Top PDF Experimental Study on Shear Strengthening of RC Deep Beams with Large Openings Using CFRP

Experimental Study on Shear Strengthening of RC Deep Beams with Large Openings Using CFRP

Experimental Study on Shear Strengthening of RC Deep Beams with Large Openings Using CFRP

Abstract: This research deals with the experimental study on the behaviour of reinforced concrete (RC) deep beams with large circular openings and openings strengthened using externally bonded Carbon Fiber Reinforced Polymer (CFRP) composites in shear. The structural behavior including the load deflection behaviour, crack pattern, failure mode as well as strengthening configuration was investigated. A total of three (3) specimens of beams with design strength of 35 MPa were tested to failure under 4-points loading. The beam specimens included a solid RC deep beam as a control beam and two RC deep beams with large circular openings to determine the behaviour of un-strengthened and strengthened beams using CFRP wrap. The beams had a cross section of 120 mm x 600 mm and a length of 2400 mm. The openings were placed at the support on both sides of the shear span, at a distance 300 mm from the edge of the beam. The circular opening was designed to a standard of 0.45h which is considered as large circular opening with a diameter of 270 mm. Shear span-to-depth ratio (a/h) was 0.83 in which the distance between the loading point and the support was 500 mm. One of the test parameters presented in this paper was surface strengthening method. RC deep beam with the presence of large circular openings in the shear zone experienced substantial strength loss with a reduction of 51% as compared to the original structural capacity of the control beam. Comparing with the control beam, surface strengthening method could only manage to re-gain the beam capacity up to 56%.
Show more

7 Read more

Review  on Shear Strengthening of Rc Deep Beams with Openings

Review  on Shear Strengthening of Rc Deep Beams with Openings

Fadzil et al.(2015) worked on “ Experimental Study on Shear Strengthening of RC Deep Beams with Large Openings Using CFRP”. The work was done to experimentally study the behavior of reinforced concrete (RC) deep beams with large circular openings and openings strengthened using externally bonded Carbon Fiber Reinforced Polymer (CFRP) composites in shear. To investigate the structural behavior including the load deflection behavior, crack pattern, failure mode as well as strengthening configuration. One of the test parameters presented in this paper was surface strengthening method. A total of three (3) RC deep beams were considered in this study. The beams include a solid beam as the reference beam while the remaining beams were with openings located at the middle of the shear span. All the beams had a cross-section of 120 mm x 600 mm and a length of 2400 mm. It was concluded that the RC deep beam with large circular opening experienced substantial strength loss with a reduction of 51% as compared to the beam capacity of the control beam. Surface strengthening using CFRP wrap around the opening could increase the ultimate load capacity, about 15.32% as compared to the un- strengthened beam. Comparing with the reference beam, this strengthening method could only re-gain the beam capacity up to 56%.
Show more

5 Read more

An Experimental Study on Shear Strengthening of RC Lightweight Deep Beams Using CFRP

An Experimental Study on Shear Strengthening of RC Lightweight Deep Beams Using CFRP

practice is empirical or semi-empirical. The shear behavior of RC beams depends on the size of the specimen, reinforcement type and detailing as well as the type and position of applied loading. Besides the concrete shear resistance capacity, additional contributions come from external and/or internal reinforcements of a RC beam specimen. Provided reinforcements help in improving the failure nature, brittle to ductile, to some extent. External shear strengthening using FRP composites gained popularity over steel because of several reasons including material cost, lightweight feature and ease of application. Moreover FRP has more reliable bond line strength as compared to steel where corrosion at the interfaces unavoidable in the presence of moisture [1]. Numerous studies reported a remarkable increase in the shear strength of shallow RC beams when strengthened with externally bonded FRP system [2-4]. Triantafillou reported that the gain in shear strength caused by FRP was primarily dependent on the number of FRP layers and the amount of internal shear steel reinforcement. The FRP shear strengthening system was found more effective when the fibers were oriented in a direction perpendicular to the potential diagonal shear cracks. Deniaud and Cheng presented a review summary of several shear design methods for reinforced concrete beams strengthened with composites Very few researchers investigated the effective of externally bonded FRP system as an external reinforcement to strengthening RC deep beams [5-7]. Zhang and Moren reported that the contribution of the externally bonded FRP system to the shear strength decreased as the shear span-to-depth ratio was reduced. Vertical FRP shear strengthening resulted in a 79% increase in the shear strength at a shear span-to-effective depth ratio of 1.875
Show more

