Development of design guidance for low velocity impacts on concrete floors

It has been recognised in the UK, that where designers or safety assessors have to consider the effects of dropped loads on various targets, there is uncertainty associated with the fact that these are low velocity impacts. This uncertainty arises for a variety of load/target combinations, but in this paper we concern ourselves with loads which are massive and with reinforced concrete floor targets. The major uncertainty for dropped load assessments, lies in the fact that the designer does not have access, in general, to relevant data. Instead, it is usual, for design purposes, to make use of empirical formulae which are intended for high velocity missiles. The design process involves using the empirical formulae not only for the local damage which they are intended to address, but also to define a load-time history or impulse for the purposes of determining slab response. This paper indicates the range of events that need to be considered, the manner in which the designer approaches the task of making his assessment of the target and the limits of applicability of the available empirical methods. The programme now in progress in the UK is outlined and some of the results emerging are presented.