scholarly journals Impact of Reinforcement Ratio on Shear Behavior of I-Shaped UHPC Beams with and without Fiber Shear Reinforcement

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1525 ◽  
Author(s):  
Altug Yavas ◽  
Cumali Ogun Goker
Keyword(s):  
Shear Strength ◽  
Failure Mode ◽  
High Performance Concrete ◽  
Shear Behavior ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Ultimate Shear Strength ◽  
Loading Test

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.

Influence of synthetic fibers on the shear behavior of lightweight concrete beams

2017 ◽  
Vol 20 (11) ◽  
pp. 1671-1683 ◽  
Author(s):  
Ayman Ababneh ◽  
Rajai Al-Rousan ◽  
Mohammad Alhassan ◽  
Mohammed Alqadami
Keyword(s):  
Shear Strength ◽  
Lightweight Concrete ◽  
Concrete Beams ◽  
Shear Behavior ◽  
Fiber Content ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Ultimate Shear Strength ◽  
Synthetic Fibers

Incorporating discontinuous structural synthetic fibers in general enhances the performance of concrete and increases its durability by minimizing its potential to cracking and providing crack arresting mechanism. Synthetic fibers are non-corrosive, alkali resistant, simple to apply, and added in small quantities due to their low density; thus, a substantial number of uniformly distributed fibers are added. In this research, an experimental program was undertaken to investigate the shear behavior of lightweight concrete beams containing discontinuous structural synthetic fibers. The studied parameters include fiber content and shear reinforcement. The tests were conducted under four-point loading in a simply supported span of 0.85 m. The beams were divided into three groups based on shear reinforcement. Group 1 was designed without shear reinforcement, Group 2 with closed vertical stirrups placed at d/4 spacing (where d is the effective depth), and Group 3 with closed vertical stirrups placed at d/2 spacing. Each group contains four identical specimens except in terms of the fiber content: 0, 3, 5, and 7 kg/m3 equivalent to fiber volume fractions of 0%, 0.33%, 0.55%, and 0.77%, respectively. The experimental results showed that the discontinuous structural synthetic fibers improve the ultimate shear strength, ductility, stiffness, and toughness of lightweight concrete beams significantly. Therefore, design codes are encouraged to consider their contribution to shear strength and revise the maximum stirrups spacing when discontinuous structural synthetic fibers are used. The results also showed that addition of discontinuous structural synthetic fibers reduces the crack width of lightweight reinforced concrete beams. The effectiveness of the discontinuous structural synthetic fibers decreases as the stirrups spacing decreases.

scholarly journals Steel Fiber Use as Shear Reinforcement on I-Shaped UHP-FRC Beams

2019 ◽  
Vol 9 (24) ◽  
pp. 5526 ◽  
Author(s):  
Umut Hasgul ◽  
Altug Yavas ◽  
Tamer Birol ◽  
Kaan Turker
Keyword(s):  
Failure Mode ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Reference Beam ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Shear Reinforcement ◽  
Steel Fiber Reinforced Concrete ◽  
Loading Test

In the presented paper, the effectiveness of steel fiber use on the shear and flexure behaviors of ultra-high performance concrete (UHPC) beams and the feasibility of steel fibers in place of shear reinforcement were investigated experimentally. In this framework, a total of four I-shaped UHPC beams were produced for a high tensile reinforcement ratio of 2.2%. While two of them were non-fiber UHPC beams with and without the shear reinforcement to show the contribution of steel fibers, the remaining beams were made from the ultra-high performance steel fiber-reinforced concrete (UHP-FRC) having the short straight fibers with 1.5% and 2.5% by volume. The shear and flexural parameters, such as the load–deflection response, cracking pattern, failure mode, deflection, and curvature ductilities were discussed based on the four-point loading test results. While the reference beam without fiber and shear reinforcement failed by the shear with a sudden load drop before the yielding of reinforcement and produced no deflection capability, the inclusion of steel fibers to the UHPC matrix transformed the failure mode from shear to flexure through the fibers’ crack-bridging ability. It might be deduced that the moderate level of steel fiber use in the UHP-FRC beams may take the place of shear reinforcement in practical applications.

scholarly journals Experimental analysis of steel fiber reinforced concrete beams in shear

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.

scholarly journals Residual Tensile Stress Estimation for Shear Strength of UHPC Nonprismatic Beams

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nasser Hakeem Tu’ma ◽  
Mustafa Raad Aziz ◽  
Haider Jabbar J. Barry
Keyword(s):  
Shear Strength ◽  
Tensile Stress ◽  
High Performance ◽  
High Performance Concrete ◽  
Longitudinal Axis ◽  
Steel Fibers ◽  
Experimental Program ◽  
Residual Tensile Stress ◽  
Ultra High Performance Concrete ◽  
Failure Patterns

Abstract Estimating the shear strength of Ultra-High-Performance Concrete (UHPC), with high compressive and tensile strengths, is complicated by many variables that affecting its behavior. Residual tensile stress (RTS) plays an important role in raising the efficiency of both types of resistance, especially shear strength due to the presence of steel fibers, which makes it difficult to quantify the residual tensile stress due to the different failure patterns of these fibers and the distribution mechanism within the concrete matrix. There is no study to date in assessing residual tensile stress of UHPC structural members of the variable section. Thirteen beams were selected as an experimental program to study six main variables in determining shear strength. Stirrups ratio, flexural reinforcement ratio, the volumetric fraction of steel fibers, geometry changing, existing openings along the longitudinal axis, and shear span to depth ratio. According to on Tests results, RTS is compatible with most of the global specifications.

