The structure I am trying to analyze is a 2 cell reinforced concrete box 17 feet below a 6 lane turnpike. The increase in overburden will overstress the RCB, so we are putting 8.5 feet of EPS Geofoam to reduce the stresses on the top slab and side walls.
Can I model the RCB with beams and the Geofoam with a very light material? I am attempting to find the pressures on the walls and top slab using Adonis. See attached drawing.
Thank you in advance!!!!