考虑土—结构相互作用的钢筋混凝土框架结构地震倒塌破坏仿真分析

发布时间：2018-01-04 02:44

本文关键词：考虑土—结构相互作用的钢筋混凝土框架结构地震倒塌破坏仿真分析　出处：《辽宁工程技术大学》2013年博士论文　论文类型：学位论文

【摘要】：钢筋混凝土框架结构的抗震研究大多采用刚性地基假定，没有充分考虑土层对地震波的过滤和放大效应，同时对上部结构的地震反应分析主要集中在弹塑性变形阶段，真正实现对结构发生破坏以后的研究较少，因此进行考虑土-结构相互作用的钢筋混凝土框架结构倒塌破坏分析和研究具有一定的重要性和实际意义。本文通过对大量相关文献的概括总结，评述了国内外对钢筋混凝土框架结构倒塌研究的现状与发展水平，对结构地震反应分析的数值方法进行归纳总结，基于结构抗震理论确定了动力相互作用体系的分析模型。在研究土体材料和钢筋混凝土材料本构模型的基础上，确定适合土-结构动力相互作用体系地震倒塌分析的材料本构模型，特别是在钢筋混凝土材料模型中引入损伤破坏限值，利用LS-DYNA软件中的Mat_Concrete_Damage材料模型及Erosion算法，以综合考虑混凝土材料的损伤软化、应变率效应、断裂失效等多种特性，模拟钢筋混凝土材料在地震作用下的破坏情况。通过阅读大量文献，确定出适合于倒塌破坏研究的各种材料模型参数。建立土-结构动力相互作用体系的有限元分析方案。通过合理的选取单元，输入地震动参数及考虑重力等因素的影响，建立了刚性地基及考虑土-结构动力相互作用的钢筋混凝土框架结构三维动力有限元分析模型。利用仿真程序模拟得到的裂缝分布及破坏过程与振动台试验的结果十分吻合，证明用LS-DYNA软件对钢筋混凝土框架结构进行倒塌破坏研究是可行的。通过对刚性地基条件与考虑土-结构相互作用两种情况下框架结构从变形、开裂直至最终倒塌的全过程进行对比分析，得出如下主要结论：（1）刚性地基条件下五层、十层、十五层框架结构的各个楼层加速度峰值在不同刚度条件下沿高度的变化趋势大致相同。顶层加速度峰值随结构刚度的增大而增大，结构的层数越多，顶层加速度峰值相对地面的放大系数越大；（2）刚性地基条件下结构首个破坏点出现的时间随刚度的增大有所延迟。在相同刚度条件下，，层数越多结构破坏越快。五层框架结构的初始破坏点均出现在底层边框架的梁底柱边，十层和十五层框架结构的首个破坏点则出现在结构的上部楼层，这主要是由于结构高振型的影响；（3）土-结构动力相互作用体系的自振频率低于刚性地基时结构的自振频率，且硬土地基时体系的自振频率高于软土地基。相对于刚性地基条件，水平加速度峰值沿楼层的变化更加均匀，加速度峰值在大多数楼层有所折减，但在十层和十五层框架结构中个别楼层也出现了折减系数大于1的情况，因而刚性地基假定下结构的抗震设计并不一定安全；（4）土-结构相互作用体系相比刚性地基出现破坏点的时间有所延迟，同时硬土地基条件下的多数结构破坏点出现的时间早于软土地基，说明软土地基时相互作用的效果比较明显。上部结构的初始破坏位置均出现在框架底层的梁底柱边，与刚性地基的情况不完全一致。裂缝情况与刚性地基时相比发展的要少一些，同时体系在输入地震波后，发生了整体沉降的现象，在软土地基条件下沉降更为严重；（5）在地震作用下所有模型结构的各层梁柱交替发生破坏，属于混合倒塌机制。下部楼层破坏较为严重，这主要是由于下部结构承受了相对较大的重力荷载。同时随着刚度的增大，结构底部的破坏范围向上层逐渐扩大。这是因为强震作用下刚度较小的结构下部楼层发生破坏的时刻较早，而结构下部的破坏消耗了一部分地震能，减缓了地震对上部结构的作用。
[Abstract]:The seismic responses of reinforced concrete frame structures are mostly assumed by rigid foundation , and the filtering and amplification effects of the soil layer on seismic waves are not fully taken into consideration . At the same time , the seismic response analysis of the superstructure is mainly concentrated in the elastic - plastic deformation stage , so that the research on the failure of the structure is less . Therefore , the analysis and research of the collapse failure of the reinforced concrete frame structure considering the soil - structure interaction are of great importance and practical significance . In this paper , the present situation and development level of the research on the collapse of reinforced concrete frame structures are summarized in this paper , and the numerical methods of structural seismic response analysis are summarized . Based on the structural seismic theory , the constitutive model of the dynamic interaction system is determined . Based on the research of the constitutive model of the soil material and reinforced concrete material , the damage condition of the reinforced concrete material under earthquake is determined by using the Mat _ Concrete _ Damage material model and the algorithm of the LS - DYNA software . The finite element analysis method of soil - structure dynamic interaction system is established . The three - dimensional dynamic finite element analysis model of reinforced concrete frame structure with rigid foundation and considering soil - structure dynamic interaction is established through reasonable selection unit , input ground motion parameters and considering the influence of gravity and other factors . ( 1 ) The peak acceleration peaks of five , ten and fifteen frame structures under rigid foundation condition are about the same in height under different stiffness conditions . The peak acceleration peak increases with the increase of structural rigidity , and the more layers the structure has , the greater the amplification factor of the peak acceleration peak relative to the ground ; ( 2 ) The time of the first failure point of the structure under the rigid foundation condition is delayed with the increase of rigidity . Under the same stiffness condition , the more the structural damage is . The initial failure point of the five - story frame structure appears on the bottom pillar side of the bottom side frame , and the first failure point of the ten - layer and fifteen - layer frame structure appears on the upper floor of the structure , which is mainly due to the influence of the high - mode shape of the structure ; ( 3 ) The self - oscillation frequency of the soil - structure dynamic interaction system is lower than that of the rigid foundation , and the self - vibration frequency of the system is higher than that of the soft soil foundation . Compared with the rigid foundation condition , the peak of the horizontal acceleration is more uniform along the change of the floor , and the acceleration peak is reduced in most floors , but the seismic design of the rigid foundation assumes that the anti - seismic design of the lower structure is not necessarily safe ; ( 4 ) The time of the soil - structure interaction system is delayed compared with that of the rigid foundation , and the time of most structural damage points under the condition of hard soil foundation is earlier than that of the soft soil foundation , so that the interaction effect of the soft soil foundation is obvious . The initial failure position of the upper structure is not completely consistent with the condition of the rigid foundation . ( 5 ) The failure of each layer beam column of all model structures under the action of earthquake belongs to a mixed collapse mechanism .

【学位授予单位】：辽宁工程技术大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU375.4;TU311.3

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