Shear Strength of Prestressed Steel Fiber Concrete I-Beams

This paper presents the fibre-matrix interfacial properties of hooked end steel fibres embedded in ultra-high performance mortars with various water/binder (W/B) ratios. The principle objective was to improve bond behaviour in terms of bond strength by reducing the (W/B) ratio to a minimum. Results show that a decrease in W/B ratio has a significant effect on the bondslip behaviour of both types of 3D fibres, especially when the W/B ratio was reduced from 0.25 to 0.15. Furthermore, the optimization in maximizing pullout load and total pullout work is found to be more prominent for the 3D fibres with a larger diameter than for fibres with a smaller diameter. On the contrary, increasing the embedded length of the 3D fibres did not result in an improvement on the maximum pullout load, but increase in the total pullout work.Keywords: pullout behaviour, bond mechanisms, water/binder ratio, hook geometry, embedment length and fibre-matrix interface.

Section: Introductionmentioning

confidence: 99%

Pull-Out Behaviour of Hooked End Steel Fibres Embedded in Ultra-high Performance Mortar with Various W/B Ratios

Abdallah

Fan

Zhou

2017

“…Basically, with specific revisions, it is applicable to all situations dominated 1) by circulatory torsion, such as high strength concrete members (Bernardo et al 2012b) and box section members (Bernardo et al 2013;Jeng 2015;Wang et al 2015). The softened truss model is also the theoretical model used to simulate the behavior of closed section concrete members under shear (planar softened truss model) (Vecchio and Collins 1981, 1986, 1988Pang and Hsu 1995;Tadepalli et al 2015;Liang et al 2016) as well as under the combined actions of bending, shear and torsion (Rahal and Collins 2003;Rahal 2007;Greene and Belarbi 2009a, b).…”

Section: Introductionmentioning

confidence: 99%

Experimental and Analytical Studies of U-Shaped Thin-Walled RC Beams Under Combined Actions of Torsion, Flexure and Shear

Chen

Guo

et al. 2018

Self Cite

U-shaped thin-walled concrete bridge beams usually suffer the combined actions of flexure, shear and torsion, but no research about the behavior of U-shaped thin-walled RC beams under combined actions has been reported in literature. Three large specimens of U-shaped thin-walled RC beams were tested under different torque-bending moment ratios (T-M ratios) of 1:5, 1:1 and 1:0 to investigate the mechanical responses such as crack patterns, reinforcement strains, failure modes and ductility. The testing results showed that ductile flexural failures occurred for all three of the U-shaped thin-walled beam specimens, although the combined shear effect of circulatory torque, warping torque and shear force increased as the T-M ratio increased from 1:5 via 1:1 to 1:0, reflected by diagonal cracks and stirrup strains. More specifically, basically symmetrical flexural failure was dominated by the bending moment when the T-M ratio was 1:5; flexural failure of the loaded half of the U-shaped thin-walled section was dominated by the combined action of the bending moment and warping moment, while there were only a few cracks on the other half of the U-shaped section when the T-M ratio was 1:1; and anti-symmetrical flexural failure was dominated by the warping moment when the T-M ratio was 1:0 (pure torsion). A simple method to calculate the ultimate load of such U-shaped thin-walled RC beams under different T-M ratios was suggested, and the calculating results were corresponding well with the experimental results.

“…Available information suggests that while there is a nominal increase in flexural strength compared to plain concrete there is a significant increase in toughness (Gopalaratnam et al 1991;Gopalaratnam and Gettu 1995;Armelin and Banthia 1997;Barros and Figueiras 1999;di Prisco et al 2009;ACI 544.1R-96 2006). In SFRC, fibers enhance the postcracking behavior by providing crack bridging stresses and thus ensure stress transfer across the cracked sections (Tadepalli et al 2015;Sorensen et al 2014). Several factors that influence the crack formation and crack growth include, type of fibers, volume of fibers, the distribution and orientation of fibers at the crack location (Gettu et al 2005;Laranjeira et al 2012;Michels et al 2013;Islam and Alam 2013;Abdallah et al 2016;Adjrad et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Crack Propagation and Post-cracking Hinge-type Behavior in the Flexural Response of Steel Fiber Reinforced Concrete

Gali

Subramaniam

2017

An experimental evaluation of crack propagation and post-cracking behavior in steel fiber reinforced concrete (SFRC) beams, using full-field displacements obtained from the digital image correlation technique is presented. Surface displacements and strains during the fracture test of notched SFRC beams with volume fractions (V f ) of steel fibers equal to 0.5 and 0.75% are analyzed. An analysis procedure for determining the crack opening width over the depth of the beam during crack propagation in the flexure test is presented. The crack opening width is established as a function of the crack tip opening displacement and the residual flexural strength of SFRC beams. The softening in the post-peak load response is associated with the rapid surface crack propagation for small increases in crack tip opening displacement. The load recovery in the flexural response of SFRC is associated with a hinge-type behavior in the beam. For the stress gradient produced by flexure, the hinge is established before load recovery is initiated. The resistance provided by the fibers to the opening of the hinge produces the load recovery in the flexural response.