A Multi-Technique Hybrid Method for the Widening and Splicing of New and Old Beam Bridges

With the rapid increase in the urban traffic volume, the traffic capacity of existing bridges could not meet the demands of urban planning in many cities, leading to the problem of reconstruction or expansion. Considering the sustainability principle in bridge structure construction while minimizing the environmental implications of the construction activities, a multi-technique hybrid method for the widening and splicing of new and old beam bridges was proposed. Firstly, according to the stress equations of the splicing interface between the new and old bridges, the control condition for the selection of the splicing materials was found, and a selection method based on the maximum stress at the splicing interface of the materials was proposed. Then, based on the control condition of the foundation settlement of the new bridges, the geometric parameters of the splicing structures, and the mechanical parameters of the splicing materials, equations for the minimum reinforcement ratio were derived according to the allowable stress value of the splicing materials. Lastly, the equivalent analogic orthotropic plate model of the splicing bridges was built, and based on that, a calculation method for the quantity of the splicing diaphragms was proposed. Also, the effectiveness of the proposed method was validated through a reconstruction and expansion project in Guangdong Province. The results showed that the maximum foundation settlements of the new bridges were smaller than the assumption values of the calculation after reconstruction of the old bridges, and no observable cracks were found in the splicing structures. The proposed method could serve as a reference for similar structure designs.