Performance of Reinforced Concrete Beam using CFRP, GFRP and SSWM Subjected To Torsion

Performance of Reinforced Concrete Beam using CFRP, GFRP and SSWM Subjected To Torsion

Akhil Kurian Philip

1. Tech Structural Engineering and Construction Management.

   Mangalam College of Engineering.

   Kottayam, Kerala, India.

   Dr. R Senthil Kumar

   Associate Professor, Department of Civil Engineering. Mangalam College of Engineering.

   Kottayam, Kerala, India.

   AbstractA comparative investigation of the torsional behavior of RC beams subjected to torsion with CFRP (carbon fiber reinforced polymer), GFRP (glass fiber reinforced polymer), and SSWM (stainless steel wire mesh) is presented. Ansys tool was utilized to facilitate the finite element analysis of a FRP-layered RC beam. In order to provide a plausible explanation for the efficacy of frps and sswm in terms of torsional strengthening, a series of simulations have been designed to make comparisons between different orientations. The study has analyzed the 1200mm long, 150mm wide, and 300mm deep m30 grade concrete fixed end support beam. CFRP, GFRP, and SSWM configurations are comprised of U-shaped, vertical, and diagonal strips along the full length. The torsional capacity of three sets of beams will be compared prior to and following strengthening with twists and ductility factor. On the basis of experimental studies, most suitable frps and sswm configurations are implemented into beam analysis. Results reveal that the FRP as well as SSWM layers will strengthen the structural beam.

   Keywords: CFRP, GFRP, SSWM, Torsional strenthening, Angle of twist, Finite Element Analysis, RC Beam, Ansys, Utimate torsional moment, fleural strength, shear strength;

   1. INTRODUCTION

      Using fiber reinforced polymer (FRP) composites, repair and new design procedures for reinforcing reinforced concrete (RC) structures have been developed in recent years. The FRP composite materials are gaining popularity due to their high strength-to-weight ratio, resilience to the elements and ease of application in comparison to materials such as steel. The characteristics is different that of of conventional steel reinforcement. Unlike steel, FRP materials exhibit strong tensile strength solely in the direction of the reinforcing fibers, making them anisotropic. Moreover, prior to failure, FRP composites do not display ductile behavior. The FRP composite strips are utilized to reinforce concrete externally at a predefined failure plane in order to resist shear pressures in shear friction. The FRP & SSWM composite strips are used to externally strengthen concrete at a predetermined failure plane in order to resist shear forces in shear friction. Epoxy resin or adhesive is used to adhere the FRP sheet to the tension face of the flexural member.

      The majority of research has been undertaken to examine the influence of FRP on improving flexural and shear behavior. Few studies have utilized FRP and SSWM to reinforce beams subjected to torsion. Punam Patil has studied from an experimental work based on comparison of torsional

      strengthening of rc beam using CFRP and GFRP winding. It was discovered that GFRP had a shorter fatigue life than CFRP. GFRP delivers shear strength to the beam, although not as much as CFRP. Compared to GFRP, CFRP has greater torsion strength. Depending on the slenderness ratio, CFRP failure may be caused to debonding or crushing. Failure of carbon fiber reinforced polymer can be caused by critical diagonal crack (CDC) debonding, concrete cover separation, plate end interfacial debonding, and concrete crushing. CFRP laminates or strips can be wrapped in a U-shape to increase shear strength. To enhance flexural strength, CFRP laminates can be applied to the bottom. It was determined that the degree of fiber orientation has a substantial impact on the torsional strength of RC beams.

      The numerical study employed in Ansys 19.2, finite element software is in a good agreement with the experimental results. It could predict the torsional strength using SSWM as well retrofitting effects with similar to other FRPs. The results showed that the improvement in behavior using ± 45 fiber orientation was more effective for higher values of twisting to bending moment ratios. The thickness of SSWM and FRP has significantly improved the bonding, overall strength and life span of structure. The specification of Reinforced Concrete rectangular continuous deep beam of cross section of 150 × 300 mm and 1200 mm long constructed with 500, 2 No's-12 mm and 1 No-10 mm diameter reinforcing bar at bottom and 2 No's-8mm diameter each reinforced bars at top with 6mm stirrups at spaced 100 m. The stress-strain behavior of the beam's rebars is considered to be bilinear and isotropic. The given material parameters of the geometry are listed in table.

