Abstract: Application of virtual load method in stress analysis and calculation of steel-concrete composite beam was studied. The calculation formula of temperature difference stress of simply supported composite beam based on virtual load method was derived. Combined with the effective elastic modulus method, the calculation formula of shrinkage stress of simply supported composite beam based on virtual load method was derived. Taking a 45 m span I-shaped simply supported steel-concrete composite beam as an example, the temperature difference stress and shrinkage stress of the composite beam were calculated by using the virtual load method, ANSYS finite element method and the calculation formula recommended by The Railway Composite Beam Design Regulations (TBJ 24—89), and a comparative analysis was carried out. The research results show that: for the calculation results of the temperature difference stress of the composite beam, the error between the virtual load method and the ANSYS finite element method is 1.6%, which shows that the virtual load method can accurately calculate the temperature difference stress of the composite beam. Compared with the calculation results of the calculation formula recommended by The Railway Composite Beam Design Regulations (TBJ 24—89), the shrinkage strain is more fully considered in the stress calculation formula of virtual load method.

Key words: bridge engineering; steel-concrete composite beam; virtual load method; temperature difference stress; shrinkage stress

摘要： 研究了虚拟荷载法在钢-混凝土组合梁应力计算中的应用。推导了基于虚拟荷载法的简支组合梁温差应力计算式；结合有效弹性模量法，推导了基于虚拟荷载法的简支组合梁收缩应力计算式；以某一45 m跨径工字简支钢-混凝土组合梁为例，分别采用虚拟荷载法、ANSYS有限元法及TBJ 24—89《铁路结合梁设计规定》推荐的计算式计算组合梁的温差应力及收缩应力，并进行了对比分析。研究表明：对于组合梁温差应力计算结果，虚拟荷载法与ANSYS有限元法的误差为1.6%，说明虚拟荷载法能准确计算组合梁温差应力；与TBJ 24—89《铁路结合梁设计规定》计算式的计算结果相比，虚拟荷载法应力计算式对收缩应变的考虑更为充分。

关键词: 桥梁工程；钢-混凝土组合梁；虚拟荷载法；温差应力；收缩应力