The SHEAR BEHAVIOR OF REINFORCED CONCRETE BEAMS STRENGTHENED BY CFRP STRIPS

Istrazivanja i projektovanja za privredu ◽

10.5937/jaes0-29968 ◽

2021 ◽

pp. 1-9

Author(s):

Lubna Mohammed Abd

Keyword(s):

Reinforced Concrete ◽

Shear Failure ◽

Concrete Beams ◽

Reinforced Concrete Beams ◽

Experimental Program ◽

Transverse Reinforcement ◽

Maximum Deflection ◽

Modes Of Failure ◽

Different Shapes ◽

Combined Failure

In this research, (12) normal reinforced concrete beams are used with dimensions (110*10*20) cm, the compressive strength for all specimens is 30 MPa. Longitudinal steel is deformed bars 2Ø12mm with Ø6 mm transverse reinforcement which is deformed bars also for different spacing 5 cm, 10 cm and 15 cm. After casting the specimens and removing them from the molds, they left for about 28 days. They tied by CFRP strips with different shapes of tying (tied, inclined and X- shaped). They are all testing with two points load by a hydraulic machine for determining (Pu, P cr, maximum deflection and modes of failure) and compared among their results with the specimens without CFRP strips. From the experimental program, the excellent behavior of the specimens with the X-shaped strips especially with the Pu which is 70% increment and maximum deflection is 39% decrement. The addition of CFRP strips as a tying material helps to increase the strength of concrete and bearing against loads also, changes and decreases the flexural and shear failure and combined failure.

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Experimental investigation of Low velocity impact response of reinforced concrete beams without stirrups

EPJ Web of Conferences ◽

10.1051/epjconf/201818302038 ◽

2018 ◽

Vol 183 ◽

pp. 02038

Author(s):

Yingqian Fu ◽

Xinlu Yu ◽

Xinlong Dong ◽

Fenghua Zhou

Keyword(s):

Reinforced Concrete ◽

Impact Loading ◽

Concrete Beam ◽

Shear Failure ◽

Concrete Beams ◽

Reinforced Concrete Beams ◽

Low Velocity Impact ◽

Experimental Program ◽

Failure Model ◽

The Impact

This paper presents an experimental program of reinforced concrete beam without stirrups tested by impact three-point-bending under different initial velocity (drop height). As the results shown, for the static events, the failure mode is bending firstly, and then translates to shearing. the longitudinal reinforcements play an important role for the increasing of loading during bending stage. For the impact events, reinforced concrete beams failed in a flexural failure model at slow rates of loading and in shear failure model at high impact loading rate relatively. Moreover, the shear failure and bending failure have developed during the peak stage of Force-deflection curves. That is different with the emergence sequence of cracks under static tests. So the mechanical parameters of peak stage should be considered for the resistance of concrete beam under impact loading.

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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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Effect of Plastering Layer on Corrosion Resistances of Reinforced Concrete Beams

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.a1220.109119 ◽

2019 ◽

Vol 9 (1) ◽

pp. 1390-1393

Keyword(s):

Corrosion Resistance ◽

Reinforced Concrete ◽

Concrete Beams ◽

Point Load ◽

Reinforced Concrete Beams ◽

Experimental Program ◽

Structural Elements ◽

Accelerated Corrosion ◽

Total Mass Loss ◽

Load Arrangement

Reinforced concrete structures are subjected to deterioration due to many factors such as corrosion of reinforcing steel. Ultimate strengths of structural elements can be greatly affected by these deteriorating factors. There are numerous methods and techniques used to protect these structural elements. The mortar layer (Plastering) is considered the first defense line against all the deteriorating factors. The main goal of this research is to investigate to what extent the plastering layer can protect reinforced concrete beams against corrosion. The aim of the experimental program is to study the effect of plastering layer on corrosion resistance of reinforced concrete beams. Four reinforced concrete beams (1002001100 mms) and four Lollypop specimens (cylinders 100200 mms) were tested and described as follows: • A beam and a lollypop specimen without any plastering layer (control). • A beam and a lollypop specimen with traditional plastering layer (cement + sand + water). • A beam and a lollypop specimen with modified plastering (traditional plastering + waterproof admixtures). • A beam and a lollypop specimen with painted and modified plastering layer (traditional plastering + waterproof admixtures + external waterproof paint). These eight specimens were subjected to corrosion using accelerated corrosion technique, after that the four beams were tested in flexure under three point load arrangement while the four lollypops were used to calculate the total mass loss due to accelerated corrosion. The test results were used to figure out the effect of plastering layer on corrosion resistance of RC beams.

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