【作者】 陈磊；

【导师】 韩军；

【作者基本信息】 重庆大学 ， 土木工程， 2016， 硕士

【摘要】 底部框架-抗震墙砌体房屋广泛存在于我国中小县城及乡镇中,由于底框结构底部大空间导致结构竖向“上刚下柔,头重脚轻”,属于明显竖向不规则结构。在汶川地震的震害统计中,底框结构抗倒塌性能的差异性较大,有的上部砌体房屋层倒塌较严重,有的底部框剪层倒塌较严重,说明以往研究及规范采用的刚度比指标引导破坏模式具有较大不确定性,如何引导底框结构较大概率发生合理破坏模式,提高抗倒塌能力仍然是亟待解决的问题。本文首先严格按照我国规范对8度0.2g区不同刚度比和剪力墙布置形式的底框结构进行算例设计,应用Perform-3D软件对不同刚度比底框结构进行大震下破坏模式的比较,研究较可靠实现结构底层破坏的刚度比;对较大刚度比底框结构进行小震设计中的减震规律研究和不同地震强度下粘滞阻尼器减震效果的分析,最后通过一个工程算例验证本文提出的阻尼器设计方法。通过上述思路,本文主要研究结论如下:(1)对不同刚度比、不同剪力墙布置情况的底部框架-抗震墙砌体结构大震下位移反应和结构损伤进行对比分析,底框结构主要以剪切破坏为主,结构损伤随着刚度比的增大向底部框剪层集中,刚度比大于2.00的底框结构损伤主要集中在结构底层,砌体过渡层仅少数墙单元开裂,较可靠实现了结构底层破坏。(2)对刚度比大于2.00的底框结构通过底层布置粘滞阻尼器进行减震控制,结果表明结构位移减震率随着结构附加阻尼比的增大而增大,但当附加阻尼比增加到10%以后位移减震率增大速率降低,当附加阻尼比增加到20%~25%时,上部砌体层间位移不再减小,为得到较好减震效果又不致破坏向上部砌体层转移,本文建议附加阻尼比取10%到25%之间。(3)通过对刚度比2.00和2.50底框结构减震前后结构损伤分析,未减震底框结构大震下损伤主要集中在结构底层。并随着地震强度的增加破坏进一步向下部集中,通过底层布置粘滞阻尼器的方法有力地吸收了地震能量,减轻底框结构地震中损伤的同时实现了较为均匀合理的损伤机制。(4)本文通过统计回归的方法得到了底框结构采用底层布置粘滞阻尼器的减震方法时结构小震位移减震率和附加阻尼比的数值关系,并通过一个工程算例对该数值关系的应用方法和精确度进行了验证。更多还原

【Abstract】 The masonry buildings with bottom frame-seismic wall is widely distributed in small citys and rural areas in China, however,this kind of buildings also have some inherent defects on account of their large space at bottom. “upper’s weight is heavier than bottom, and upper’s stiffness is stronger than bottom” is one of its characters of this structure, and this kind of masonry structure is belonging to vertical irregular structures.According to the seismic disaster statistics in Wenchuan Earthquake, there was a huge difference in the anti-collapsing ability of the masonry structure with bottom frame-seismic wall.For some structures, their masonry structure at upper stories had collaseped severely, and for some others, their frame-shear wall structure at bottom story suffered serious damage, so this problem illustrated that the structural failure of this special masonry structures was more uncertain. The urgent issues to be studed is how to make sure that this special masonry structure has a reasonable failure mode, and how to improve their anti-collapsing ability.This article designs different analysis examples of masonry structure with bottom frame-shear wall lacated in 8 degree seismic region, and models the finite element models by Perform-3D. This study focuses on the failure law of the masonry structure with different lateral stiffness ratio, the structure damping law in this kind of masonry structure cuased by various additional damping ratio and the structure damping effect changing with seism intensity, and attests the accuracy of the damping rule through an engineering case.According to the ideas mentioned above, the study results are listed as follows:(1)Based on the comparison of elements damage for different structures,the damage of the masonry structure with bottom frame-seismic wall is based more on shear failure and the structure damage drives dowm closer to the bottom. When the lateral stiffness ratio of the masonry is larger than 2.00, the structure demage mainly concentrates on the first story and some masonry elements in the second story.(2)For the damping structures whose lateral stiffness ratio is larger than 2.00, the structure displacements` decrease rate increases with the structure additional damping ratio. When the structure additional damping ratio is larger than 10%, the increase velocity of structure displacements` decrease rate becomes slow than before, and when the additional damping ratio is about 20%~25%, the upper masonry stories` drift doesn`t decrease no longer, by reason of such phenomenon, this article suggests that the structure additional damping ratio could be selected from 10% to 25% in damping design.(3)Through the structure damage analysis of masonry structure with bottom frameseismic wall with different lateral stiffness ratio, the structure damage under rare seism is mainly occurred in bottom of the structure, and the damage is more severe as seismic intensity increasing. The vicious dampers furnished in the bottom could dispate seismic energy effectively and reduce the damage degree of structure under earthquake, then the reasonable failuer mechanism is realized by this method.(4)The numerical relationship of additional damping ratio and the story displacements decrease rate of masonry structure with vicious damper is got by statistical regression method.And the application method and accuracy of the numerical relationship are verified by an engineering example.更多还原