Effect of Glass Fibres on Flyash Based Concrete
Author(s) – Rama Mohan Rao. P,Sudarsana Rao.H, Sekar.S.Kl
Concrete is a tension-weak building material, which is often crack ridden connected to plastic and hardened states, drying shrinkage, and the like. More over, concrete suffers from low tensile strength, limited ductility and little resistance to cracking. The abundant production of fly ash from coal based thermal power plants as waste products becoming problem for their disposal and it is also hazardous to the environment. The inclusion of fly ash in glass fibre reinforced concrete reduces the environmental pollution and improves the workability and durability properties of concrete. In the present experimental investigation glass fibres in different volume fractions with 25% and 40% replacement of cement by fly ash has been used to study the effect on compressive strength, split tensile strength, flexural strength of concrete. For each mix standard sizes of cubes, cylinders and prisms as per Indian Standards were cast and tested for compressive strength , split tensile strength and flexural strength at age of 7days,28 days and 56 days as per Indian Standards.
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Finite Element Modeling on behavior of Reinforced Concrete Beam-Column Joints Retrofitted with Carbon Fiber Reinforced Polymer Sheets
Author(s) – Robert Ravi.S, Prince Arulraj.G
Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged during earthquakes and they need major repair works. Beam-column joints, being the lateral and vertical load resisting members in reinforced concrete structures are particularly vulnerable to failures during earthquakes.The existing reinforced concrete beam-column joints which are not designed as per code IS 13920:1993 must be strengthened since they do not meet the ductility requirements. The finite element method (FEM) has become a staple for predicting and simulating the physical behavior of complex engineering systems. The commercial finite element analysis (FEA) programs have gained common acceptance among engineers in industry and researchers. The details of the finite element analysis of beam-column joints retrofitted with carbon fiber reinforced polymer sheets (CFRP) carried out using the package ANSYS are presented in this paper. Three exterior reinforced concrete beam-column joint specimens were modeled using ANSYS package. The first specimen is the control specimen. This had reinforcement as per code IS 456:2000. The second specimen which is also the control specimen. This had reinforcement as per code IS 13920:1993. The third specimen had reinforcement as per code IS 456:2000 and was retrofitted with carbon fiber reinforced polymer (CFRP) sheets. During the analysis both the ends of column were hinged. Static load was applied at the free end of the cantilever beam up to a controlled load. The performance of the retrofitted beam-column joint was compared with the control specimens and the results are presented in this paper.
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Prediction of Joint Shear Strength of Concrete Beam-Column Joints Reinforced Internally with FRP Reinforcements
Author(s)– Saravanan Jagadeesan, Kumaran G
This experimental study primarily focuses on the joint shear strength of full scale size exterior concrete beam-column joint reinforced internally with Glass Fibre Reinforced Polymer (GFRP) reinforcements under monotonically increasing load on beams keeping constant load on columns. Four series of joints and totally eighteen numbers of such specimens are cast and tested for different parametric conditions like beam longitudinal reinforcement ratio, concrete strength, column reinforcement ratio, joint aspect ratio and influence of the joint stirrups at the joint. Also finite element modelling and analysis of GFRP reinforced concrete beam-column joints are performed to simulate the behaviour of the beam-column joints under various parametric conditions. Based on this study, a modified design equation is proposed for predicting the joint shear strength of the GFRP reinforced beam-column specimens based on the experimental results and the review of the prevailing design equations.
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Experimental Investigation on Behavior of Reinforced Concrete Beam Column Joints Retrofitted with GFRP–AFRP Hybrid Wrapping
Author(s)– Robert Ravi.S, Prince Arulraj.G
Upgradation to higher seismic zones of several cities and towns in the country has necessitated in evolving new retrofitting strategies. Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged during earthquakes and they need major repair works. One of the techniques of strengthening the reinforced concrete structural members is through external confinement by high strength fiber composites which can significantly enhance the strength and ductility which will result in large energy absorption capacity of structural members. Fiber materials are used to strengthen a variety of reinforced concrete elements to enhance the flexural, shear, and axial load carrying capacity of elements. Beam-column joints, being the lateral and vertical load resisting members in reinforced concrete structures are particularly vulnerable to failures during earthquakes and hence their retrofit is often the key to successful seismic retrofit strategy. The existing reinforced concrete beam-column joints which were designed as per code IS 456:2000 must be strengthened since they do not meet the requirements given in the ductility code IS 13920:1993. In this paper an attempt has been made to study the behavior of reinforced concrete beam-column joints retrofitted with glass-carbon hybrid fiber sheets. Three exterior reinforced concrete beam-column joint specimens (control) were cast and tested to failure. Two specimens had reinforcement details as per code IS 456:2000. The other specimen had reinforcement details as per code IS 13920:1993. An axial load was applied on the column. Push and pull load was applied at the free end of the cantilever beam till failure. The failed two beam-column joint specimens designed as per code IS 456:2000 were retrofitted with GFRP-AFRP/AFRP-GFRP hybrid fiber sheets wrapping to strengthen the specimens. The performance of the retrofitted beam-column joints was compared with the control beam-column joint specimens and the results are presented.
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