In the present paper, three dimensional numerical finite element modeling and analyses to evaluate the performance of upgradedexisting masonry arch bridge system isdiscussed. The upgradation of the modified arch-slab bridge system is carried out by introducing reinforced concrete relieving slab over the soil fill. Along with the live load in each case, ballast load and self-weight of the structural components are also considered for the analysis. To avoid any tension between the fill and the arch masonry (both barrel and spandrel), special contact elements with friction co-efficient is incorporated in the finite element model. For masonry arch, William-Warnke model and for soil fill, Drucker-Prager plasticity models are considered to incorporate the nonlinearity in the material. From the numerical simulation studies on the modified arch-slab system for the masonry arch bridge, the proposed upgradation scheme is found to be efficient and adequate to meet the need for broad gauge conversion.

Keywords: Masonry arch bridge, Modified slab-arch system, Stress contours, Nonlinear analysis.