高速铁路尼尔森体系系杆拱桥徐变变形影响因素

Influencing factors on creep deformation of tied-arch bridge of Nielsen system in high-speed railway

高速铁路上使用的无砟轨道对桥面线形要求较高,因此计算时需准确预测桥梁徐变产生的影响.以京沪高铁上一座96 m尼森体系系杆拱桥为例,对其按现行中国铁路规范(TB10002.1-2005)与现行中国公路规范(JTG D62-2004)进行模拟施工全过程.计算结果显示,在相同条件下,铁路05规范的徐变终极值比公路04规范大35.19%;在成桥后,30 d加载二期恒载加载以及延长洒水养生时间,可以有效减少混凝土的徐变变形;采取以上措施对主梁应变、吊杆索力以及系杆索力的影响均在8%以内,其中大部分影响值在2%以下.

The influence to bridge deck line induced by creep should be predicted accurately because of the demands of high smoothness and high stability of the ballastless track used in high speed railways.In this paper a 96-meter span tied-arch bridge of Nielsen system is used as an example in which whole process of construction would be simulated according to the current China railway code（TB10002.1-2005） and the current China highway code（JTG D62-2004）.The results show that,under the same condition,the ultimate creep value according to the current China Railway Code is larger by 35.19% than the value according to the current China Highway Code.It is effective to reduce creep deformation of concrete with limited impact（less than 8%） on strain of main girders,suspender force and tie bar force by deferring applying secondary dead load by 30 days after completion of this bridge and prolonging concrete curing duration.