      Fig.1.1 Reinforcement details

   2. MECHANICAL PROPERTIES

      1. Concrete

         The concrete beam is a solid element that can crack under strain and crush under compression. When the reinforcing capacity of a solid element's rebar is available, particularly for concrete material. From the perspective of nonlinear material properties, the valuable element is one that, like concrete, is capable of cracking, crushing, plastic deformation, and creep.

      2. CFRP

      Parameters	concrete
      Density(kg/m3)	2300
      Elastic modulus in x direction (GPa)	2.5e4
      Poisons ration in X-Y Plane	0.20

      Table 2.1

      D. SSWM

      SSWM is a durable strong and corrosion resistant material. It is a locally available material having different wire thicknesses and opening size. Stainless Steel refers to a series of corrosion-resistant iron (FE)-based alloys that contain at least 10.5% chromium (Cr). On the surface of the steel, chromium develops a thin coating of oxide known as the passive layer. This avoids additional surface corrosion.

      CFRP is similar to a layered base orthotropic material whose

      Parameters	CFRP
      Density(kg/m3)	1.518e-09
      Elastic modulus in x direction (GPa)	1.2334e05
      Elastic modulus in y direction (GPa)	7780
      Elastic modulus in z direction (GPa)	7780
      Shear modulus in xy direction (GPa)	5000
      Shear modulus in yz direction (GPa)	5000
      Shear modulus in zx direction (GPa)	3080
      Poisons ration in X-Y plane	0.27
      Poisons ration in Y-Z plane	0.27
      Poisons ration in Z-X plane	0.42

      strength depends on the orientation of its fibers. The CFRP consists mostly of a very thin fiber-based layered surface. Mechanical properties of Carbon fibers are as given in following Table 2.2

      Increasing the amount of chromium strengthens the passive coating, hence enhancing its resistance to corrosion. Molybdenum (MO) and nitrogen (N) are additional components that reinforce the passive film and increase its corrosion resistance. In the presence of air or water, the passive film will spontaneously reform if it is removed or damaged.

      Physical and Mechanical properties	AISI 304 SSWM
      Density Kg/m3	7850
      Wire thickness (100 mesh) mm	0.1
      Wire thickness (200 mesh) mm	0.05
      Youngs modulus GPa	200
      Yield strength MPa	280
      Ultimate tensile strength MPa	565
      Elongation %	52
      Compression strength MPa	257
      Shear modulus	77
      Poissons ratio	0.275
      Hardness, Vickers (HV)	190

      1. GFRP

         Property(Orthotropic elasticity)	Notation in ANSYS	Value	Unit
         Density		2050	Kg/m3
         Youngs Modulus X direction	E1	36.3	GPa
         Youngs Modulus Y direction	E2	10.8	GPa
         Youngs Modulus Z direction	E3	10.8	GPa
         Poissons Ratio XY	v12	0.28
         Poissons Ratio YZ	v13	0.09
         Poissons Ratio XZ	V23	0.28
         Shear Modulus XY	G12	4	GPa
         Shear Modulus XY	G13	3	GPa
         Shear Modulus XY	G23	4	GPa
         Tensile X direction	Xt	596	MPa
         Tensile Y direction	Yt	55	MPa
         Tensile Z direction	Zt	55	MPa
         Compression X direction	Xc	550	MPa
         Compression Y direction	Yc	120	MPa
         Compression Z direction	Zc	120	MPa
         Shear XY	Sxy	86	MPa
         Shear YZ	Syz	44	MPa
         Shear XZ	Sxz	86	MPa

         The externally bonded unidirectional glass fiber sheets with layers increase the beam's stability and ductility and reduce the shear failure. The glass fiber sheets are additionally wrapped externally and bonded to the RC deep beams with epoxy resin and its associated hardener. The GFRP sheets are available in a variety of sizes and thicknesses, and the effectiveness of the various sizes varies.

