台风区钢管格构支架稳定性和优化设计分析

以台风区的平潭海峡大练岛特大桥新建工程中现浇公路桥的钢管格构支架体系为研究背景,对钢管格构支架稳定性进行分析,通过Midas Civil软件建立钢管格构支架体系空间有限元模型,从不同的肢数、节段长度、高度等参数进行分析,并对四肢格构支架进行均匀流风场作用下的风洞试验。计算结果表明:当钢管结构的壁厚与直径比δ/d一定时,支架结构的临界屈曲荷载系数随着钢管直径的增大而增大,整体呈指数上升趋势;六肢与四肢钢管格构支架临界荷载系数相差不大,四肢钢管格构支架是最经济支架结构;当支架总高度小于70 m时,钢管格构支架结构基本能满足结构稳定性要求;支架钢管立柱横向间距在5~7 m时,其稳定性呈现较快的上升趋势,横向间距为7 m左右时,支架稳定性最好。风洞试验结果能反映四肢格构支架的实际受力特性,并指导四肢格构支架现场实际施工。该分析可为类似钢管格构施工支架的设计提供参考。

Analysis on Stability and Optimization Design of Steel Pipe Lattice Support in Typhoon Area

Based on the research background of steel pipe lattice support system of cast-in-place highway bridge in the new construction project of Pingtan Strait Dalian Island Bridge in typhoon area,the stability of steel pipe lattice support is analyzed.The spatial finite element model of steel pipe lattice support system is established by Midas Civil software,and the parameters such as different limb number,segment length and height are analyzed,and the wind tunnel test under the action of uniform flow field is carried out on the four limbs lattice support.The calculation results show that the critical buckling load coefficient of the support structure goes up with the increase of the diameter of the steel pipe when the ratio of wall thickness to diameter of steel pipe structure is constant,and the whole structure shows an exponential upward trend.There is no significant difference in the critical load coefficient of the six limbs and four limbs steel tube lattice support,and the four limbs steel pipe lattice support is the most economical support structure.When the total height of the support is less than 70 m,the steel pipe lattice support structure can basically meet the structural stability requirements.When the transverse spacing of the steel pipe column is 5~7 m,the stability of the support shows a rapid upward trend,when the transverse spacing is about 7 m,the support is the most stable.The results of wind tunnel test can reflect the actual stress characteristics and guide the field construction of four-limb steel pipe lattice support.The analysis could provide a theoretical basis for the design of similar steel pipe lattice construction support.