Integrated Numerical Analysis of the Structural Behavior of a Multi-Span Prestressed Concrete Bridge under Road Traffic Loads and Time-Dependent Effects: A Case Study of the Bantoum Bridge, Cameroon

Abstract

Assessing the performance of multi-span prestressed concrete bridges requires the combined consideration of traffic-induced actions, prestressing, the mechanical properties of materials, and the time-dependent effects of concrete. This study investigates the structural behavior of the deck of the Bantoum River Bridge, located along National Road RN4 in Cameroon. The bridge consists of five 30-m spans, four prestressed concrete main girders, and a reinforced concrete deck slab. A three-dimensional numerical model was developed using MIDAS Civil 2022 based on the actual geometry of the structure, the mechanical properties of the materials, the support conditions, and the prescribed design actions. The LM1 and LM3 road traffic load models, wind actions, and time-dependent effects associated with concrete creep and shrinkage were considered. The results show that the most highly loaded main girder reaches a maximum bending moment of 8.9423 MN.m and a maximum shear force of 1.3176 MN at the ultimate limit state (ULS). The design leads to the adoption of four 12T15 prestressing tendons and a minimum required prestressing force of 7.07 MN. The verification results show that the maximum stresses in the concrete, prestressing steel, and passive reinforcement remain below the adopted limits. The analysis of time-dependent effects further indicates a final creep coefficient of 1.8549 and a shrinkage strain of −2.7539 × 10⁻⁴. These results show that the combined consideration of traffic actions, prestressing, and time-dependent phenomena provides a more comprehensive characterization of the structural behavior of the bridge deck under the considered design conditions.