Finite-Element Modeling of Reinforced Concrete Arch Under Live Load

Full-scale field tests were conducted on two 8.5-m (28-ft) span reinforced concrete arch culverts. The culverts were subjected to service live loads at depths of cover from 0.3 to 0.9 m (1 to 3 ft). At I ft of fill, the culverts were loaded with a simulated single-axle live load greater than 980 kN (220,000 lb). Field data collected included arch deflection, interface pressure, concrete strain, and reinforcing strain. The computer modeling of the live-load tests is reported. Two- and three-dimensional finite-element analyses were conducted. Nonlinear material models were used for the backfill soil and the reinforced concrete in both the two- and three-dimensional analyses. Results from the finite-element analyses are compared with the field test data. Results of this study indicate that the two-dimensional models are limited in their ability to predict the longitudinal spreading of live load forces in the culverts and to predict maximum moments larger than those in the actual structure. The three-dimensional finite-element deflection predictions were dependent on the properties used to define the concrete material model; however, the design forces (moment, thrust, and shear) did not show the same sensitivity. This indicates that for typical structural design, material parameters may be approximated without seriously degrading the accuracy of predicted design forces. The test structures met AASHTO design criteria for strength and serviceability.