Advanced Nonlinear Finite Element Modelling of Reinforced Concrete Bridge Piers

Severe cracking was observed on the flexural tension face of a reinforced concrete hammerhead bridge pier cap. Determining the cause and severity of the damage was complicated by the geometry of the piers, which influenced the strut-and-tie mechanism. A tapered end cap raised questions about the development of the tension reinforcement in the chord, while a hexagonal pier column meant that the effective area of the compressive strut was uncertain. Depending on the assumptions made, widely different estimates of the ultimate capacity were reached by traditional calculation methods. Therefore, to accurately assess the safety of the bridge piers, a series of analyses were performed using VecTor2 - a nonlinear finite element analysis program (NLFEA) developed at the University of Toronto. A parametric study was conducted by varying the effective width of the piers and the amount of reinforcement engaged, and the factored strength of the pier was obtained using a novel procedure. This paper concludes that using 2-D NLFEA in a discerning manner allows engineers to understand complex 3-D situations.