Tests on Concrete Slabs Under Hard Missile Impact to Evaluate the Influence of Transverse Reinforcement and Pre-Stressing on Perforation Capacity

Abstract of the technical paper presented at:
21st International Conference on Structural Mechanics in Reactor Technology (SMiRT-21)
New Delhi, India
November 6 - 11, 2011 

Prepared by:
Nebojsa Orbovic, Andrei Blahoianu
Canadian Nuclear Safety Commission
Ottawa, Ontario, Canada  

Abstract

Empirical formulae are used to determine or to check the required thickness of concrete elements to prevent perforation. These empirical formulae for perforation of reinforced concrete elements (slabs) are established for the elements with longitudinal reinforcement only. The influence of transverse reinforcement and pre-stressing is not taken into account.

A series of tests has been carried out on concrete slabs impacted by a hard missile in the velocity range of 100m/s-150m/s at VTT facility in Espoo, Finland. The concrete slabs are with dimensions 2.1m*2.1m*0.25m with transverse reinforcement in form of T-headed bars and with pre-stressing, separated and combined. The most representative results are presented in this paper.

The goal of the tests is to evaluate the behaviour and possible benefits of T-headed bars and pre-stressing on perforation capacity of concrete elements (slabs) under hard missile impact loading. The results are compared to the tests carried out on the similar slabs using longitudinal reinforcement only as well as to the elements with the same reinforcement but with different impact velocity. The behaviour of the concrete slabs, their failure mode and the damage as well as the repeatability of the tests are evaluated as a function of missile velocity.

The conclusion is that the transverse reinforcement combined with T-headed bars can improve significantly the perforation capacity of concrete slabs under hard missile impact.

The ultimate goal is to come up with modified formula which will take into account transverse reinforcement and pre-stressing for the estimation of perforation capacity of concrete elements (slabs). The tests carried out in this campaign are one step towards this goal.

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