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Streszczenie:
The reasons for increase of research work on plain and fibre reinforced concrete behaviour due to impact are given. Effects of impact on concrete slabs are described. An original experiment on fibre reinforced concrete slabs of different thicknesses and of different steel content is presented. The slabs were loaded by hard missiles falling down from a constant height. Observed failure modes of slabs, i.e. surface crack pattern and local damage forms until perforation are described. A theoretical analysis of observed failure modes leads to the proposed formula for perforation thickness, well fitting to experimental results. The scope of further investigation is outlined

Słowa kluczowe:
fibre concrete, impact resistance, failure mode, prediction of perforation thickness

Streszczenie:
The paper presents results of impact tests on steel fibre reinforced concrete slabs and an attempt of theoretical analysis of observed phenomena. The influence of fibre
content, slab thickness and impact energy upon the structural performance of slabs was investigated. An observed failure pattern involved the formation and movement of cone shaped plug of material. The number and the width of cracks in slabs were found to be fibre content sensitive. An increase of fibre content from 0.5% to l.0% by volume resulted in an increase of 1.3 to 1.8 times in the number of impacts to failure. Presented attempt of theoretical analysis was based on energy considerations . A simplified model of fracture mechanism provided an expression for the perforation thickness of SFRC slabs that well fitted the test results.

Słowa kluczowe:
fibre concrete, fracture model, impact load, perforation thickress