11 Read more

Numerical Study on FRP Strengthened RC Deep Beams with Openings

Numerical Study on FRP Strengthened RC Deep Beams with Openings

The study conducted by Tamar El Maaddawy et.al [1] reported that the use of externally bonded carbon fiber polymer composite sheets was found to be very effective in upgrading the shear strength of RC deep beams. The strength gain caused by the CFRP sheets was in the range of 35% - 73%. Qudeer Hussain et.al [2] conducted an experimental study on Shear strengthening of RC deep beams with openings using sprayed glass fiber reinforced polymer composites. Mechanical anchors were used to prevent the de-bonding of FRP from the beam surface. From the studies, it was reported that the use of mechanical anchors were effective in preventing the de-bonding failure thereby increasing the ultimate load carrying capacity of the deep beams. M. R Islam et.al [3] reported that the use of FRP systems leads to a much slower growth of the critical diagonal cracks and enhances the load carrying capacity of the beam to a level quite sufficient to meet most of the practical upgrade requirements.
Show more

9 Read more

Behavior of FRP-Strengthened RC Beams with Large Rectangular Web Openings in Flexure Zones: Experimental and Numerical Study

Behavior of FRP-Strengthened RC Beams with Large Rectangular Web Openings in Flexure Zones: Experimental and Numerical Study

The strengthening schemes were designed once the flexural tests for the unstrengthened specimens with and without openings were done and the failure patterns established. As mentioned earlier, two different schemes were designed in this study. The first scheme (scheme-1) involved the use of CFRP laminates and the second scheme (scheme-2) involved the use of GFRP laminates anchored using steel plates. Details of beam strengthened with scheme-1 (BS1-O1-CPL) are given in Fig. 4. In addi- tion, steps involved in strengthening of beam BS1-O1- CPL using scheme-1 are depicted in Fig.  5. As shown in Figs. 4 and 5, the first scheme comprised of applying two layers of CFRP sheets in the designated patterns. CFRP strips of 112.5  mm width were applied to the bottom and top chords of the beam first, with the primary fib- ers oriented longitudinally. The length of these strips was 900 mm, as shown in Fig. 4a. The strips were applied on both sides of RC beams. On top of these strips, the sec- ond layer of CFRP was applied with the pattern shown in Fig. 4b. The second layer comprised of four pieces of CFRP sheets with fibers oriented vertically, which were applied separately to the top and bottom chords, and on both sides of the opening. It should be noted that the chord above the opening and the two sides were wrapped using a U-shape wrap; whereas, the chord below the opening was fully wrapped. The reason for this being that practically it would not be possible to wrap the top chord fully due to the presence of slab on top of the beam.
Show more

28 Read more

Study on Shear Strengthening of RC Continuous Beams with Different CFRP Wrapping Schemes

Study on Shear Strengthening of RC Continuous Beams with Different CFRP Wrapping Schemes

Deterioration of concrete structures is one of the major problems of the construction industry today. Moreover, a large number of structures constructed in the past using the older design codes in different parts of the world are structurally unsafe according to today design codes [1]. Shear failure of RC beams, caused by their brittle nature, has been identified as the most disastrous failure mode, it occurred with no advance warning of distress. Shear deficiency may occur due to many factors such as insufficient shear reinforcement or reduction in steel area due to corrosion, increased service load and construction errors [2]. Bonding plates to the external surface of existing reinforced concrete elements have proved to be an effective and practical means of increasing strength and stiffness [3]. The use of externally bonded fiber reinforced polymer (FRP) reinforcement to strength reinforced concrete structures is becoming an increasingly popular retrofit technique. FRP is a composite material generally consisting of carbon, aramid or glass fibers in polymeric matrix [4]. This research focused on using Carbon Fiber Reinforced Polymer (CFRP) systems consisting of flexible sheets. The objective of this study were to investigate the effectiveness of using externally bonded CFRP strips in repair and strengthen of reinforced concrete continuous beams.
Show more

