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To improve the simulation calculation accuracy of long-span composite girder bridges during construction and ensure high calculation efficiency, this paper presents a novel algorithm for analyzing internal force redistribution in steel–concrete composite girder bridges. Based on section equivalence theory, the expression describing the internal force distribution of the steel girder and the concrete deck is derived, and a new finite element model of a double-layer element, named virtual double-layer element model, is established. Based on the exponential recursive method of concrete beam element shrinkage and creep effects and the influence mechanism of concrete deck shrinkage and creep in steel–concrete composite girders, an analysis model of composite girder shrinkage and creep is established. Calculation expressions of the equivalent node force increment and fixed-end force increment of the composite girder integral element after conversion of a composite section are derived. The feasibility of the method proposed in this paper is verified through analysis of models of a continuous beam and a cable-stayed bridge. The algorithm was applied to calculate the construction process of the world's largest span cable-stayed bridge, achieving alignment with its design objectives. • An algorithm accurately simulates the continuous combination of double-layer elements and the shrinkage and creep effects. • The computational efficiency of the algorithm is enhanced using an exponential function recursion method. • The algorithm is integrated into a self-developed FEM software and its correctness has been validated. • The algorithm has been applied to calculate the construction process of several composite cable-stayed bridges. [ABSTRACT FROM AUTHOR]

• Fiber end deformation increases the friction during pullout process. • Increasing embedment angle of fiber improves the bond strength. • Optimal silica fume content benefits to improve the bond property. • Steaming curing too long accelerates the hydration and shrinkage cracks progression. • Magnetic nanoparticles enhances the pullout toughness of fiber with no brass-coated. A new single fiber pullout testing method was applied to characterize the interfacial bond performance, which includes the pullout load-slip relationship, pullout energy, bond strength, and fiber utilization ratio, of the steel fiber-matrix in reactive powder concrete (RPC). The bond properties and bond strengthening mechanism were investigated from the perspective of certain parameters, including the fiber type, fiber embedment angle, silica fume content, magnetic nanoparticles content, and curing time. The microstructure of the steel fiber and longitudinal morphology of the tunnel after the pullout test were determined by scanning electron microscope (SEM). In terms of the results, the bond strength of the end-hooked steel fiber is much stronger than that of the straight steel fiber. With the increasing of embedment angle, the ultimate pullout load and pullout energy of straight steel fibers increase, and the interfacial bond strength increases. It is found that the incorporation of silica fume can effectively enhance the matrix strength. In addition, RPC containing 20%∼30% silica fume shows significant improvement in pullout behavior. The appropriate curing age contributes greatly to the hydration reaction and the matrix strength of RPC. Steaming curing for 2 d can effectively improve the interfacial bond performance. A content of 1% magnetic nanoparticles enhances the pullout behavior of straight steel fibers with no brass coating, because the maximum pullout load and pullout energy increase by 33.6% and 79.0%, respectively. The microstructural observations confirm the conclusions regarding the bond mechanism drawn from the pullout tests. In conclusion, the performance of the matrix, the characteristics of the fiber-matrix interface area and the friction of the steel fiber in the tunnel can influence the bond performance of the fiber-matrix interface of RPC. [ABSTRACT FROM AUTHOR]