【作者】 王琼；

【导师】 邓华；

【作者基本信息】 浙江大学 ， 结构工程， 2013， 博士

【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。更多还原

【Abstract】 Suspendome is a new type large-span space structure with superior capability. In this paper, characteristics of the elasto-plastic response under the intensity of fortification and rare earthquake as well as problems of seismic design of this kind of structures are studied. Specifically, the main work includes the following four aspects:(1) Intensity measure of artificial seismic waves are studied. The seismic response caused by different artificial seismic waves, which were generated by the same response spectrum and modulated according to a single intensity measure(IM), varies distinctly. Besides, the variations of seismic response are sensitive to the natural vibration period of structures and durations of artificial seismic waves. An improved response spectrum IM is put forward. When the amplitudes of artificial seismic waves were modulated by the improved IM, differences of structural seismic responses caused by different artificial seismic waves are reduced obviously, and the level varies lightly with the natural vibration period of structures In addition, the variations of structural seismic responses under artificial seismic waves with different durations reduced significantly by using the improved IM.(2) Efficiency of segmentation for round steel bar beam element is studied. It shows that, when the rod is divided into four three-node beam elements and the ratio of the length of end element to that of the central unit is1:4, response of elasto-plastic buckling under compression and bending can be efficiently simulated. The effect of member’s initial curvature on buckling capacity and elasto-plastic seismic response is analyzed.In case of the larger intensity earthquake, the seismic response of the structure will vary greatly according to the shape, direction and peak value of initial curvature. In addition, displacement response’s difference (DRD) method is put forward in order to find the critical point of dynamic instability.(3) By means of24suspendome models, effect of initial pretension of cable-bar system, rigidity and symmetry of substructure, connection condition of abutments, rise-span ratio and criteria of cross section checking on the structural elasto-plastic dynamic behaviors are analyzed. The results reveal that, for most of models, the members with residual plastic strains mainly located in the central of the roof under the intensity of fortification and rare earthquakes. The dynamic behaviors of suspendomes are more sensitive to the symmetry of substructure and the rise-span ratio of roof. A reference index, the ratio of residual ultimate bearing capacity, is put forward in order to evaluate the damage level of suspendomes. It reveals that the ratio of residual ultimate bearing capacity for the suspendome under7-degree rare earthquake is very high. However, it reduces much under8-degree rare earthquake. Furthermore, by the analysis of the ratio of residual ultimate bearing capacity of24suspendome models, it is suggested that the member’s cross sections of the upper reticulated shell should be checked against frequent earthquake in7-degree district and the intensity of fortification earthquake in8-degree district.(4) Changes of cable force in suspendomes after the intensity of fortification and rare earthquakes are investigated. It shows that, after the intensity of fortification earthquakes, the cable force does not change in most of those models designed according to elastic behavior in7-degree frequent earthquake, and the changes of cable force in most of those models designed according to elastic behavior in8-degree frequent earthquake, are less than10%. After rare earthquakes, the changes of cable force in most of those models designed according to elastic behavior in7-degree frequent earthquake are less than10%, and in most of those models designed according to elastic behavior in8-degree frequent earthquake are more than20%and some cables may even be totally relaxed. When according to elastic behavior in7-degree the intensity of fortification earthquake, the changes of cable force reduce much. Cable layout, asymmetry of substructure and the rise-span ratio of upper dome are important influence factors to the loss of cable force. It is suggested that the ratio of cable force’s loss can be regard as a reference index for performance-based seismic design of suspendomes.更多还原