8 Read more

Comparative Study on Torsional Strengthening of RC Beams using CFRP and BFRP Wrapping

Comparative Study on Torsional Strengthening of RC Beams using CFRP and BFRP Wrapping

Although these methods will continue to be used in many more instances, fibre reinforced polymer (FRP) composites provide another option for strengthening. These composites can be three to five times stronger, two to three times stiffer and three to four times lighter than metals such as steel and aluminium. In addition, composites are dimensionally stable, aesthetically pleasing and cost effective with better durability and lower maintenance than the conventional materials. FRP composites have shown great promise in flexural and shear strengthening as external reinforcement. Little attention has only been paid to its applicability in torsional strengthening of RC beams in terms of both experimental and numerical research. This is due to the specialized nature of the problem and the difficulties in conducting realistic tests of torsion and representative analyses.
Show more

7 Read more

Analytical Study on the Effects of Creating Circular Openings in RC Beams and Strengthening with CFRP Sheets and BFRP Sheets

Analytical Study on the Effects of Creating Circular Openings in RC Beams and Strengthening with CFRP Sheets and BFRP Sheets

In this study a three-dimensional nonlinear finite element method using ANSYS 15.0, is used to analyse beams with circular openings. The presence of openings in RC beams is frequently required to accommodate essential services such as ventilating and air conditioning ducts telephone lines. Provision of such openings due to architectural or mechanical requirements would reduce the element’s capacity, thus rendering a severe safety hazard. Thus adequate measures should be taken to strengthen the beam and counteract the strength reduction. This paper, influence the use of Carbon fibre reinforced polymer (CFRP) and Basalt fibre reinforced polymer (BFRP) on increasing the strength of concrete beams having circular opening. A total of nine beams were modeled. In this three beams were modeled as control beam, i.e. one beam without opening (i.e. solid beam), and two beams with circular shear and flexural opening. The remaining six beams were externally strengthened by Carbon fibre reinforced polymer (CFRP) and Basalt fibre reinforced polymer (BFRP) sheets with different strengthening techniques i.e. around the opening, inside the opening, inside and around the opening. The effect of CFRP and BFRP sheet with different strengthening techniques were studied in terms of cracking pattern, ultimate failure load, ductility, and deflection.
Show more

8 Read more

Experimental Study on Strengthening of Openings in R.C Beams using BFRP Fabric

Experimental Study on Strengthening of Openings in R.C Beams using BFRP Fabric

and tie model approach both experimentally and analytically and concluded that ultimate load obtained from the finite element software has only 5% variation compared to experimental. Khaled Fawzy, Mahmoud M. Hashem [12] studied the strengthening effect of different schemes of CFRP sheets on the behaviour of RC beams with large web opening under pure torsion and concluded that CFRP sheets increased the stability of beam.Mithun Kumar, Shivaraj Mangalagi, et al [1] studied the behaviour of RCC Beam with circular opening Strengthened by CFRP and GFRP sheets around and inside openings and it was found that ultimate load carrying capacity increases when it is strengthened.Rakesh Diggikar, Shivaraj Mangalagi et al [2]S.C. Chin, N. Shafiq et al [3] strengthening of RC beams containing large Opening at flexure with CFRP laminates and was found large opening at flexure reduces the beam capacity and stiffness, and increases cracking and deflection.S.C. Chin, N. Shafiq et al [4] studied Reinforced Concrete (RC) beams with large square openings placed in the shear region, at a distance “0.5d” and “d” away from the support, strengthened by Carbon Fiber Reinforced Polymer (CFRP) laminates.Sharda P. Siddh, [5] developed analytical models for calculating the deflections due to uniformly applied transverse loads.Tiago Miguel Cameira Neto [6] provided guidance on determining the design resistance of composite beams with large web openings.Subhajit mondal, Bandyapadhya et al [7] discussed the use of GFRP for strengthenig purpose and its rehabilation.Nageh ,Ali1mohamed et al [8] studied the efficiency of internal strengthening R.C beams with rectangular openings in shear zone by using steel plates. External strengthening by using external steel plates or external CFRP laminates will be a satisfactory method in the case if it is required to provide new opening in existing beams.
Show more

