CONTACT ELEMENT ANALYSIS OF FRP REINFORCED RC BEAMS

Abstract

The use of the Fibre Reinforced Polymer (FRP) for the strengthening and rehabilitation of the reinforced concrete member is increasing in the past decades due to its anti-corrosion, high strength to weight ratio, ease transportation, high strength and high elastic modulus. Due to change in the seismic codes, the existing structure may not fulfill modern design requirements. Thus, it is required to strengthen the structures in order to gain strength and ductility as required by the seismic codes. In present study, literature review of FRP confined concrete models (design oriented and analysis oriented) and reinforced concrete (RC) beam strengthened with FRP in shear and flexure has been conferred. The mechanical and material property of the different FRP (BFRP, CFRP, GFRP) types are studied by simulating the plain concrete cylinder, prism and prism with groove to understand its compression, flexural and fracture behavior respectively using finite element (FE) tool ANSYS 14.0. 20 RC beams (2 control and 18 reinforced externally with FRP in different pattern) are model analytically for understanding its behaviour in shear and flexure with two different grades of concrete. RC portal which was design in SAP2000 for gravity load is modeled analytically in ANSYS 14.0 to predict its behaviour during lateral load. The results obtained from the finite element analysis (FEA) for plain concrete member and RC beams are compared with previous research. The axial stress-strain plot of the concrete cylinder confined with FRP obtained from FEA is compared with design oriented and analysis oriented models which corroborate with present analysis. The peak compressive strength, flexural and fracture strength of the confined concrete from present analysis compared with experimental results which shows a good correlation. The behaviour of the strengthened and conventional RC beam under two point loading is modeled using finite element analysis. The evolution of crack pattern in concrete at different load steps is studied to understand the failure mechanism of FRP strengthened reinforced concrete beam analytically. Load deflection relation, crack pattern at failure, yield and ultimate loads of FRP strengthened RC beams obtained from FEA are compared with the experimental results which shows a good iv agreement. Also, the ultimate loads from finite element analysis are calculated using design models; a good correlation was obtained with the failure loads. The load defection relationship obtained from finite element analysis of strengthened RC portal shows that the post cracking stiffness of the unreinforced portal increases with increase in number of CFRP layers. For present model, four layers of CFRP found to be sufficient to retrofit the portal to sustain during seismic events. The present analysis of reinforced concrete portal using ANSYS 14.0 software corroborated with standard research.