used to simulate the other parts, after which the cross-section coupling is carried out between the different elements. The deformation coordination among different elements is consistent. (2) because different elements relax some degrees of freedom in cross-section connection, the multi-scale model has less overall stiffness than the actual model. In this paper, the overall stiffness of the multi-scale model is modified by modifying the macro-element stiffness to meet the practical engineering requirements, and the displacement, velocity and acceleration responses of the modified multi-scale model and the refined model under earthquake load are compared. The consistency between the modified multi-scale model and the engineering practice is verified. (3) reasonable earthquake input is the key factor to ensure the seismic response of the structure, and for the whole bridge system, the soil-structure interaction is considered. Seismic waves at a certain depth of the ground should be used instead of seismic waves based on surface records. Therefore, using the Thomson-Haskell transfer matrix method, the transfer function of seismic wave passing through layered soil is derived. According to the obtained transfer function and the time-history (EI Centro wave and Tianjin wave recorded on the ground, the corresponding underground seismic waves are obtained. Its correctness has also been verified, which is intended to prepare for the seismic response analysis of subsequent structures. (4) by comparing and analyzing the displacement response, pier bottom shear, hysteretic curve and energy dissipation capacity of the bridge structure under ground motion excitation, the soil mass is explored. The effect of longitudinal reinforcement ratio and hoop ratio on seismic response of bridge system is studied. The results show that considering the soil-structure interaction, the soil has a certain dissipation of seismic energy, and the demand for seismic performance of the bridge is reduced, which should be taken into account in the seismic design of the bridge, and the longitudinal reinforcement ratio should be increased. The maximum displacement at the top of the pier decreases and the maximum shear at the bottom of the pier increases. However, when the ratio of longitudinal reinforcement is increased, the concrete at the bottom of the pier is destroyed before the reinforcement, and the failure of the superreinforcement occurs, but the maximum shear at the bottom of the pier decreases. Therefore, the longitudinal reinforcement ratio should not be too large when the pier is reinforced, the maximum displacement of the pier top changes little with increasing the hoop ratio, and the maximum shear force at the bottom of the pier fluctuates in a certain range. Generally speaking, the energy dissipation capacity of bridge structure is less than that of longitudinal reinforcement ratio, but it can not be ignored.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441
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