中承式系杆拱桥结构优化设计

Optimization Design of Half-Through Tied Arch Bridge Structure

以邓家窑大桥为背景,研究小边跨、边跨仅有桥面系压重、依靠系杆力克服拱脚水平推力的三跨中承式系杆拱桥的桥型及结构参数的优化。优化后的桥型按部分推力拱设计,系杆力只平衡大部分恒载引起的水平推力;拱肋采用混凝土和钢箱的混合结构;边拱、刚性纵梁和主拱拱脚段组成一个三角刚架,整体承担系杆力。对拱肋内倾角、矢跨比、拱轴系数、系杆力和基础形式等结构参数进行研究,结果表明,拱轴系数对拱脚水平推力的影响很小;系杆力是克服拱脚水平推力的最有效方式,通过技术和经济两方面比较,最终选定4排桩+15 000 kN系杆力的基础形式与系杆力最优组合形式。

Against the background of the Dengjiayao Bridge, the authors herewith conduct a study of optimization of the bridge type and structural parameters of a three-span half-through tied arch bridge that has short side spans, utilizes floor system only as counterweight on the side spans and overcomes horizontal trust at arch springers by the tied member force. The bridge type after optimization is designed in accordance with the partial thrust arch and the tie member force is used to only balance the horizontal thrust caused by most of the dead load. The hybrid structure of concrete and steel boxes are used for the arch ribs, the side arches, rigid longitudinal beams and the arch springers of the main arch are in all formed into a triangle frame to integrally carry the force from the tied members. The structural parameters of the inward inclination angles of the arch ribs, rise-to-span ratio, arch axis coefficients, tied member force and foundation types are studied as well. The results of the study indicate that the influence of the arch axis coefficients on the horizontal thrust of the arch springers is very little and the tied member force is the most effective force that overcomes the horizontal thrust. The comparison of both the technical and economic aspects finally determines the foundation type of 4 rows of piles plus the 15000 kN tied member force and the best combination of the tied member force.