摘要
为确定悬索桥主缆对桥塔的约束刚度,假定主缆线形为抛物线,通过变分原理获得主缆垂度改变与其跨长及水平力变化之间的关系。运用能量守恒原理,桥塔在活载作用下发生变形并引起主缆线形改变,与此同时,外力做功转化为结构重力势能及主缆的弹性应变能并提供对桥塔的约束作用,据此推导了主缆约束刚度解析表达式。为验证公式精度,建立悬索桥有限元模型进行验证,并与已有公式进行了对比,研究了边中跨比、中跨垂跨比以及主缆应力水平对边跨主缆纵向刚度的影响,给出了可直接用于估算边跨主缆刚度的相关图表。研究结果表明:采用提出的公式计算主缆初始切线刚度具有较高精度;忽略主缆的弹性变形对于中跨主缆刚度影响不大,对边跨主缆影响较大;边跨主缆的约束刚度与单位桥长恒载成正比,随着中跨垂跨比及边中跨比的减小而增大。
In order to determine the restraint stiffness of main cable on bridge tower in suspension bridge, assuming that the shape of main cable was a parabola, the relationship between sag change of the main cable and variation of its span length and the horizontal force was obtained by the variational principle. Applying the principle of conservation of energy, the main cable shape changed when the bridge tower deformed under live load. At the same time, the external force doing work was converted to gravitational potential energy and elastic strain energy of the main cable, which provided restriction effect for bridge tower. On this basis, an analytical expression was derived for the restraint stiffness of main cable. The formula was verified by a finite element model for suspension bridge and compared with existing formulae. The effects of the following parameters on longitudinal stiffness of main cable in side span were analyzed, ratio of side to main span, rise-span ratio and stress level of the main cable. Related charts were given to directly estimate the stiffness of main cable in side span. The results show that the formula has a high accuracy to calculate the initial tangent stiffness of main cable. Elastic deformation of the main cable affects a little to the main cable stiffness of mid span, while for side span, it has a great influence. Restraint stiffness of main cable in side span is proportional to constant load of bridge unit long, which increases with the decrease of rise-span ratio and ratio of side to main span.
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2015年第8期59-66,共8页
China Journal of Highway and Transport
基金
国家重点基础研究发展计划("九七三"计划)项目(2013CB036303)
关键词
桥梁工程
悬索桥
能量原理
纵向刚度
主缆
bridge engineering
suspension bridge
energy principle
longitudinal stiffness
main cable
