弦支穹顶的弹塑性抗震性能研究

发布时间：2018-05-02 23:34

本文选题：弦支穹顶 + 弹塑性地震响应　；参考：《浙江大学》2013年博士论文

【摘要】：弦支穹顶是一种性能优越的新型大跨度空间结构体系,本文对此类结构在中震和大震作用下的弹塑性响应特点及其抗震设计问题进行了研究,主要工作包括以下四个方面： (1)对人工地震波的强度指标进行了研究。发现对于由同一反应谱生成的不同人工波,当按单一强度指标进行调整后会使得结构地震响应出现不可忽视的差异,而且这种差异对于结构自振周期或人工波持时长短较为敏感。本文提出了一种基于反应谱指标的改进强度指标。采用该改进指标对人工波进行调幅,发现在不同地震波下的结构响应差异明显减小,且差异程度也不因结构自振周期的不同而有较大的波动。此外,结构的地震响应也不会因为人工波持时取值的长短而产生较大差异。 (2)对弦支穹顶弹塑性分析的精细化建模问题开展了研究。考察了圆钢管杆件单元划分的有效性,发现当杆件划分为4个三节点Timshenko梁单元且端部与中部单元长度比值为1：4时,可以有效地模拟杆件在复杂压弯状态下的弹塑性屈曲反应。分析了杆件初弯曲对弦支穹顶弹塑性响应及极限承载能力的影响,发现当地震动强度较大时,结构的位移响应会随着杆件初弯曲的形状、方向和幅值的变化产生较大差异。此外,还提出了一种能较准确定位结构动力失稳临界点的位移响应差法。 (3)借助24个算例,系统地分析了初始预张力、下部结构刚度和对称性、支座连接条件、网壳矢跨比以及杆件截面验算标准等因素对中震和大震下弦支穹顶结构的动力响应特性的影响。研究表明,中震和大震作用下上部网壳的塑性杆件主要出现在跨中而不在临支座区域；下部结构的对称性和网壳矢跨比对结构的弹塑性响应最为敏感。提出了个极限承载力剩余率指标用以定量评价弦支穹顶的震后破坏程度,并发现7度大震作用下结构的极限承载力剩余率依然很高,但是8度时明显降低。进一步根据24个算例的结构极限承载力剩余率分析,建议7度时弦支穹顶的杆件截面可采用小震弹性设计,8度时则采用中震弹性设计。 (4)对中震和大震作用后弦支穹顶结构的索力变化进行了考察。研究表明,中震作用后,按7度小震弹性设计的结构基本未出现索力变化,8度小震弹性设计的结构索力变化基本在10%以内。大震作用后,按7度小震弹性设计时结构索力变化率基本在10%以内,而8度小震弹性设计时的结构索力变化率多数在20%以上,有些还出现了完全损失的情况。当采用中震弹性设计后,弦支穹顶的索力变化率会明显减小,多数模型在20%以内。布索方式、下部结构的对称性以及网壳的矢跨比是影响结构索力损失的主要因素。建议以索力损失率作为弦支穹顶结构抗震性能化设计的参考指标。
[Abstract]:Chord dome is a new type of large span spatial structure system with superior performance. This paper studies the elastoplastic response characteristics and seismic design of this kind of structures under the action of moderate and large earthquakes. The main work includes the following four aspects: 1) the intensity index of artificial seismic wave is studied. It is found that for different artificial waves generated by the same response spectrum, the seismic response of the structure can not be ignored when adjusted according to a single strength index. Moreover, the difference is sensitive to the period of natural vibration or the duration of artificial wave. In this paper, an improved strength index based on response spectrum index is proposed. Using the improved index to adjust the amplitude of artificial wave, it is found that the difference of structural response under different seismic waves is obviously reduced, and the difference degree does not fluctuate greatly because of the different natural vibration period of the structure. In addition, the seismic response of the structure does not vary greatly because of the duration of the artificial wave. 2) the fine modeling of elastic-plastic analysis of dome is studied. The validity of the element partition of circular steel tube members is investigated. It is found that when the members are divided into four three-node Timshenko beam elements and the ratio of the length of the end to the middle element is 1:4, the elastic-plastic buckling response of the members under complex compression and bending conditions can be effectively simulated. The influence of the initial bending of the bar on the elastoplastic response and ultimate bearing capacity of the dome is analyzed. It is found that the displacement response of the structure will vary with the shape, direction and amplitude of the initial bending of the bar when the local vibration intensity is large. In addition, a displacement response difference method is proposed, which can accurately locate the critical point of dynamic instability of structures. (3) with the aid of 24 examples, the initial pretension, stiffness and symmetry of the lower structure, and support connection conditions are systematically analyzed. The influence of factors such as the rise-span ratio of reticulated shell and the bar cross section checking standard on the dynamic response characteristics of the dome structure under moderate and large earthquakes. The results show that the plastic members of the upper latticed shell are mainly found in the middle span and not in the immediate support area under the action of moderate and large earthquakes, and the symmetry of the substructure and the elastic-plastic response of the latticed shell are the most sensitive. Put forward It is found that the residual ratio of ultimate bearing capacity of the structure is still very high under the action of 7 degrees earthquake, but it is obviously decreased at 8 degrees. According to the analysis of the residual rate of ultimate bearing capacity of 24 examples, it is suggested that the member section of the dome can be designed by small earthquake elastic design at 8 degrees and medium earthquake elastic design at 7 degrees. The variation of cable force of the dome structure after the action of moderate earthquake and strong earthquake was investigated. The results show that, after the action of moderate earthquake, the structure designed according to the small earthquake of 7 degrees has no change of cable force basically. The change of cable force of the elastic design of small earthquake of 8 degrees is less than 10%. After the large earthquake, the change rate of the structural cable force is within 10% in the elastic design of the small earthquake of 7 degrees, while the change rate of the structural cable force in the elastic design of the small earthquake of 8 degrees is more than 20%, some of them have been completely lost. The variation rate of cable force of the dome will be reduced obviously when the meso-seismic elastic design is adopted, and most of the models are less than 20%. The cable arrangement, the symmetry of the substructure and the rise-span ratio of the latticed shell are the main factors affecting the cable force loss of the structure. It is suggested that the loss rate of cable force be used as the reference index for seismic performance design of dome structures.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU352.11;TU399

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