Shear Strength of Sand-Lightweight Concrete Deep Beams with Steel Fibers

In the presented paper, the impacts of steel fiber use and tensile reinforcement ratio on shear behavior of Ultra-High Performance Concrete (UHPC) beams were investigated from the point of different tensile reinforcement ratios. In the scope of the experimental program, a total of eight beams consisting of four reinforcement ratios representing low to high ratios ranged from 0.8% to 2.2% were casted without shear reinforcement and subjected to the four-point loading test. While half of the test beams included 30 mm end-hooked steel fibers (SF-UHPC) with 2.0 vol%, the remaining beams were produced without the fiber to show possible effectiveness of the fiber use. The shear performances were discussed in terms of the load—deflection response, cracking pattern and failure mode, first cracking load and ultimate shear strength. In this sense, all the non-fiber beams were failed by shear with a dramatic load drop, regardless of the tensile reinforcement amount, before the yielding of reinforcement and they produced no deflection capability. The test results showed that while the inclusion of steel fibers to the UHPC mixture with low reinforcement ratios changed the failure mode from the shear to flexure, it significantly enhanced the ultimate shear strength in the case of higher reinforcement ratio through the SF-UHPC’ superior mechanical properties and fibers’ crack-bridging ability.

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Probabilistic shear strength models for reinforced concrete deep beams

Bridge Maintenance, Safety, Management and Life Extension ◽

10.1201/b17063-172 ◽

2014 ◽

pp. 1163-1167

Author(s):

T Wu ◽

X Liu ◽

B Lv ◽

D Frangopol

Keyword(s):

Shear Strength ◽

Reinforced Concrete ◽

Deep Beams ◽

Strength Models

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Shear Behavior of Steel-Fiber-Reinforced Recycled Aggregate Concrete Deep Beams

Buildings ◽

10.3390/buildings11090423 ◽

2021 ◽

Vol 11 (9) ◽

pp. 423

Author(s):

Nancy Kachouh ◽

Tamer El-Maaddawy ◽

Hilal El-Hassan ◽

Bilal El-Ariss

Keyword(s):

Shear Behavior ◽

Shear Capacity ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Steel Fibers ◽

Recycled Aggregate ◽

Shear Reinforcement ◽

Deep Beams ◽

Control Beam ◽

Shear Response

Results of an experimental investigation aimed at studying the effect of steel fibers on the shear behavior of concrete deep beams made with a 100% recycled concrete aggregate (RCA) are presented in this paper. The study comprised testing of seven concrete deep beam specimens with a shear span-to-depth ratio (a/h) of 1.6. Two beams were made of natural aggregates (NAs) without steel fibers, two beams were made of a 100% RCA without steel fibers, and three beams were made of RCA-based concrete with steel fibers at volume fractions (vf) of 1, 2, and 3%. Two of the beams without steel fibers included a minimum shear reinforcement. Test results showed that the beam with a 100% RCA without steel fibers exhibited a lower post-cracking stiffness, reduced shear cracking load, and lower shear capacity than those of the NA-based control beam. The detrimental effect of the RCA on the shear response was less pronounced in the presence of the minimum shear reinforcement. The addition of steel fibers significantly improved the shear response of the RCA-based beams. The post-cracking stiffness of the RCA-based concrete beams with steel fibers coincided with that of a similar beam without fibers containing the minimum shear reinforcement. The use of steel fibers in RCA beams at vf of 1 and 2% restored 80 and 90% of the shear capacity, respectively, of a similar beam with the minimum shear reinforcement. The response of the RCA specimen with vf of 3% outperformed that of the NA-based control beam with the minimum shear reinforcement, indicating that steel fibers can be used in RCA deep beams as a substitution to the minimum shear reinforcement. The shear capacities obtained from the tests were compared with predictions of published analytical models.

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Experimental analysis of steel fiber reinforced concrete beams in shear

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952022000300001 ◽

2022 ◽

Vol 15 (3) ◽

Author(s):

Aaron Kadima Lukanu Lwa Nzambi ◽

Dênio Ramam Carvalho de Oliveira ◽

Marcus Vinicius dos Santos Monteiro ◽

Luiz Felipe Albuquerque da Silva

Keyword(s):

Shear Strength ◽

Reinforced Concrete ◽

Steel Fiber ◽

Concrete Beams ◽

Reinforcement Ratio ◽

Steel Fibers ◽

Reinforced Concrete Beams ◽

Experimental Program ◽

Longitudinal Reinforcement ◽

Fiber Addition

Abstract Some normative recommendations are conservative in relation to the shear strength of reinforced concrete beams, not directly considering the longitudinal reinforcement rate. An experimental program containing 8 beams of (100 x 250) mm2 and a length of 1,200 mm was carried out. The concrete compression strength was 20 MPa with and without 1.00% of steel fiber addition, without stirrups and varying the longitudinal reinforcement ratio. Comparisons between experimental failure loads and main design codes estimates were assessed. The results showed that the increase of the longitudinal reinforcement ratio from 0.87% to 2.14% in beams without steel fiber led to an improvement of 59% in shear strength caused by the dowel effect, while the corresponding improvement was of only 22% in fibered concrete beams. A maximum gain of 109% in shear strength was observed with the addition of 1% of steel fibers comparing beams with the same longitudinal reinforcement ratio (1.2%). A significant amount of shear strength was provided by the inclusion of the steel fibers and allowed controlling the propagation of cracks by the effect of stress transfer bridges, transforming the brittle shear mechanism into a ductile flexural one. From this, it is clear the shear benefit of the steel fiber addition when associated to the longitudinal reinforcement and optimal values for this relationship would improve results.

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The shear strength of shear walls

Bulletin of the New Zealand Society for Earthquake Engineering ◽

10.5459/bnzsee.3.4.148-162 ◽

1970 ◽

Vol 3 (4) ◽

pp. 148-162

Author(s):

T. Paulay

Keyword(s):

Shear Strength ◽

Reinforced Concrete ◽

Concrete Beams ◽

Shear Walls ◽

Shear Wall ◽

Reinforced Concrete Beams ◽

Research Projects ◽

Deep Beams ◽

Current Recommendation ◽

The University

To enable a comparison between the shear strength of shear walls and that of reinforced concrete beams to be made, the behaviour of the latter is briefly reviewed. The findings of research projects, related to deep beams and the effects of repeated cyclic loading, are summarised. More detailed information on the shear strength of deep beams, tested at the University of Canterbury, is presented, Particular problems associated with four classes of typical shear walls of multi-storey structures are briefly highlighted. The current recommendation of the  SEAOC code, as applied to shear walls, are critically examined and certain anomalies, which may ensue from their interpretation, are illustrated. Areas of research, related to the full evaluation of reinforced concrete shear wall  behaviour, are suggested. The paper concludes with a number of design recommendations which suggest themselves from this review.

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