拱肋外倾角对异形空间拱桥受力的影响

Influence of Camber Angles of Arch Ribs on Mechanical Behavior of Irregularly-Shaped Spatial Arch Bridge

以建设中的九堡大桥主桥为背景,研究外倾式拱桥的拱肋处于不同倾斜角度时对结构受力产生的影响。采用ANSYS建立该桥三维有限元模型,计算在仅有恒载作用时主拱肋外倾角分别为0°、5°、12°、20°四种工况下该桥各部分的受力,并分析在成桥状态下该桥的第1类稳定问题。分析结果表明:主拱肋外倾角变化对主、副拱肋,主梁以及主、副拱肋间连杆的内力影响较大;当主拱肋外倾角在5°和12°时结构稳定系数明显高于其他情况;主拱肋外倾角由0°增加到20°时,结构第一阶失稳模态均为拱肋体系的整体弯扭失稳。

The main bridge of the Jiubao Bridge that was being constructed was cited as an example and the influence produced by the outward inclined arch ribs of the arch bridge in a state of different camber angles on the mechanical behavior of the bridge structure was studied.The ANSYS was used to establish the three-dimensional finite element models for the bridge,the force conditions of various parts of the bridge under the four cases that the camber angles of the main arch ribs were respectively 0°,5°,12° and 20° under the action of only dead load were calculated and the Category I Stability issue of the bridge in completion state was analyzed.The results of the analysis reveal that the influence of variations of the camber angles on the main and subsidiary arch ribs,main girder and on the internal force in the connection members between the main and subsidiary arch ribs is great.At the time the camber angles are 5° and 12°,the stability coefficients of the structure are obviously greater than those of other cases and at the time the camber angle is increased from 0° to 20°,the first order instability modes of the structure are all of the global bending and torsion instability of the arch rib system.