Soil-structure interaction for integral bridges and culverts

Abstract

A thorough state of the art on the soil-structure-interaction issues of integral bridges and culverts is provided, focusing on the earth pressure behind integral-bridge abutments. The procedure of the Swedish design code for estimating the earth pressure response to integral bridge abutment movement is found to be conservative compared to the one of the British code and to some recent experimental studies. The influence of soil stiffness and different ways of acquiring this parameter are discussed. Upon comparison of several methods for the determination of the elasticity modulus of soil, it can be concluded that the E s values of Duncan et al.'s SCI method are much more conservative than the E t values by Duncan et al.'s hyperbolic equation and Pettersson et al.'s Method 2. Also, there are significant differences between that Method 2 and Lehane et al.'s and Lade et al.'s methods. The results of the bending moment calculations done on three culverts with different height-to-span ratios suggest that live-load moments are very sensitive to the stiffness of the backfill soil. The bending moments due to live loads are also sensitive to cover depths. For low covers, the moments are much more sensitive to changes in cover depth. This demonstrates how and when arching effects actually take place. The moment calculations for a typical slab-frame bridge reveal that the moments at the abutment front are reduced significantly as the soil stiffness changes from very low to high. The effect of change of the parameter in the passive soil-response formula of the Swedish bridge design code on moments is also significant.