High performance concrete beams subjected to shock waves from air blast

Authors:

  • Magnusson Johan
  • Hallgren Mikael

Publish date: 2001-03-27

Report number: FOA-R--00-01586-311

Pages: 86

Written in: English

Abstract

This investigation involves testing of reinforced concrete beams of both normal strength concrete (NSC) and high strength concrete (HSC). A total of 33 beams were tested, of which 26 were subjected to shock wave loading from air blast. The different concrete grades used were of compressive cube strength 40, 100, 150 and 200 MPa, respectively. Some beams of highest concrete grade contained steel fibres. Also beams with two concrete layers were tested, i.e. the bottom layer of concrete grade 40 and the top layer of grade 200. The amount of reinforcement was varied in order to study the mechanical properties of beams. Both the load capacity as well as the deflection capacity were studied. In the static tests, the beams were loaded with four point loads. The shock wave tests were performed in a shock tube. The mass of the explosive charge was varied for the different beams and ranged from 1.0 kg up to 7.0 kg. All beams subjected to static loading failed in flexure. In the dynamic tests, the failure mode changed for some beams in relation to the static tests. Beams of concrete grades 40, 100, 150 and 200 without fibres and with high ratio of reinforcement exhibited shear failure. Beams of concrete grades 100 (with a low ratio of reinforcement), 200 containing steel fibres and beams with two concrete layers failed in flexure. A tendency of ultimate concrete strain decreasing with an increasing mechanical ratio of tensile reinforcement was observed. An increase in load capacity for beams subjected to shock waves compared to beams subjected to static loading was also observed.