COMPARATIVE STUDY OF BEAMS BY USING DIFFERENT TYPES OF RETROFITING TECHNIQUES

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 10, Issue 04, April 2019, pp , Article ID: IJCIET_10_04_091 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed COMPARATIVE STUDY OF BEAMS BY USING DIFFERENT TYPES OF RETROFITING TECHNIQUES Mansi Saini Scholar, Department of Civil Engineering, Chandigarh University, Mohali, India Aditya Tiwary Assistant Professor, Department of Civil Engineering, Chandigarh University, Mohali, India ABSTRACT The main aim of this study was to increase the strength of beams by using different types of jacketing techniques and checks the most cost-efficient methods. In this paper, the reinforced concrete (RC) jacketing and carbon fiber reinforced polymer jacketing was used for retrofitting the beams. In this research study, 100 mm thickness of RC jacketing is used in all four sides of beam and carbon fiber reinforced polymer (CFRP) of different thickness of sheet are used. The point load test is done on loading frame machine and check the crack, ultimate strength and comparing the results and cost of all different types of retrofit techniques for reinforced concrete. Analyses was also performed on ABAQUS software and then validation is done by comparing the deformation and stress behavior in ABAQUS and experimentally. It was observed that the RC jacketing strength increased 63% and 48.5% strength increase in CFRP. The test results show that the RC jacketing gain more strength then other jacketing methods and increase the flexural strength. Key words: Beam, RC jacketing, CFRP jacketing. Cite this Article: Mansi Saini and Aditya Tiwary, Comparative Study of Beams by Using Different Types of Retrofiting Techniques, International Journal of Civil Engineering and Technology 10(4), 2019, pp INTRODUCTION Although reinforced concrete structures have high strength but due to earthquake and other effects like wind load, seismic load and creep, the structure get fails, deteriorates, losses its strength over time [1]. As the structure reaches its service life the load carrying capacity of structure also decreases. So, the structure gets retrofitted by using different methods of jacketing. It may necessary to combine both local and global retrofit strategies under feasible & economical retrofit scheme

2 Comparative Study of Beams by Using Different Types of Retrofiting Techniques 1.1. Global Strategies When a building facieses several deficient and damage due to earthquake, wind & lateral load effect it is necessary to provide strength & lateral load resisting element so addition of infill walls, shear walls, bracing increases the strength. Local Strategies Local strategies are done in beam, column, beam column joints in local strategies retrofit are done by jacketing that is steel, concrete or FRP and then comparisons are done to check which are more suitable for multi-story building. 2. MATERIALS AND METHODS Cement An ordinary Portland cement (OPC) of grade 43 was used for the construction work with specific gravity The bulk density of cement is kg/m 3. Sand Crushed sand was used with specific gravity 2.64, here crushed sand used for the good bonding strength. The bulk density is kg/m 3 and the water absorption is 1%. Coarse aggregate The maximum size of aggregate of 10 mm having specific gravity 2.62 was used and grading of aggregate was zone II. The bulk density is 1476 kg/m 3 and the water absorption is 6%. Carbon fibre CFRP is having high strength, durability. It is used for high strength and rigidity of different thickness and numbers of layers used for retrofitting of beam. Epoxy resin Epoxy resin was used for good bonding between concrete surface and carbon fibre sheet Experimental Programme RC beam have been casted and tested under different loading condition. Four beams were casted of size mm 3, the span length of beam is 1500 mm and width are 230 mm. In this the beam are design by using limit state method and the concrete grade of M40. The quantity of materials is calculated by using the code that is mix design specification BIS 10262:2009. The size of reinforcement is 4 no s 12 mm diameter bar used in both compression and tension member and grade was Fe 415. The stirrups size is 6 No s with 8 mm diameter of 250 mm centre to centre spacing [2]. The load applied at centre as shown in Figure 1. Before beam, two cubes were casted and tested for check the compressive and tensile strength that is 39.5 N/mm 2, 5 N/mm 2. Figure 1 Point load on beam editor@iaeme.com

