基于新规范的哑铃型拱肋徐变效应分析

Analysis on Creep Effect of Dumbbell-shaped Section Based on New Design Code

针对钢管混凝土拱桥由于钢管内混凝土徐变导致的拱肋下挠和截面应力重分布问题,基于《公路钢管混凝土拱桥设计规范》(JTG-T D65-2015),考虑哑铃型拱肋截面的截面特性,计算新规范下的徐变系数,通过对一座152米钢管混凝土拱桥建立全桥的有限元模型,并与按原JTG D62-2004路桥规范中的徐变系数计算所得出的结果进行对比分析。结果表明:针对钢管混凝土的JTG-T D65-2015规范的徐变系数比针对普通钢筋混凝土的JTG D62-2004规范的徐变系数小。按JTG-T D65-2015规范计算的由徐变引起的拱肋下挠值比按JTG D62-2004规范计算所得值小10%左右,徐变引起钢管截面应力增大和混凝土截面应力减小,按JTG-T D65-2015规范计算得到的钢管应力增大值比按JTG D62-2004规范计算所得到的值小10%-15%左右。

Aiming at the problem of the deflection and the stress redistribution of arch rib of concrete filled steel tubular arch bridge which caused by the concrete creep, based on new design code specifications for design of highway concrete-filled steel tubular arch bridges, in consideration of section properties of the dumbbell-shaped section, the finite element model of a 152-m span bridge was built, comparative analysis is made with the results by using previous code that published in 2004. The results showed that the creep coefficient of 2015 specification is less than that of 2004 specification. The value of deflection of arch rib that caused by creep by the 2015 specification is less than that by t he 2004 specification in 10%.Creep can caused the stress of steel tubular increased and the stress of concrete decreased, the increment value of the stress of steel tubular that calculation by the 2015 specification is less than the value that by the 2004 specification in 10% ~ 15%.