为研究多塔矮塔斜拉桥主梁的破坏形式和抗弯极限承载力，以宁江松花江特大桥为背景工程，采用ANSYS 软件，分别基于Drucker-Prager 屈服准则和Willam-Warnke 五
参数破坏准则建立两种三维实体有限元模型，分析结构从承受设计荷载至破坏荷载整个过程的受力状态并得到3 种工况下的结构抗弯极限承载力，和现行桥梁规范( JTG D62—2004) 方法的计算值进行了对比． 结果表明: 两种有限元模型的抗弯极限承载力计算值相对规范方法计算值的平均误差分别为2． 7%和6． 5%，最大误差分别为5． 9%和8． 6%，有限元分析结果与规范方法计算值吻合较好; 结构在活载系数小于3 时基本处于弹性状态;中跨跨中加载为该桥安全系数最小的工况，其安全系数为2． 08．

In order to investigate the failure modes and ultimate bearing capacity of the beam of multi-span extradosed bridges,by using ANSYS,two three-dimensional solid element models of the Ningjiang Songhua River Bridge are constructed respectively based on the five-parameter Willam-Warnke yield criteria and the Drucker-Prager yield criteria.Then,the entire load range of the bridge,which is from a design load to a failure load,is analyzed respectively by using the two models.Moreover,the corresponding ultimate bending bearing capacities for the two models under three kinds of conditions are obtained and are compared with the calculated values based on the current bridge code ( JTG D62—2004) .The results show that ( 1) the average errors between the ultimate bearing capacities of the two finite element models and the bridge code results are respectively 2. 7% and 6. 5%,and the corresponding maximum errors are 5. 9% and 8. 6%,which means that the results based on the two finite element models accord well with the bridge code results; ( 2) the structure works at the elastic state when the ratio of the load to the designed live load is less than 3; and ( 3) the structure with the load on its midspan is of a minimum load safety factor of 2. 08.