         Table 2.3

         Table 2.4 SSWM Physical and Mechanical properties

   3. MATERIAL MODELING AND NUMERICAL ANALYSIS

      Important for load distribution and result generation is the model's meshing. Meshing is the process of dividing a solid into small elements, which reveals the loading effects on each element's behavior. The bond between the beam and FRP and SSWM is to be considered the ideal bond. Before applying load to a beam, the beam's constraints must be specified. Beam has zero degrees of freedom UX, UY, and UZ. Moreover, for the mesh and limited condition depicted in Figure3.1. 6 geometries have been designed for the present study. Outer dimensions of all beams have been kept same. Added U wrapping of CFRP,GFRP and SSWM. CFRP of 2mm, 3mm, 4mm in vertical and angular direction (90º & 45º) is compared with ultimate torsional moment. From the literature experiment are conducted for CFRP & GFRP it shows the initial hair crack from 16.67KN & 15.74 KN started before the load failure occurs 36.82 KN & 34.85 KN . By selecting appropriate element, meshing technique and load, generating the total deformation. After cracking stage, the response is nonlinear until the maximum torque. Beyond the cracking torsional Moment 11.17 kN.m, the nonlinear behavior extends until the failure takes place. The ultimate torque and the corresponding angle of twist of control beam were found to be 24.66kN.m and 0.054 rad/m, respectively.

      1. Finite element meshing

         FEA Meshing of structural models in Ansys Mechanical is all about balancing accuracy versus computational expense. Typically, finer meshes with smaller elements produce more accurate results.

         The meshing for the analyzed deep beams is shown in Figure- 3.1.

      2. Loading and boundary conditions

         Fig3.2 Loading and boundary conditions

         Fig 3.3 GFRP U wrap 45º

         • The behavior of the beam will be evaluated with and without FRP/SSWM wrapping at the bottom.

         • In CFRP, the orientation also plays a significant role in reducing beam deflection. Therefore, analyzing the CFRP wrapping method for a structure (beam) with respect to the orientation and thickness of its CFRP layers under its loading conditions. Generally, the

           analysis orientations [45°, 90°] are taken for each single layer.

           The CFRP wrapped in a U-shape throughout its length has a higher ultimate torsional moment (UTM) of 24.66 kNm compared to its cracking torsional moment of 11.17 kNm. In cracking, the angle of twist is 0.00436 rad, while the ultimate angle of twist is 0.054 rad. The ultimate torsional moment for GFRP is 23.35kNm, whereas the cracking torsional moment (CTM) is 10.52kn. The angle of twist at fracture is 0.00326 rad, whereas the angle of twist at failure is 0.054 rad. The ultimate torsional moment for SSWM is 23.86kNm, whereas the cracking torsional moment (CTM) is 10.77kn

           Material (2mm)	Orientation 90º u-wrap (UTM)
           CFRP	24.66
           GFRP	23.35
           SSWM	23.86

           The CFRP wrapped in U-shaped 45º orientation along its length for UTM is greater than CTM, which is 10.05kNm, by 21.98kNm. The cracking and ultimate twist angles are 0.00333 rad and 0.058 rad, respectively. UTM is 20.62kNm and CTM is 8.55kNm for GFB5. The cracking and maximum angle of twist are 0.00313 rad and 0.0562 rad,. The ultimate torsional moment for SSWM is 21.07kNm, whereas the cracking torsional moment (CTM) is 8.75kn respectively.

           Table 3.1 material comparison to ultimate torsional moment Comparing the strength CFRP imparts more strength to the

           RC beam. Secondly, SSWM is found to be stronger than GFRP. Overall strength achievement can be plunged to 86%. The thickness of FRP can lessen the strain and deformation. Since the effect of CFRP is higher, based on 2mm, 3mm, 4mm the thickness variation effects is also done.

           Fig 3.4 Torsional effect on 45 u wrap CFRP

           CFRP (thickness in mm)	90ºorientation (ultimate torsion moment) kN.m	45ºorientation (ultimate torsion moment)
           2 mm	24.66	21.98
           3 mm	28.35	25.27
           4 mm	34.52	30.77

           Table 3.2 CFRP ultimate torsional moment

   4. RESULTS AND DISCUSSION

      • By assigning acceptable material parameters and an appropriate relationship between concrete and FRP, a numerical study can be utilized to anticipate the behavior of retrofitted reinforced concrete beams more precisely.

