Abstract A formulation is presented for obtaining the optimum floorplan topology that minimizes the damaging effects of deflections due to mobile live loads. A live load damage index, composed of frequencies and path lengths of live loads as well as the maximum deflections, serves as the objective function. Mixing of the sizing and topology variables and the required transformation of the floorplan topology into an analysis model pose the major difficulty in the implementation of the proposed formulation. The difficulty is resolved by excluding the sizing variables from the formulation and by using the proportionality between loads and deflections so that the deflections are eliminated from the formulation and thus the analysis is completely bypassed. The reduced optimization problem can then be readily solved by using one of the available computer programs for ‘building block layout’ optimization.