基于精细模型的波形钢腹板斜拉桥收缩徐变效应分析

Shrinkage and Creep Effect of Corrugated Steel Webs Cable-Stayed Bridge Based on Fine Model

为了解决按龄期调整有效模量法计算混凝土徐变时存在卸载后徐变即恢复的缺陷,以及通用计算程序ANSYS等软件没有专用混凝土徐变分析模型的问题,提出了基于按龄期调整的修正模量法以确定蠕变系数的混凝土徐变计算方法,推导了混凝土徐变系数的求解公式,编制了计算程序;结合已有理论与试验数据验证了计算方法的有效性;计算了波形钢腹板箱梁无背索斜拉桥收缩徐变效应。结果表明:在收缩徐变效应影响下,结构内力重分配明显,多数结构响应在成桥1年内充分发展至10年增量值的60%以上;徐变作用下有索跨跨中底板、主梁根部截面底板、主塔有索侧根部位置应力逐步增加,应重点关注其受力安全问题。

In order to overcome the defect of creep recovery after unloading in the calculation of concrete creep by using the age-adjusted effective modulus method,and solve the problem of the general calculation program such as ANSYS without a dedicated concrete creep analysis model,the calculation method of concrete creep based on the principle of effective modulus method adjusted by age to determine the creep coefficient was proposed.The formula for calculating the creep coefficient of concrete was derived,and a calculation program was developed.The effectiveness of the proposed calculation method was verified by combining existing theory and experimental data.The shrinkage and creep effects of a corrugated steel web box girder cable-stayed bridge without back cables were calculated.The results show that under the influence of shrinkage and creep effect,the internal force redistribution of the structure is obvious,and most structural responses have been fully developed to more than 60%of the 10-year incremental value within one year of completion of the bridge.Under the action of creep,the stresses gradually increases at the mid span bottom plate of the cable span,the bottom plate of the main beam root section,and the root position of the cable side of the main tower.The force safety issues at these locations should be focused on.