3 Mansi Saini and Aditya Tiwary 2.2. Casting of RC beams The beams were cast. The size of all specimens was identical and shape was square having dimensions mm 3. The rectangular wooden mould was prepared as shown in Figure 2 and rectangular reinforcement cage also performed as shown in Figure 2. The mixing of concrete was done by using mix design specification BIS 10262:2009, after mixing beams were casted by proper alignment of reinforcement of size main bar was used 12 mm and shear reinforcement was 8 mm with 250 mm centre to centre spacing. The casted of beams were shown in Figure 3. After casting of beams, the first point load was applied on beam to check the crack load and ultimate load of all control beams. After testing, the all control beams were retrofitted by using RC jacketing, CFRP jacketing. CFRP used to increase the strength and its also helps to protect the beam from corrosion [3,4] Figure 2 Plywood moulds with Reinforcement cage Figure 3 casting of beams 2.3. Retrofitting of beams RC jacketing s. All four sides of beam were retrofit by using RC jacketing. The 100 mm jacketing used in all four sides of beams with reinforcement size 4 No s of 16 mm diameter bars and shear reinforcement size 6 no s 8 mm diameter bar 280 mm center to center spacing. The size of beam become mm 3, the span length became 1700 mm and cross section area became mm 2 and concrete grade M45 and steel grade 415 was used. Retrofitting of beam shown in Figure 4. Figure 4 Retrofitting of beam Figure 5 Recasting of beam Carbon Fiber reinforced polymer The beam was wrapped with all four sides by CFRP sheets of different thickness that is 0.3 mm [5]. Before providing the CFRP sheet on all sides of beam first made the surface rough and clean by using wire brush and then mixing the epoxy resin properly in any container. After mixing, apply the epoxy primer on beam by using brush for a good bond between the concrete surface and CFRP sheet and the wrap the beam by using CFRP sheet of thickness editor@iaeme.com

4 Comparative Study of Beams by Using Different Types of Retrofiting Techniques mm with single layer or also unidirectional [6,7] and then check it for strength. The retrofitting of beam was kept under room temperature and work also done on room temperature for protecting the moisture. The retrofitted beam cured for 3 days under room temperature. 3. TEST AND RESULTS 3.1. Testing of beams All beams were tested under loading frame machine for the flexural strength. four beams were casted, all beams tested under point load by using loading machine. After testing the crack pattern and crack load were checked and also checked the ultimate load. Figure 6 Experiment test set up and point loading arrangment Figure 7 Control beam with crack and failure pattern Table 1 Deflection of control beams at crack load and ultimate load Sr. No. Crack point Ultimate point Crack load (kn) Deflection (mm) Ultimate load (kn) Deflection (mm) B B B B Table 2 Deflection of retrofitted beams at crack load and ultimate load Sr. No. Crack load (kn) Deflection (mm) Ultimate load (kn) Deflection (mm) B1 (RC jacketing) B2, B3 (CFRP-0.3MM) B4 (CFRP-0.4MM) editor@iaeme.com

