冲击作用下钢筋混凝土框架抗连续倒塌试验与数值模拟研究

发布时间：2018-06-15 17:45

本文选题：B冲击荷载 + 动力性能分析　；参考：《湖南大学》2015年硕士论文

【摘要】：近年来,偶然荷载作用下结构的抗连续倒塌研究已成为国内外研究热点,然而现有的研究多集中在由于楼层关键构件的突然失效而引起的连续倒塌,对由于上部坍塌楼层对下部楼层的冲击作用引起的连续倒塌研究很少,随着高层以及超高层建筑的广泛应用,对于冲击荷载作用下钢筋混凝土框架的抗连续倒塌研究显得越来越重要。(1)本文采用锤击法对一榀单层两跨钢筋混凝土平面框架结构分别在空载、均布线荷载工况下进行了动力试验研究,对锤击荷载作用下钢筋混凝土框架的受力状态以及响应特性进行了分析和讨论,分析结果表明:框架梁由弹性受力阶段进入拱效应受力阶段后,其刚度有所提高。试验框架所受的锤击力幅值大于结构的静力承载能力,而结构没有倒塌且仅处于弹塑性受力阶段,主要原因是锤击力幅值主要由惯性力平衡,且力锤输入结构的能量有限不足以使结构发生倒塌。(2)本文采用自制冲击加载装置完成了一榀单层两跨钢筋混凝土平面框架的小当量冲击试验。研究了试验框架在冲击荷载作用下的动力响应特性、内力分布规律、钢筋的应变率效应以及冲击质量和冲击高度对框架梁动力响应特性的影响,并对框架梁在冲击荷载作用下的动力荷载放大系数以及应变率效应对钢筋强度的影响程度进行了探讨和分析。试验结果表明:应变率效应对钢筋强度提高程度较低,屈服强度的最大放大系数为1.09-1.11之间,极限强度的最大放大系数为1.06-1.07之间。冲击荷载作用下,框架梁的动荷系数随着冲击高度的增加而增加,随着结构损伤程度和冲击质量的增加而下降。(3)本文采用有限元软件LS-DYNA对两个一层、四个三层钢筋混凝土框架在冲击荷载作用下的倒塌过程进行了模拟,研究了冲击荷载作用下钢筋混凝土框架的受力性能,对各框架的破坏状态进行了对比分析,并对冲击荷载作用下框架的倒塌过程以及位移、内力等响应特性进行了分析。分析结果表明:冲击荷载作用下,钢筋混凝土框架的受力过程均经历了明显的拱效应和悬索效应阶段,且冲击荷载作用下钢筋混凝土梁的最大内力相对静力承载能力有所提高。通过比较四个三层框架的抗连续倒塌能力,可知对一层框架梁进行加强可以充分发挥材料的性能又不影响结构抗连续倒塌能力。(4)采用有限元软件ATENA对两个一层、四个三层钢筋混凝土框架进行了静力性能分析。计算结果表明ATENA软件可以计算结构从弹性阶段到悬索效应阶段的全受力过程,框架在冲击荷载以及静载作用下破坏状态类似。通过比较各框架的承载能力可知,在塑性受力阶段,各框架的承载能力存在明显的区别,在悬索效应受力阶段,各框架的承载能力差别相对较小。基于静载承载能力以及冲击荷载作用下的承载能力,可知框架梁的荷载放大系数在1.22到1.82之间。(5)基于ATENA分析得到的荷载-位移曲线,采用非线性时程分析方法对框架梁在小荷载冲击作用下的动力响应进行了计算和分析,计算结果与实测结果吻合较好。采用能量方法与非线性时程分析方法对六榀框架的抗倒塌能力进行了计算,计算结果表明,采用能量方法可以偏于保守的预估结构的抗连续倒塌能力以指导设计。
[Abstract]:In recent years, the study of continuous collapse resistance of structures under accidental loading has become a hot spot at home and abroad. However, the existing research is mainly focused on the continuous collapse caused by the sudden failure of the key members of the floor. The extensive application of super high rise buildings is becoming more and more important for the study of the continuous collapse of reinforced concrete frames under impact loads. (1) this paper adopts the hammering method to study the dynamic test of a single layer and two span reinforced concrete frame structure under load condition, respectively under load condition. The stress state and response characteristics of the reinforced concrete frame are analyzed and discussed. The results show that the stiffness of the frame beam is increased after the elastic stress stage enters the arch effect stage. The amplitude of the hammer force is larger than the static bearing capacity of the structure, and the structure is not collapsed and only in the elastoplastic stress order. The main reason is that the amplitude of the hammer force is mainly balanced by the inertia force, and the energy of the input structure of the force hammer is not enough to cause the collapse of the structure. (2) a small equivalent impact test on a single layer and two span reinforced concrete plane frame was completed by the self-made impact loading device. The dynamic force of the test frame under the impact load was studied. The response characteristics, the internal force distribution, the strain rate effect of the steel bar and the impact quality and the impact height on the dynamic response characteristics of the frame beam, and the influence degree of the dynamic load amplification factor and the strain rate effect on the strength of the steel bar under the impact load are discussed and analyzed. The test results show that the strain rate is the strain rate. The effect on reinforcing bar strength is lower, the maximum magnifying coefficient of yield strength is 1.09-1.11, the maximum magnification coefficient of limit strength is 1.06-1.07. Under impact load, the dynamic load coefficient of frame beam increases with the increase of impact height, and decreases with the increase of structural damage degree and impact quality. (3) this paper is adopted in this paper. The finite element software LS-DYNA is used to simulate the collapse process of two layers and four three storey reinforced concrete frames under the impact load. The stress performance of the reinforced concrete frame under the impact load is studied. The failure state of each frame is compared and analyzed, and the collapse process of the frame under the impact load is also analyzed. The response characteristics, such as displacement and internal force, are analyzed. The results show that under the impact load, the stress process of the reinforced concrete frame has experienced the obvious arch effect and the suspension effect stage, and the maximum internal force of the reinforced concrete beam under the impact load is improved. By comparing the four three layers frame, the reinforced concrete beams are compared. The ability to resist continuous collapse shows that the strengthening of a frame beam can give full play to the performance of the material and does not affect the structure resistance to continuous collapse. (4) the finite element software ATENA is used to analyze the static performance of the two layers and four three layers reinforced concrete frames. The calculation results show that the ATENA software can calculate the structure from the elastic order. The failure state of the frame under the impact load and the static load is similar. By comparing the bearing capacity of each frame, the bearing capacity of each frame is distinctly different in the stage of plastic stress, and the bearing capacity of each frame is relatively small in the stage of the suspension effect. Based on static load, the bearing capacity of the frame is relatively small. Bearing capacity and bearing capacity under the impact load, it is known that the load magnification coefficient of frame beam is between 1.22 and 1.82. (5) the load displacement curve based on ATENA analysis, and the nonlinear time history analysis method is used to calculate and analyze the dynamic response of frame beam under small load impact. The energy method and nonlinear time history analysis method are used to calculate the anti collapse ability of the six frames. The calculation results show that the energy method can be partial to the conservative collapsing ability of the predicted structure to guide the design.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375.4;TU312.3

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