空间网壳结构损伤评价及加固方法研究

发布时间：2018-03-30 10:38

本文选题：BRB　切入点：受损单层网壳结构　出处：《兰州理工大学》2013年硕士论文

【摘要】：目前,我国已经建成了许多大跨度空间网壳结构,结构在使用过程中,由于各种原因会使既有大跨网壳结构出现不同程度的损伤,而损伤的存在对网壳结构的受力性能是极为不利的,会极大地降低结构的极限承载力和抗震能力,使得原本抗震性能优异的网壳在强震作用下会出现失效、倒塌的可能。我国是地震多发国,大跨网壳结构一般又都属于人流密集的重要公共建筑,使得其抗震性能优劣关系十分重大。因此,对受损大跨网壳结构损伤评价并进行抗震加固修复后,能否继续正常工作并且具有良好的抗震能力,是一个十分有必要去解决的问题,但是关于这方面的研究目前尚不成熟。 BRB(约束屈曲支撑)是目前拥有广泛应用前景的耗能减震构件,施工安装方便、经济、设计灵活而且不影响建筑物的美观,使其不仅成为新建结构抗震设计的较佳选择,也是已建受损结构抗震加固和改造的重要手段。因此本文对约束屈曲支撑在受损大跨网壳结构抗震加固中的应用研究展开了分析。根据剩余模态力理论运用ANSYS有限元软件并结合模态实验测试结果对一受损网壳结构进行基于固有频率变化方法的损伤评价以建立较精确的受损网壳结构数值模型,通过对其进行静力和动力性能分析,提出三种抗震加固方案(方案一,将所有受损杆件进行原杆替换修复；方案二,利用BRB替换所有的受损杆件；方案三,将受损较轻微的杆件替换为原杆,将受损较严重的杆件替换为BRB)。首先对加固前后的模型进行了静力安全性分析,其次选择EL-Centro波,天津波,Taft波罕遇地震记录,按三向输入进行动力时程分析并进行方案对比。然后,从网壳结构形式、BRB屈服强度、尺寸大小以及地震动加速度峰值等方面进行参数分析。最后对雅丹观光塔不规则双层网格结构进行设计分析,找出结构关键杆件,并假设部分杆件受损,对其进行结构剩余承载力评价。通过分析得出以下结论：BRB不仅可以对新建结构进行抗震设计,也可以成为已有受损结构抗震加固和改造的重要手段。通过对三种方案加固后的结构在正常工作状态下的静力安全性分析以及在不同地震波记录作用下的动力响应分析,说明利用BRB进行受损网壳结构的抗震加固在保证结构正常使用静力安全性的前提下,能够很好地改善结构的抗震性能。网壳结构跨度越大、地震动加速度幅值越高,约束屈曲支撑的抗震加固效果越好；BRB屈服强度为80MPa、100MPa,截面尺寸为0.8倍和1.0倍原杆截面时抗震加固效果较好；而且在进行网壳结构分析时不应该忽视下部支撑对上部结构的影响。对一些实际工程可以结合各工况荷载设计分析的结果,假设结构部分杆件出现损伤,通过结构剩余承载力评价的方法找出结构的关键杆件,对后期的施工与使用提供指导。
[Abstract]:At present, many long-span space latticed shell structures have been built in our country. In the process of using, the existing long-span latticed shell structures will be damaged to varying degrees due to various reasons. However, the existence of damage is unfavorable to the mechanical performance of latticed shell structure, which will greatly reduce the ultimate bearing capacity and seismic capacity of the structure, and make the original reticulated shell with excellent seismic performance appear failure under the action of strong earthquake. The possibility of collapse. China is an earthquake-prone country, and the long-span latticed shell structure generally belongs to an important public building with dense flow, which makes its seismic performance very important. It is very necessary to solve the problem of damage evaluation and seismic reinforcement of long-span latticed shell structure, whether it can continue to work normally and have good seismic capacity, but the research on this aspect is not mature at present. BRBs (constrained buckling braces) are energy dissipation shock absorbers with wide application prospects. They are easy to install, economical, flexible in design and do not affect the beauty of buildings, making them not only a better choice for aseismic design of newly built structures, but also a good choice for aseismic design of new structures. It is also an important means for seismic reinforcement and reconstruction of damaged structures. Therefore, the application of constrained buckling braces in seismic reinforcement of long-span latticed shell structures is analyzed in this paper. According to the residual modal force theory, the damage evaluation of a damaged latticed shell structure based on the natural frequency variation method is carried out by using the finite element software ANSYS and the results of the modal experiment to establish a more accurate numerical model of the damaged latticed shell structure. Through the static and dynamic performance analysis, three kinds of seismic reinforcement schemes are put forward: one is to replace all the damaged members with the original rod; the other is to replace all the damaged members with BRB; the third is to replace all the damaged members. The less damaged member is replaced by the original rod, and the severely damaged member is replaced by BRB.Firstly, the static safety analysis of the model before and after reinforcement is carried out, and then the EL-Centro wave, Tianjin wave and Taft Bohan seismic records are selected. The dynamic time history analysis is carried out according to the three-direction input and the scheme is compared. Then, the BRB yield strength is obtained from the reticulated shell structure. Finally, the irregular double-layer grid structure of Yadan sightseeing tower is designed and analyzed, and the key members of the structure are found out, and some of the members are assumed to be damaged. The residual bearing capacity of the structure is evaluated. Through the analysis, we can draw the following conclusion: 1. BRB can not only be used for seismic design of newly built structures, It can also become an important means of seismic reinforcement and reconstruction of existing damaged structures. Through the static safety analysis of the structures strengthened by three schemes under normal working conditions and the dynamic response analysis under the action of different seismic wave records, It is shown that seismic reinforcement of damaged latticed shell structure by BRB can improve the seismic performance of the structure on the premise of ensuring the static safety of the structure in normal use. The larger the span of the latticed shell structure, the higher the acceleration amplitude of ground motion. The better the seismic strengthening effect of restrained buckling braces is, the better the effect of seismic reinforcement is when the yield strength of BRB is 80 MPA / 100 MPa, the cross section size is 0.8 times and 1.0 times the original bar section. In addition, the influence of the lower support on the superstructure should not be ignored in the analysis of the latticed shell structure. For some practical projects, the damage of some members of the structure can be assumed by combining the results of the design and analysis of the loads under various working conditions. The key members of the structure are found by the method of evaluation of the residual bearing capacity of the structure, which provides guidance for the construction and use of the structure in the later stage.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU33

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