The research concentrated on a behavior of the deep composite deck ComFlor210 under a concentrated force. The distribution of a concentrated force in ComFlor210 was studied numerically and analytically. The finite element model of a composite slab with 5.4m span showed good agreement with test results in the elastic stage. The parametric study of composite slab ComFlor210 revealed that in a slab with span 3.2m and 5.4m the load is distributed over three middle ribs. In a slab with 7.2m span, the load was spread over all five ribs. The bending resistance of the rib was exceeded for slab with 7.2m span. In the elastic part of the load-deflection curve, the variation in cross-sectional properties causes a minor change in a slab response. The proposed engineering model was unable to predict the deflection of the composite slab under concentrated load with the desired accuracy.