Numerical and Theoretical Analysis of Slab Transverse-Moment Distributions in Twin-Girder Crossbeam Composite Bridges

Abstract

In twin-girder crossbeam composite (TGCBC) bridges, the concrete slab supported only by steel plate girders is typically regarded as a one-way slab, and its transverse bending moments are essential for structural optimization and evaluation. However, little research has been conducted on the transverse-moment distribution of the slab in TGCBC bridges and the slab moment prediction method capable of considering the effects of actual configurations and dimensions is not available in the current TGCBC bridge design practice. Recommendations by design codes for continuous slabs in steel or concrete bridges have not considered the structural characteristics of TGCBC bridges, which may result in an uneconomical or unsafe slab design for TGCBC bridges. In this paper, finite-element analyses were conducted on an existing TGCBC bridge to investigate the transverse-moment distribution of its concrete slab under external loads. A simplified method based on a frame model for predicting the transverse-moment distribution coefficients was then proposed. The effects of geometric parameters and cracking of concrete slabs on the transverse-moment distribution coefficients were also examined through a parametric analysis. The analysis results show that the transverse bending stiffness of steel plate girders, which is mainly determined by the layouts of web transverse stiffeners and crossbeams, has a significant influence on the transverse-moment distribution of the slab. Additionally, the distribution coefficients are also dependent on the geometric parameters of TGCBC bridges as well as the magnitude of external loads. The results also show that the transverse-moment distribution coefficients could be precisely estimated by the proposed simplified method.