7 Read more

Non-Linear Analysis Of Reinforced Concrete Continuous Deep Beams With Openings Strengthened Using CFRP Sheets

Non-Linear Analysis Of Reinforced Concrete Continuous Deep Beams With Openings Strengthened Using CFRP Sheets

caused a high reduction in the shear capacity of the beams by about 35%. In addition, the strengthening of openings contains the cracks and increase the crack and ultimate load. Finally, they recommended, the openings should be kept away from the load path connecting the loading and support point. If the openings were far from the natural load path, e.g. within the mid-span region, the results indicated that the opening effect becomes minimum. Therefore, these regions are suitable for providing openings when required. In (2017) Al-Mutairee [5] tested sixteen specimens under two-point loading to study the flexural behavior of reinforced concrete continuous deep beams made of normal strength concrete, hybrid concrete, and high strength concrete at different percentage and location and their strengthening by CFRP. The main variables studied were the high strength concrete layer thickness and CFRP on the deep beams strength. The test results showed that the strengthening of continuous deep beams by high strength concrete layer from top was more effective than from bottom. The optimal layer thickness percentage was 25% of the total depth of beams. Also, the strengthening of hybrid continuous deep beams by CFRP strips at bottom for flexural increased the load capacity.
Show more

5 Read more

Analytical and experimental study on repair effectiveness of CFRP sheets for RC beams

Analytical and experimental study on repair effectiveness of CFRP sheets for RC beams

Most research on using FRP plate bonding for flexural strengthening was carried out in the last decade (Ritchie et al. 1991; Saadatmanesh, Ehsani 1991; Triantafillou, Plevris 1992). There has been an explosive growth in the recent years, which resulted from the increasing global need for structural performance updating and retrofitting works. The strengthening and repair of RC structures has become increasingly important, especially in the last decade. Strengthening is usually needed to improve the performance of existing RC structures. A change in the capacity of a structure in service could be due to an increase or change in applied loads, for example, increase in traffic above bridges, addition of extra floors on an existing structure, or installation of new equipment. Many RC structures are damaged mostly due to various forms of deterioration, like cracks or large deflections. These are affected by different factors, such as earthquakes, vibrations, corrosion of reinforced bars and environmental
Show more

8 Read more

Effect of Fiber Orientation on Shear Behavior of RC Beams Externally Strengthened with CFRP

Effect of Fiber Orientation on Shear Behavior of RC Beams Externally Strengthened with CFRP

Abstract Strengthening of reinforced concrete beams with carbon fiber reinforced polymer (CFRP) is one of the recent applied strengthening techniques. It offers an attractive solution to enhance shear and flexural capacities of reinforced concrete (RC) beams. Behavior in shear and flexure of reinforced concrete beams externally strengthened with CFRP is highly influenced by the way in which these composites are bonded to the beam. In this paper reinforced concrete (RC) beams strengthened with CFRP was modelled using a nonlinear finite element (FE) model to study the influence of the orientation layer of CFRP on the overall response of strengthened RC beams in shear. This is carried out to achieve the optimum utilization of such strengthening technique in terms of load bearing capacity and possible deflection values. A nonlinear finite element software ANSYS was utilized in this study. The analysis of the results indicated that the overall behavior of the FE models have a good agreement with corresponding previous experimental results. Further, the parametric study proved that shear strengthening of RC beams with vertical CFRP fabric is more efficient than strengthening with CFRP fabric inclined at an angle of 45°. Furthermore, strengthening the reinforced concrete beams with one layer of U-wrap CFRP fabric inclined at an angle of 45° with an additional horizontal layer of CFRP fabric on both sides of the web is more efficient than strengthening with one layer of U-wrap vertical CFRP fabric with an additional horizontal layer of CFRP fabric on both sides of the web.
Show more

8 Read more

Study on shear strengthening of RC continuous beams with different CFRP wrapping schemes

Study on shear strengthening of RC continuous beams with different CFRP wrapping schemes

