Hassan Aoude

Response of Steel Fiber-Reinforced Concrete Beams with and without Stirrups

This paper will discuss how a series of nine full-scale reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) beams were tested to study the effects of steel fibers on shear capacity, failure mechanism, and crack control. Six of the specimens were constructed without shear reinforcement. In addition, three specimens were detailed in accordance with the minimum shear reinforcement requirements of CSA A23.3-04 to examine the influence of fibers on ductility. The results demonstrate that the addition of fibers leads to improved shear resistance in shear-deficient beams. The addition of fibers in beams that contain minimum shear reinforcement results in improved ductility and crack control. A procedure for predicting the shear resistance of SFRC beams is also presented in this paper.

Behavior of Columns Constructed with Fibers and Self-Consolidating Concrete

Steel fiber reinforced concrete was first developed in the 1960s, but the use of this material in load-carrying structural elements has not yet gained wide acceptance. This paper describes a series of 13 full-scale axial compression tests that was conducted on reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) columns. The objectives were to gain a better understanding of the performance enhancements that can be gained from the use of SFRC in columns and to examine if the provision of fibers would permit a reduction of confinement reinforcement. The specimens, which were detailed with varying amounts of transverse reinforcement, were cast using self-consolidating concrete (SCC) that contained various quantities of fibers. The results demonstrate that the addition of fibers leads to improved load-carrying capacity and post-peak response, and greatly delays cover spalling. The findings also show that the addition of steel fibers can partially substitute for the confinement reinforcement in columns, thereby improving constructability while achieving significant confinement. Although an addition of moderate amount of fibers to SCC can result in an adequately workable concrete mixture, there is a limiting fiber content above which the SCC mixture can lose much of its workability.

Response of SFRC Columns under Blast Loads

AbstractResearch has shown that the addition of steel fibers to concrete results in improved postcracking tensile capacity leading to enhanced toughness, ductility, and damage tolerance. These performance enhancements make steel fiber-reinforced concrete (SFRC) an ideal material for use in the blast-resistant design of structures. Research in the literature is conflicting on the performance of SFRC at high strain rates. There is also very limited research on the performance of SFRC structural components under blast loads. This paper presents the results of a research program investigating the blast performance of reinforced concrete and steel fiber-reinforced concrete columns. In the experimental program half-scale columns were constructed and exposed to different simulated blast pressure–impulse combinations using the state-of-the art shock-tube testing facility at the University of Ottawa. The test parameters included transverse reinforcement spacing (nonseismic and seismic detailing) as well as steel f...

Behavior of Rectangular Columns Constructed with SCC and Steel Fibers

AbstractExtensive research has shown that properly detailed and closely spaced transverse reinforcement in reinforced concrete columns can ensure ductile behavior during earthquakes. However, in regions of high seismicity, detailing requirements can result in heavily congested sections; the use of self-consolidating concrete (SCC) can facilitate construction in these situations. Although extensive research exists on the axial load behavior of traditional concrete columns, only limited research exists on the behavior of columns constructed with SCC. Research over the past two decades has also shown that use of steel fiber-reinforced concrete (SFRC) can improve the strength and ductility of columns by delaying cover spalling and improving core confinement. Recent research has also shown that the combined use of SCC and steel fibers can ease problems associated with the workability of traditional fiber-reinforced concrete. This paper presents the results from an experimental program that was conducted to stu...

Effects of Simulated Corrosion and Delamination on Response of Two-Way Slabs

AbstractThis paper presents the results from an experimental program that studied the effects of simulated delamination and corrosion on the structural response of six two-way slab-column specimens with details typical of older construction. The results in terms of load-deflection response, punching shear resistance, and cracking are compared. The test results demonstrate that a reduction in reinforcing bar cross-sectional area (simulated corrosion) leads to a significant drop in punching shear resistance and results in increased crack widths. In addition, the study demonstrates that a critical degree of delamination can lead to a reduction in punching shear capacity, greater crack widths, and loss of stiffness.

Influence of steel fibers on the shear and flexural performance of high-strength concrete beams tested under blast loads

This paper presents the results of a study examining the effect of steel fibres on the blast behaviour of high-strength concrete beams. As part of the study, a series of three large-scale beams built with high-strength concrete and steel fibres are tested under simulated blast loading using the shock-tube testing facility at the University of Ottawa. The specimens include two beams built with conventional high-strength concrete (HSC) and one beam built with high-strength concrete and steel fibres (HSFRC). The effect of steel fibres on the blast behaviour is examined by comparing the failure mode, mid-span displacements and, overall blast resistance of the specimens. The results show that the addition of steel fibres in high-strength concrete beams can prevent shear failure and substitute for shear reinforcement if added in sufficient quantity. Moreover, the use of steel fibres improves flexural response under blast loading by reducing displacements and increasing blast capacity. Finally, the provision of steel fibres is found to improve the fragmentation resistance of high-strength concrete under blast loads.