5 Mansi Saini and Aditya Tiwary Then beam was retrofitted and tested again. The specimen B1 retrofitted by using RC jacketing and then strength was checked by applying point load on particular surface also check the stress and displacement of all beam that is control beam and all retrofitted beams. When load was applied first crack load was checked and deflection of beam and then checked the ultimate load. The specimen B3 and B4 retrofitted by CFRP sheets of thickness 0.3 mm and 0.4 mm with single layer and then load was applied and check the strength. After applying the jacketing on all beams, comparing the results with control beam and retrofitted beams which was retrofit by different techniques and then check which was most suitable and cost effected methods and also check the strength also the behavior of load deflection of all beams was compared. The deflection graph was plotted. The RC jacketed beam has more strength as compared to control and other retrofitted beams and less in cost also. It has been found that the crack load of beams without retrofit is between 60 kn to 62 kn and ultimate load between 120 kn. The control beam has maximum deflection and less ultimate load carrying capacity and shear capacity. The crack load of RC jacketed is beam 120 kn to 140 kn and ultimate load between 180 kn to 200 kn. In CFRP jacketing with single layer of sheet the first crack load appeared at 110 kn Software analysis The RC beam design in software ABAQUS with dimension mm 3. First the different -2 part were prepared and then assign the properties of concrete and steel and then assemble the all parts to make it RCC beam as shown in fig. The interaction part is done to make the structure interact with each other so it shows deformation properly and define the penalty friction coefficient 0.8 in tangential behavior. The simply supported support was assign by using boundary condition and applied load crack and ultimate load to check deflection and then compare the result with experimental work. The important part was meshing which means that it checks every part of nodes. Field output and history output are done in job analysis part and the step increment is the most important which is decided by the load. Then creating a job for analysis, the result. Table 3 Deflection of control beams at crack load and ultimate load in software Sr. No. Crack point Ultimate point Crack load (kn) Deflection (mm) Ultimate load (kn) Deflection (mm) B B B B Table 4 Deflection of retrofitted beams at crack load and ultimate load Sr. No. Crack load (kn) Deflection (mm) Ultimate load (kn) Deflection (mm) B1(RC jacketing) B2, B3(CFRP-0.3MM) B4(0.4mm) editor@iaeme.com

6 Comparative Study of Beams by Using Different Types of Retrofiting Techniques Figure 8 Deformation and stress in control beam 3.3. Validation In this it shows that during the experimental work the maximum deflection and bending occur at center of beam and also in analytical work. Figure 9 Deformation in control beam Figure 10 deflection of control beams (Series 1 software results and series 2 experimental editor@iaeme.com

7 Mansi Saini and Aditya Tiwary 4. CONCLUSIONS The flexural behavior of reinforced concrete beams strengthens by RC, Steel, CFRP sheets having different thickness are studied and investigated and following conclusion were made: 1. Due to strengthen by RC, CFRP, ultimate strength and bearing capacity of beams increased. 2.The average crack load of control beam and retrofitted by RC was found 60 kn to 61 kn and 140 kn ultimate load of control beam but the crack load of retrofitting beams found between 120 kn and ultimate load 200 kn 3. The ultimate strength of RC jacketing increase 63% more than the control beam and other jacket beam. 4. The ultimate strength of CFRP jacketing increase 48.5%more than the control beam. It was found that CFRP is also good for corrosion resistance. 5. All four sides jacketing of beams has more strength and bearing capacity. It increases the capacity of resistance as the demand of load increase. 6. These all methods help for future to retrofitting the structure either beam, column or also define the crack pattern, depth and failure load. 7. The cost of RC jacketing is less than steel and CFRP, the CFRP has large cost as compared to steel and RC. So, RC jacketing is good in both strength and cost. REFERENCES [1] Bhavar Dadasahebet. al. studied the structural behavior of RCC building IRJET journal (2013). [2] S.P. Tastani, establishes the confinement model. Construction and building material (2013). [3] AhmedKhalifa et.al Improve shear capacity of existing RC beams using CFRP composites. Cement and concrete Elsevier science (2000) [4] Tastani et al (2006), recovery of seismic resistance in corrosion-damaged reinforced concrete through FRP jacketing Canadian journal of civil engineering. [5] Nalivenkatakrishna et.al study the behavior of reinforced concrete beams using externally bonded CFRP. Journal of emerging technologies and innovative. [6] Dr P. Sivakumar investigate the behavior of concrete beams by using CFRP unidirectional laminates under loading international conference on emerging technology trends [7] Michale et al the behavior of concrete confined with reinforced polymers (FRPs) journal of composites for construction (2005). [8] Abhishekjodwat Improving shear capacity of existing RC beams using external bonding of steel plates", Engineering Structures, (2016), 27,