Deterioration of concrete structures is one of the major problems of the construction industry today. Moreover, a large number of structures constructed in the past using the older design codes in different parts of the world are structurally unsafe according to today design codes [1]. Shear failure of RC beams, caused by their brittle nature, has been identified as the most disastrous failure mode, it occurred with no advance warning of distress. Shear deficiency may occur due to many factors such as insufficient shear reinforcement or reduction in steel area due to corrosion, increased service load and construction errors [2]. Bonding plates to the external surface of existing reinforced concrete elements have proved to be an effective and practical means of increasing strength and stiffness [3]. The use of externally bonded fiber reinforced polymer (FRP) reinforcement to strength reinforced concrete structures is becoming an increasingly popular retrofit technique. FRP is a composite material generally consisting of carbon, aramid or glass fibers in polymeric matrix [4]. This research focused on using Carbon Fiber Reinforced Polymer (CFRP) systems consisting of flexible sheets. The objective of this study were to investigate the effectiveness of using externally bonded CFRP strips in repair and strengthen of reinforced concrete continuous beams.
Show more

10 Read more

Shear strengthening and repair of deep beams with and without web reinforcement using near-surface mounted CFRP bars

Shear strengthening and repair of deep beams with and without web reinforcement using near-surface mounted CFRP bars

Aguilar, G., Matamoros, A.B., Parra-Montesinos, G.J., Ramírez, J.A. & Wight, J.K. (2004). Experimental Evaluation of Design Procedures for Shear Strength of Deep Reinforced Concrete Beams. ACI Structural Journal. 99(4), pp. 539-548. Ali, A., & Mezher, T. (2015). Shear Strengthening of RC without Stirrups for Deep Beams with Near Surface Mounted CFRP Rods. International Journal of

42 Read more

Strengthening of RC and FRC Beams with Precast Sifcon Laminates  An Experimental Study

Strengthening of RC and FRC Beams with Precast Sifcon Laminates An Experimental Study

Farnam et.al (2010) studied behaviour of SIFCON under triaxial compression. The stress-strain responses of HSC, HPFRC and two types of SIFCON with 0, 2, 5 and 10% volume fraction of steel fibres subjected to triaxial compression have been investigated via a comprehensive experimental program. The triaxial mechanical properties of SFRC directly depend on two significant parameters including the steel fibre volume and confining pressure. Increase of volume fraction of steel fibres and confining pressure leads to ductile behaviour in SFRC and consequently its softening behaviour changes to plastic and hardening behaviour. Increasing confining pressure and steel fibres volume increases the peak triaxial compressive strength. Also, adding steel fibres increases the Poisson's ratio for high strength concrete particularly for SIFCON with 10% volume fraction of steel fibres. Both confining pressure and fibre content have good effect on the toughness indices and they can raise the toughness of HSC up to 78 times. Shear failure occurred for HSC and HPFRC; whereas a combination of shear and crushing mode of failure was observed for SIFCON with 5% steel fibres. SIFCON with 10% of steel fibre, only crushing mode of failure was observed. SIFCONs have unique triaxial compression characteristics such as high ductility, high triaxial compressive strength and hardening behaviour. [2] Wang and Maji (1993) studied the shear properties of SIFCON by testing cored cylindrical specimens under pure torsion. Specimens of two different diameters and fibre aspect ratios were tested. Deep beams of SIFCON were tested in bending to obtain the shear resistance properties. Anisotropy in SIFCON was investigated by coring specimens from a slab of SIFCON with the fibres oriented both perpendicular and parallel to the direction of coring. The torsion of cored samples was selected as the testing technique both for the ease of obtaining specimens at a job site, and for the simplicity of analysis. This paper discusses the experimental programme and design implications when
Show more

7 Read more

EXPERIMENTAL STUDY ON SHEAR STRENGTHENING OF RC T-BEAMS WITH WEB OPENINGS USING FRP COMPOSITES

EXPERIMENTAL STUDY ON SHEAR STRENGTHENING OF RC T-BEAMS WITH WEB OPENINGS USING FRP COMPOSITES

a. MATERIAL PROPERTIES: CONCRETE Experiment is conducted with the following properties of concrete, it is specified in table no. 1, and also it is as IS: 456:2000. Another important aspect is water to cement ratio is fixed at 0.55. The mixing of water and concrete is done by using machine (concrete mixer) for better blend. The curing period of bars had been 28 days [5]. For each beam six samples of 150 x 150 x 150 mm concrete cube speciments and six samples of 150mm x 300mm cylindrical moulding structure is were made and it also kept for curing at the time of casting. Determination of compressive strength is taken on 7th and 28th days and are presented in table no. 2.
Show more

