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Accession Number PB2012-114858
Title Development of a Failure Theory for Concrete.
Publication Date Aug 2012
Media Count 178p
Personal Author M. Roddenberry R. Kampmann W. C. V. Ping
Abstract The failure behavior of concrete materials is not completely understood because conventional test methods fail to assess the material response independent of the sample size and shape. To study the influence of strength affecting test conditions, four typical concrete sample types were experimentally evaluated in uniaxial compression and analyzed for strength, crack initiation/propagation, and fracture patterns under varying boundary conditions. Both low friction and conventional compression interfaces were assessed. High-speed video technology was used to monitor macrocracking. Inferential data analysis proved reliably lower strength results for reduced surface friction at the compression interfaces, regardless of sample shape. Reciprocal comparisons revealed statistically significant strength differences between most sample shapes. Crack initiation and propagation was found to differ for dissimilar compression interfaces. The principal stress and strain distributions were analyzed, and the strain domain was found to resemble the experimental results, whereas the stress analysis failed to explain failure for reduced end confinement. Neither stresses nor strains indicated strength reductions due to reduced friction, and therefore, buckling was considered. The high-speed video analysis revealed buckling phenomena, regardless of end confinement. Slender elements were the result of low friction, and stocky fragments developed under conventional confinement. The critical buckling load increased accordingly. The research showed that current test methods do not reflect the 'true' compressive strength and that concrete failure is strain driven. Ultimate collapse results from buckling preceded by unstable cracking.
Keywords Compression
Concrete
Crack
Failure theory
Fracture
High-speed video

 
Source Agency Department of Transportation Research and Special Programs Administration
NTIS Subject Category 89G - Construction Materials, Components, & Equipment
50C - Construction Equipment, Materials, & Supplies
Corporate Author Florida State Univ., Tallahassee. Coll. of Engineering.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1226
Contract Number N/A

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