Load-carrying capacity of steel fiber reinforced concrete beams at large deflections

摘要

Discrete steel fibers are known to control crack widening in concrete members thereby enabling them to carry loads up to large deflections. This study examined the flexural behavior of steel fiber reinforced concrete (SFRC) beams reinforced with steel fibers by conducting four-point bending tests on eight beam specimens. The effect of reinforcing index (defined as the product of the volume fraction and the aspect ratio of steel fibers), fiber type, and beam depth was investigated. The load-carrying capacity corresponding to different beam deflections was predicted using available constitutive stress-strain/crack width laws in tension. Although existing constitutive relations in tension predict the peak load capacity well, they fail to accurately predict the load-carrying capacity at large deflections. Subsequently, a constitutive law is proposed using a back-calculation technique which was validated with the results from four-point bending tests conducted on 24 SFRC beams including 16 results found in the literature. The deviation of the predictions of the proposed model with regard to the average load-carrying capacity at large deflections is within 12% from the observed values.