      • Most researchers examined rectangle beams for flexural and shear strengthening with different types of FRP with constant thicknesses of GFRP and which re strengthened with one, two, and three layers of FRP without curtailment. They discovered that the strength increased with the number of layers, but in a decreasing manner.

      • The flexure and shear performance of carbon-reinforced polymer is superior than the performance of glass fiber- reinforced polymer and stainless steel wire mesh.

      • The conclusion of an experimental study was that composite pattern/configuration can directly alter the behavior of load versus deflection. Both the load and deflection of the beam were changed by composite configuration. Analysis of the different configurations of FRP and SSWM under torsion Later on, the author

        can implement the optimal configuration for various support situations and loads.

      • Deflection of the retrofitted beam with CFRP is minimized by approximately 86.53 percent compared to the controlled beam, deflection of the retrofitted beam with GFRP is minimized by approximately 76.62 percent compared to the controlled beam, deflection of the retrofitted beam with SSWM is minimized by approximately 81.79 percent compared to the controlled beam, and the load carrying capacity of the retrofitted beam is greater than the controlled RC beam specimen.

   5. TORSIONAL STRENGTHENING

1. In current practise, torsional strengthening of concrete members is accomplished by one of the following techniques: 1) increasing the member cross-sectional area and adding transverse reinforcement, 2) using externally bonded steel plates and pressure grouting the gap between the plate and concrete element, or 3) applying an axial load to the member by post-tensioning. Torsion in beams is often divided into two categories: main and secondary. Primary torsion, also known as equilibrium torsion, is essentially a strength issue in which members break when torsional loads surpass the member's torsional strength. This is most prevalent in statically determined structures. In contrast, secondary torsion, which is the outcome of continuity needs in statically indeterminate structures, is the latter type, which in some cases can cause catastrophic damage if continuity requirements are disregarded. When torsion acts on an RC member, it generates two orthogonal diagonal loops, one of which is in compression and is often opposed by concrete, and the other in tension and is typically opposed by steel or other reinforcements.

2. Torsion setup

Lever arms were attached to the specimen to create a torsional moment, as seen in Figure 5.1. The specimen underwent pure torsion when the placement of a lever arm corresponded with the location of the support. The lever arm was kept beyond the two supports to apply bending and torsion simultaneously.

.

Fig 5.1 torsion test

ACKNOWLEDGMENT

I am grateful to the Almighty who is the source of knowledge and one who guides us in all aspects to bring out this paper work a successful one. I express my deep respect and profound gratitude to our college management committee for providing us an opportunity and infrastructure to undertake this paper work. I express my sincere gratitude to Prof. Dr. Vinod P

Vijayan, Principal, Mangalam College of Engineering and Prof. Dr. D. Ramesh Kumar, Head Of Civil Department for providing an opportunity to undertaken this work. I express sincere gratitude to my family and friends for encouraging in the completion of this work.

REFERENCES

[1] T.H.Patel, Dr. K.B.Parikh Strengthening of reinforced concrete beam with glass fiber reinforced polymer sheets with different configurations in shear and flexure, International journal of advance research in science & engineering, vol no. 5, Issue No. 09, September 2016.

[2] COMPARATIVE EXPERIMENTAL STUDY ON TORSIONAL STRENGTHENING OF RC BEAM USING CFRP AND GFRP

FABRIC WINDING. Punam Patil1, Vishal Yendhe2 .

[3] REVIEW ARTICLE ANALYSIS OF CONCRETE BEAM WITH

CFRP LAYERS USING ANSYS .*Udit Lahoti and Sumit Pahwa.

[4] TORSIONAL STRENGTHENING OF BEAMS USING STAINLESS ST NUMERICAL STUDY ON RETROFITTING OF BEAM COLUMN JOINT STRENGTHENED WITH CFRP

[5] N.NAVEEENA1, M.RANJITHAM2 EEL WIRE MESH (SSWM).

Paurin Shah .

[6] ANALYSIS OF CARBON-FIBER COMPOSITE STRENGTHENING TECHNIQUE FOR REINFORCED BEAM. S.D. Vanjara2 , J.M.

Dave1.

[7] ANALYSIS OF CFRP STRENGTHENED REINFORCED CONCRETE STRUCTURAL MEMBERS USING ANSYS N P S

Talauliker 1 , Purnanand Savoikar 2.