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

Buildings ◽  
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.

scholarly journals Experimental Study on Shear Behavior of Reinforced Concrete Sandwich Deep Beam

2020 ◽  
Vol 44 (5) ◽  
pp. 301-309
Author(s):  
Vaka Gopi ◽  
Kagita Kumara Swamy ◽  
Arepalli Peda Gopi ◽  
Vejendla Lakshman Narayana
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Effective Length ◽  
Common Element ◽  
Experimental Program ◽  
Deep Beam ◽  
Shear Reinforcement ◽  
Deep Beams ◽  
Depth Ratio

In present making of construction industry at a high pace. The tendency of world influenced the high raised buildings. In modern days one of the most common element is deep beam, constructed a small span to depth ratio. The transfer girders most of used in deep beams. In an experimental program consists of 12 deep beam specimens are carried out for shear strength behavior investigation of Reinforced Concrete sandwich deep beam concealed with insulation pad in various depths 200mm and 300mm and 400mm. in the experimental program effective length, depth, the width of the specimens, width of bearing plates, longitudinal reinforcement as 1% to maintain constantly and horizontal reinforcement as varies as 0.15% and 0.25% and 0.35%. We are considered shear span to depth ratio of deep beam is 0.95. The main aim of the experimental study the influence of longitudinal shear reinforcement along with vertical and horizontal shear reinforcement on the shear strength, shear ductility of RC sandwich deep beams of insulation pads placed at different depths.

Parametric Analysis of Shear Behavior of Concrete Beams Reinforced with Continuous FRP Rectangular Spirals

2012 ◽  
Vol 217-219 ◽  
pp. 2435-2439
Author(s):  
Ying Tao Li ◽  
Shi Yong Jiang ◽  
Bing Hong Li ◽  
Qian Hua Shi ◽  
Xian Qi Hu
Keyword(s):  
Parametric Analysis ◽  
Failure Modes ◽  
Shear Failure ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Shear Span ◽  
Depth Ratio

An experimental program was carried out by the author to investigate the shear behavior of concrete beams reinforced with continuous FRP rectangular spirals, the main variables considered in the test were the shear reinforcement ratio and the shear span to depth ratio and the longitudinal reinforcement ratio. However, the experimental program is inadequate to gain insight into the shear behavior of the members. First, the quantities of test specimens were too small, only six beams were made and tested, the experimental database was so limited that the resultant analytical results and conclusions may not be sound enough. Second, not all the main factors that have influences on the shear behavior of the members have been treated as variables in the experimental program, such as the effective transverse compression stress and the concrete compression strength, the influences of these two factor on the shear behavior of the members were not clear yet through the experimental study. Considering the insufficient information provided by the experimental investigation, the parametric analysis of the shear behavior of the members was carried out, and a revised rotating-angle softened truss model for the shear analysis of the members was proposed as the analytical tool. Based on the proposed model, the influences of various factors on the shear capacity and shear failure modes of the members were discussed, related nonlinear analysis was carried out using the arithmetic of iteration and step approximation, and several FORTRAN codes were written accordingly. Through the experimental study and the parametric analysis, it is indicated that the shear capacity and the shear failure modes of the members are greatly influenced by three major factors, including the shear reinforcement ratio and the shear span to depth ratio and the effective transverse compression stress. The influences of the concrete compression strength and the longitudinal reinforcement ratio on the shear capacity are not noticeable comparatively. The shear capacity is little affected by the shear span to depth ratio in the case of the shear-tension failure, there is no noticeable correlation between longitudinal reinforcement ratio and the shear failure modes.

scholarly journals Shear strength of brick mortar interface for masonry in Lima city

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Luis Lavado ◽  
Jorge Gallardo
Keyword(s):  
Shear Strength ◽  
Compressive Stress ◽  
Shear Failure ◽  
Pure Shear ◽  
Load Level ◽  
Experimental Program ◽  
Masonry Walls ◽  
Loading Test ◽  
Compression Load ◽  
Building Inventory

Masonry structures constitute a large proportion of the building inventory in Lima and in most cities in Peru, mainly because of their benefits in terms of low cost, good mechanical properties and easily worked. It was observed in the cyclic loading test of masonry walls carried out at CISMID that the modes of failures can be mainly generated by shear forces. Based on the previous information, it is known that diagonal cracking and slip of the mortar-brick joints are the dominant failure mechanisms of confined masonry walls.  In order to determine the mechanical behavior in the mortar-brick joint, an experimental program was carried out, by using industrial and handmade bricks. The test specimens were specifically designed to transmit pure shear along the bed joints under certain constant levels of compressive stress normal to the bed joint. The results of experimental shear tests are presented and discussed. It is then found a consistency between the behavior of masonry joints under shear with the Mohr Coulomb criterion. The shear failure capacity was influenced by the brick type, pre-compression load level and mortar type. It is also noticed in this experimental study that the pre-compressive stress normal to the bed joints significantly increase the shear strength of the mortar-brick joint.

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