6 Read more

Shear Strengthening of RC Beams using Embedded Through Section (ETS) Technique

Shear Strengthening of RC Beams using Embedded Through Section (ETS) Technique

Mofidi et.al [2] conducted experimental tests on RC beams strengthened in shear using the embedded through section CFRP method and an average increase in shear carrying capacity of 35% was found for the ETS CFRP retrofitted specimens. CFRP rods with a plain surface were 7.83% more effective than sand coated CFRP rods. Also, Breveglieri et.al [6] after conducting a comparative study using steel and CFRP ETS bars in RC beams proved that ETS CFRP bars are more effective than ETS steel bars. Breveglieri et.al [9] also studied the influence of inclination of ETS bars, spacing of ETS bars and percentage of existing stirrups on the ETS shear strengthening efficiency. It was found that, providing 45 degrees inclination in ETS bars increases the efficiency of shear strengthening as it arrests cracks, decreasing the ETS bar spacing increases the shear strengthening effectiveness and as the percentage of already existing shear stirrups increases, the ETS shear strengthening efficiency decreases. 2. EXPERIMENTAL PROGRAMME
Show more

6 Read more

Computational study on shear strengthening of RC continuous beams using CFRP sheet

Computational study on shear strengthening of RC continuous beams using CFRP sheet

reinforced concrete continuous beams. This is includes the behavior of the beam before and after crack. Traditionally, repair of reinforced concrete is done by using steel plate as the external strengthened mechanism. However, steel plate shows weaknesses in terms of corrosion of the steel plate due to the environment. Therefore, this study tends to use CFRP as it is has better performance in terms of the reaction with the environment compared with steel plate. In this study, a computational program consisting of 5 beams will be performed subjected to experimental program with the same size and details of the beams where the experimental study was performed by other student. The CFRP composite strips were used to strengthen concrete externally at a known failure plane to resist shear stresses in shear friction. All beams were design to fails in shear with av/d 2.5. This paper describes the computational study on shear strengthening of RC continuous beams using CFRP sheet.
Show more

39 Read more

Experimental and Theoretical Investigation on Shear Strengthening of RC Precraced Continuous T-beams Using CFRP Strips

Experimental and Theoretical Investigation on Shear Strengthening of RC Precraced Continuous T-beams Using CFRP Strips

Carbon fiber reinforced polymer (CFRP) sheets are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural and shear strength. It has been widely accepted that carbon fiber reinforced polymers (CFRPs) can be used effectively to strengthen reinforced concrete (RC) members. This paper is intended to study and use externally bonded CFRP strips to repair and strengthen RC continuous T-beams, as well as investigating the influence of material (CFRP) on repair of shear defect on RC continuous T-beams. This defect will be repaired using different CFRP strips under sustained loading. Total of three RC continuous T-beams with identical sizes of 150x320x3650 mm, flange width of 400 mm and flange thickness of 120 mm were used, and the orientation involved 0/90 degree and 45/135 degree in 3 sides wrap schemes. All beams were tested under sustained loading. Tests result showed the effectiveness and shear capacity of the CFRP strengthened specimens. The shear enhancement of the CFRP strengthened beams varied between 26.57% and 38.56% over the control beam. This study confirms that the CFRP strip technique significantly enhances the shear capacity of reinforced concrete shear beams.
Show more

6 Read more

Comparative Experimental Study on Torsional Strengthening of RC Beam using CFRP and GFRP Fabric Winding

Comparative Experimental Study on Torsional Strengthening of RC Beam using CFRP and GFRP Fabric Winding

Two groups are formed which contains 15 number of beams. In first group, beams are bonded with CFRP and GFRP with second group of beam. Three beams are left as control beam. For the three beams, three strips of CFRP are bonded with epoxy resin to the beam which having size 300×300 for both sides front and back with spacing 50 mm from the end. And 100 mm spacing is provided between the strips.

7 Read more

Show all 10000 documents...