This study is a part of a larger research program sponsored by the Swedish National Rescue Services Board with the aim to study debris loads of buildings on shelters. One way R. C. slab strips on two or four supports have been loaded statically or impactly by drop weights of steel or concrete. The aim was to determine the energy dissipation to exhaust the bearing capacity of the slabs. The oretical expressions to calculate the energy dissipation were also derived. The reason why the energy dissipation is studied is that it can be shown that a high dissipation leads to a decreased debris load from a building on an underlying shelter. The longterm work is to modify the present formula code for calculating the debris load. The buildings will then be classified into different groups depending on the energy dissipation. This work shows that buildings at least can be divided into two groups. One where the resistance of the slabs depends on flexural moment and one where also membrane effect is provable.