系杆拱顶推施工方案及力学性能研究

Analysis of jacking construction scheme and mechanical properties of tied arch bridge

为了探讨系杆拱结构的顶推方案及在顶推过程中的受力特点和设计要点,以某系杆拱桥的整体顶推施工工程为例,建立有限元模型,分析了系杆拱及导梁在不同顶推方案过程中的最值应力分布及挠度变形情况。研究结果表明:原吊杆连接方案(方案一)下,主梁及导梁变形过大,主梁应力过大,方案不可行,可通过增加梁高或者板厚来降低应力及变形,然而该法会造成外形不美观、造价偏高等情况;采用临时撑杆连接方案(方案二)时,受力得到优化,方案可行,然而靠近临时撑杆和端横梁的拱肋会出现较大应力,靠近顶推端部的两根临时撑杆中间主梁处会出现较大应力和变形;在导梁范围内,导梁端部会出现最不利挠度,需要注意控制导梁的整体刚度以及辅助墩上装置的竖向调节量,以免导梁和桥墩相撞。

In order to investigate the jacking scheme of tied arch structures and the stress characteristics and design points in the process of jacking,a tied arch bridge is taken as an example,and a finite element model is established to analyze the maximum stress distribution and the deflection deformations of the tied arch and the guide beam in different jacking schemes.The results show that for the original scheme of the suspender connection(Scheme 1),the deformations of the main beam and the guide beam are excessively large,the stresses of the main beam are also excessively large,and therefore the scheme is not feasible.The stress and deformation can be reduced by increasing the height of the beam or the thickness of the plate,but they cause the appearance unattractive and the cost high.When the temporary strut connection scheme(Scheme 2)is adopted,the force is optimized and the scheme is feasible.However,the arch rib near the temporary strut and the end beam have larger stresses and the middle main beam of the two temporary struts near the jacking end have larger stresses and deformations.Within the guide beam range,the most unfavorable deflection occurs at the end of the guide beam.It is necessary to control the overall stiffness of the guide beam and the vertical adjustment of the auxiliary pier to avoid the collision between the guide beam and the pier.