A STRENGTH BASED ANALYSIS OF RECOMMENDED DOSAGERATES FOR A SPECIFIC SYNTHETIC STRUCTURAL FIBER USED TOREPLACE STEEL IN SLAB ON GRADE CONSTRUCTION

摘要

It is well recognized that the addition of fibers improves concrete properties includingductility, fracture toughness and crack control.The use of structural synthetic fibers as a replacement for continuous steel reinforcement in slab-ongroundis becoming more accepted and widely used. It is however, important to ensure that the level ofreinforcement offered by the structural synthetic fibers is in fact equivalent to that of the steelreinforcement that is being replaced.This presentation addresses a strength based analysis and the calculation of recommended dosage ratesfor a specific structural synthetic fiber to match the level of reinforcement provided by various types ofwelded wire mesh and light rebar.The improvement of the residual strength or post cracking strength of fiber reinforced concrete ispresented as the equivalent flexural strength, feg, which was initially developed by the Japanese ConcreteInstitute (JCI-SF4). ASTM 1399, ASTM C1018, JCI-SF4 and RILEM TC-162 determine the post-crackingstrength or residual strength of fiber reinforced concrete assuming a linear elastic behavior. This impliesthat post-cracking strength of fiber reinforced concrete can be easily calculated using the equivalentflexural strength from the bending tests specified in standard tests.The equivalent flexural strength is a strength parameter that characterizes the post-cracking resistance.Therefore, it can be used for design and stress analysis of fiber reinforced concrete structures.The equivalent flexural strength (of a fiber reinforced concrete section) can then be calculated to matchthe required level of performance of a given level of reinforcement provided by welded wire mesh or lightrebar. Having calculated the equivalent flexural strength, the fiber dosage rate is determined to producethe required level of post-cracking strength for the concrete class under consideration.