Moment-rotation response and punching shear resistance of high performance fiber reinforced cementitious composite structural members.

摘要

High performance fiber reinforced cementitious composites (HPFRCCs) are a class of fiber reinforced cement (FRC) composites that exhibit strain-hardening behavior, accompanied by multiple cracking with small crack widths, when subjected to direct tension. They are known to have very good ductility and high energy absorption capacity in comparison to plain concrete. However, little is known about the moment-rotation response of reinforced concrete beams and the punching shear capacity of concrete slabs using HPFRCCs. Such information is needed to support the implementation in the field of a new bridge deck system, documented in a prior investigation, in which most of the primary conventional reinforcement is replaced by fibers.; To evaluate the moment-rotation response of HPFRCC flexural members, twelve simply supported HPFRCC beams were tested to failure. The parameters included reinforcement configuration (negative and positive moment), type of reinforcement (steel and carbon fiber reinforced polymer), prestressing method of reinforcement (prestressing and non-prestressing), and type of fibers (Spectra and Torex). Test and analysis results showed that HPFRCC beams can achieve rotations up to ten times those of conventional reinforced concrete beams while maintaining adequate moment capacity. The moment-rotation curves obtained from tests were compared with curves predicted using a section nonlinear analysis and found to be in good agreement.; To evaluate punching shear resistance, nine HPFRCC square slabs and one conventional reinforced concrete slab, simply supported along their edges, were tested under monotonic concentric loading. Parameters included reinforcement configuration (reinforcement layers and direction), and fiber type (Spectra, Torex, and PVA). Test results showed that the use of HPFRCC materials led to up to a 100% increase in punching shear resistance and up to a 280% increase in energy absorption capacity in comparison to conventional RC slabs. Based on the results obtained, a punching shear resistance of 1.75 times that assumed in the ACI Code is recommended for design of HPFRCC slabs.