滚动式张拉索节点弦支穹顶结构分析及试验研究

发布时间：2018-04-24 19:01

  本文选题：滚动式张拉索节点 + 弦支穹顶　； 参考：《天津大学》2015年博士论文

【摘要】：弦支穹顶结构施工的关键环节在于将预应力设计值准确地施加到结构中去,工程中常采用张拉环索方式施加预应力。为减小索撑节点处的摩擦损失,可在撑杆下节点处运用滚动式张拉索节点。通过试验方法研究这种引入了滚动式张拉索节点的弦支穹顶结构的力学性能,并定量对比分析弦支穹顶与上部单层网壳的静力性能,对评估滚动式张拉索节点弦支穹顶的高效能性具有重要意义。由于椭球形弦支穹顶自身的几何特征,张拉环索这一高效施工方式能否直接应用于椭球形弦支穹顶,直接影响了弦支穹顶的推广应用。滚动式张拉索节点的引入虽能有效减小摩擦损失,但既有研究表明其不能完全克服摩擦,因此在结构的有限元分析中如何在单元层面考虑拉索与撑杆下节点间的摩擦,以准确评估结构的整体性能。以及张拉过程中的预应力随机误差对结构整体性能的影响,都是弦支穹顶结构体系的理论研究过程中需要解决的问题。本文即针对这种采用了新型滚动式张拉索节点的弦支穹顶结构展开了深入的研究。滚动式张拉索节点对结构性能改善程度的最直接衡量标准是检测出节点两侧索力值,以计算该节点处的预应力摩擦损失值。基于直接测量法提出了一种适用于弦支穹顶结构试验研究的索力测试方法,并通过试验研究、理论分析验证其可靠性及应用范围。提出了一种适用于张弦结构体系的等效摩擦单元,进而建立了张弦结构考虑拉索与撑杆下节点间摩擦的有限元分析方法,并通过试验研究验证了该摩擦单元的适用性。将等效摩擦单元应用到张弦桁架结构的有限元分析中,得到了预应力摩擦损失对张弦桁架结构整体性能的影响规律。分别开展了带滚动式张拉索节点的弦支穹顶结构和其上部单层网壳结构的理论分析和试验研究,并对比分析了弦支穹顶和相应单层网壳的静力性能。基于单层网壳内的力流传递规律和杆件的空间位置关系,提出了一种杆件内力近似计算方法,推导了网壳在球坐标系下的有限元计算方法;建立茌平体育馆弦支穹顶的1:10缩尺模型,拉索张拉前开展了单层网壳的静力试验,得到了单层网壳在半跨和全跨荷载作用下的内力分布特征,同时验证了理论分析的正确性;开展了弦支穹顶的张拉试验和静力试验,采用高精度的激光跟踪仪全程跟踪测量关键测点位移,揭示了弦支穹顶张拉过程中的结构内力和变形变化规律,得到了弦支穹顶在全跨与半跨荷载作用下的内力分布特征。针对椭球形弦支穹顶结构同圈环索内力有可能不等,从而不能采用张拉环索这一高效施工方式的情况,分析了3种常见椭球形弦支穹顶结构索撑体系的初始平衡态,得到了椭球形索撑体系同圈环索内力相等的必要条件;针对同圈环索内力不等的案例,采用扩展力密度法对索撑体系重新找形,得到了同圈环索内力相等时的形态;根据环索内力的分布规律提出了张拉环索时张拉点的合理布置建议。弦支穹顶结构的预应力误差不可必免地存在,基于概率统计原理,以一实际工程为背景,研究了弦支穹顶结构的各项力学性能对环索内力随机误差的敏感性,以及随机误差对各项力学性能的具体影响程度。明确了弦支穹顶结构最外圈环索在结构中的重要作用以及对结构的重要影响程度,提出了弦支穹顶预应力施工过程中严格控制最外圈环索内力张拉精度的建议。
[Abstract]:The key to the construction of the stringed dome is to apply the prestress design value to the structure accurately. In the project, the tensioning cable is often used to apply the prestress. In order to reduce the friction loss at the bracing joints, the rolling tension cable joints can be applied to the joints under the braces. The rolling tension is introduced through the test method. The mechanical properties of the chord dome structure of the cable node and the quantitative comparison and analysis of the static performance of the chord dome and the upper single layer reticulated shell are of great significance to the evaluation of the high efficiency of the chord dome of the rolling tension cable. The ellipsoidal dome directly affects the extension and application of the chord dome. The introduction of the rolling tension cable node can effectively reduce the friction loss, but the research shows that it can not completely overcome the friction. Therefore, in the finite element analysis of the structure, how to consider the friction between the cables and the braces at the element level in the finite element analysis is to accurately evaluate the knot. The overall performance of the structure and the influence of the prestress random error on the overall performance of the structure are all problems to be solved in the theoretical study of the chord dome structure system. This paper is aimed at the deep research on the string dome structure which adopts the new type of rolling tension cable joints. The most direct measure of the improvement of the structural performance is to detect the cable force values on both sides of the node to calculate the loss of the prestressed friction loss at the node. Based on the direct measurement method, a cable force test method suitable for the test study of the chord dome structure is proposed. The reliability and application model of the test is verified by theoretical analysis. An equivalent friction unit suitable for the tension string structure system is proposed, and a finite element analysis method is established for the tension string structure to consider the friction between the cables and the braces. The applicability of the friction element is verified by the experimental study. The equivalent friction unit is applied to the finite element analysis of the tension string truss structure. The influence of the stress friction loss on the overall performance of the tension string truss structure. The theoretical analysis and experimental study of the chord dome structure with the rolling tension cable joints and the upper single layer reticulated shell are carried out respectively, and the static performance of the chord dome and the corresponding single layer reticulated shell is compared and analyzed. The approximate calculation method of the internal force of the rod is presented, and the finite element calculation method of the reticulated shell in the spherical coordinate system is derived. The 1:10 scale model of the chord dome in Chiping gymnasium is established. The static test of the single layer reticulated shell is carried out before the cable tension is drawn, and the single layer reticulated shell is subjected to half span and full span load. The characteristics of the internal force distribution and the correctness of the theoretical analysis are verified. The tension test and static test of the chord dome are carried out. The displacement of the key points is measured by a high-precision laser tracker, and the structural internal force and the deformation and transformation law of the chord dome are revealed, and the full span and half span load of the chord dome are obtained. The initial equilibrium state of the bracing system of 3 common ellipsoidal stringed dome structures is analyzed. The ellipsoidal bracing system is equal to the inner force of the ring cable. According to the case of unequal inner force in the same ring, the extended force density method is used to find the shape of the cable bracing system again, and the shape of the cable internal force is equal. According to the distribution law of the ring cable internal force, the reasonable arrangement of the tension point of the tension ring is put forward. The prestress error of the string dome structure can not exist without necessity. Based on the principle of probability and statistics and taking a practical project as the background, the sensitivity of the mechanical properties of the chord dome to the random error of the ring cable internal force and the specific influence of the random error on the mechanical properties are studied. The important role of the outer ring cable in the stringed dome structure and the important shadow on the structure are clarified. It is suggested that the tensioning accuracy of the outer ring cable should be strictly controlled during the prestressing construction of the suspended dome.

【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU399
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本文编号：1797835