中文摘要：

为明确钢管混凝土拱桥钢管内核心混凝土徐变对桥梁应力重分布的影响,采用＂按龄期调整模量法＂,分别运用《公路钢筋混凝土及预应力混凝土桥涵设计规范》（JTG D62—2012）中公式计算所得混凝土徐变系数和轴向受压钢管混凝土徐变试验、拱肋徐变试验拟合所得混凝土徐变系数,建立可以考虑混凝土徐变过程的ANSYS模型,分析混凝土徐变对茅草街大桥建造期拱肋下挠的影响;运用拉丁超立方抽样方法,以跨中拱肋挠度和钢管应力为限值,以钢材和混凝土弹性模量、上弦和下弦钢管壁厚、腹管壁厚、徐变模型不确定性系数、核心混凝土弹性模量计算所得不确定性系数和茅草街大桥数值模型不确定性系数为参数,计算得到茅草街大桥服役期内的失效概率。结果表明：在建造期内,以基于拱肋徐变试验得到的混凝土徐变系数来计算跨中拱肋下挠值与实际实测值吻合最好,验证了模型的可靠性和精确性;在服役期内,以拱肋挠度和钢管应力为限值,当服役龄期增加到100年时,桥梁失效概率逐步增大,不同混凝土徐变系数的计算结果差异较大;以挠度为限值时,分别利用式（1）、（2）、（6）计算得到的失效概率为0.311,0.013 8和0;以应力为限值时,分别利用式（1）、（2）、（6）计算得到的失效概率为0.499,0.225和0.165 2。因此对于钢管混凝土拱桥的徐变可靠度分析来说,关键之处在于选择正确的混凝土徐变模型。

英文摘要：

In order to investigate the creep effect of the core concrete on construction period and service performance of concrete-filled steel tubular arch bridge,by using＂adjusting valid modulus depending on age＂method,the creep coefficients derived by Code for Design of Highway Reinforce Concrete and Prestressed Concrete Bridges and Culverts（JTG D62—2012）,creep experiment of the concrete-filled steel tube under axial compression and arch rib were applied to establish the ANSYS model,putting creep processes of concrete into consideration to analyze the creep effect of the concrete on the down deflection of main arch rib of Maocaojie bridge during the construction.The reliability analysis was conducted by Latin hypercube sampling method basedon the functions of deflection and steel stress of mid-span arch rib to predict the failure probability of Maocaojie bridge during the service period,taken elasticity modulus of concrete and steel,tube wall thickness of upper and lower chords tubes,ventral tubes,uncertain coefficients of creep model,uncertain coefficients calculated by the elastic modulus of the core concrete and uncertain coefficients of FE model of Maocaojie bridge as parameters.The results show that during the construction,the arch deflection values,calculated by the creep coefficient of the creep test of arch rib,are coincident with the measured values,which verifies the applicability and accuracy of the developed model.During the service period,when the service limits increase to 100 years,the failure probability of bridge gradually increases and differences among results calculated by different creep coefficients of concrete are obviously large,taken rib deflection and stress as limits.According to Equation（1）,（2）and（6）,the failure probability of the bridge is 0.311,0.013 8and 0based on the rib deflection limits,and is 0.499,0.225 and 0.165 2based on the stress limits.So the key problem is to choose the right creep model for creep reliability analysis of concrete-filled steel tubular bridge