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Description / Abstract:
The design of steel fiber-reinforced concrete (SFRC) slabson-
ground (G-SFRC) and elevated SFRC (E-SFRC) slabs in the past three
decades has resulted in a significant practical and engineering
experience that has not been documented before. This report
addresses various aspects of analysis, design, and construction of
elevated slabs using steel fibers as the primary reinforcement. The
benefits of these systems are discussed in terms of reduction in
the number of joints; shrinkage control enhancement; ductility;
improvements in the architectural design; and reduction of drop
panels and beams, which results in easier forming and setup and,
ultimately, in an economic and sustainable system.
The design procedures address the material and structural
ductility aspects and their effect on the two-way slab mechanism.
Test methods that are applicable to design include the three-point
bending test as a measure of material ductility, and simply
supported round slab as a measure of material and structural
ductility. The discussion of these tests is followed by the
procedures to predict the behavior during full-scale structural
testing. The design guides for strainsoftening,
deflection-hardening materials are also presented as the underlying
basis for these systems.
The structural analysis approach to evaluate the nominal
flexural strength of E-SFRC slabs is based on yield-line theory,
and several cases of uniformly distributed loads, line, and point
load are presented. Flexural strength calculations for failure
patterns can be accomplished using the test data derived from both
the three-point bending flexural test and/ or a test on a
continuously supported round slab. Design examples are presented in
Appendixes A through K in support of the structural analysis
approach and the flexural strength calculations.
Four full-scale tests of elevated slabs are presented and
discussed. Experimental results and model-based computed values are
compared using numerical examples for the verification of the
design. Full-scale testing procedures are presented that show the
ability of deflection hardening SFRC to produce multiple cracks
under flexure and, hence, use of inelastic post-cracking properties
in the design process are discussed.