JACKETING Er. SHAIKH ARSHAD VJTI MTECH CM

INTRODUCTION It is a part of retrofitting i.e. repair, renovation, strengthening. Retrofitting is the modification of existing structures to make them more resistant. Jacketing is the most popularly used method for strengthening of building columns. Jacketing consists of added concrete with longitudinal and transverse reinforcement around the existing column. It improves axial and shear strength of column and major strengthening of foundation may be avoided.

NECESSITY OF JACKETING The load carried by column is increased. When there is error in design. Deterioration of column due to weathering action. Dilapidation of column. Heavy damage due to other causes like earthquake, fire etc.

ADVANTAGES OF JACKETING It increases the seismic capacity of column. Amount of work is less as foundation strengthening does not required. It increases the shear strength of column. It also increases confinement of concrete in circular columns. Steel jacketing does not increase significant weight of column and also saves construction time (curing).

TYPES OF JACKETING Reinforced concrete jacketing Steel jacketing Fiber reinforced polymer composite jacket Jacket with high tension materials like carbon fiber, glass fiber etc.

PROCEDURE OF RC JACKETING It can be employed as a repair or strengthening scheme. First prepare the surface of existing structural member. Provide shear key and reinforcement around the existing column. Bonding agent is applied over prepared surface of existing column and concrete is casted.

SHEAR KEY Drill holes of specified diameter and depth to receive shear key. Clean the drilled holes by blowing air. Inject epoxy bonding paste in drilled holes to fill it from ends to half of the holes. Insert “L” shaped shear key and allow epoxy to cure.

FUNCTIONS OF SHEAR KEY Bond properly new concrete and old concrete It holds the main reinforcement in position Treat a monolithic column Whole section is effective Resist shear failure Improve shear resistance Reduce the sliding effect between new and hollow column

REINFORCEMENT The longitudinal and transverse reinforcement as per design are fixed around the existing column. Reinforcement is properly tied with shear key using binding wire.

REINFORCEMENT JACKETING REINFORCEMENT AT KALPATRU BUYER SITE KOLSHETH ROAD THANE WEST

BONDING AGENT It is needed to properly bond new concrete with old concrete. So a bonding agent should be applied to surface of old concrete before casting of new concrete. Generally epoxy bonding paste is used as bonding agent. FUNCTIONS: I.Bond properly new concret & old concrete II.Treat a monolithic column III.Whole section is effective

ADMIXTURE A hyper plasticizer admixture is used with new concrete to increase the strength & workability. FUNCTIONS: I.It creates the concrete flowable II.Eliminates the difficulty of vibration III.Increses the strength of new concrete

CASTING OF CONCRETE Formwork is installed around the existing column and proper support is provided to withstand the newly poured concrete. Finally concrete is poured and curing is done.

STEEL JACKETING Addition of steel often applied in the form of plates and jackets. Main advantage is it does not add significant weight to structure in comparison with concrete and also it saves curing time. Disadvantage is it requires heavy equipments to handle and maintenance is more difficult.

FRP JACKETING It is a fiber reinforced polymer composite jacket used for strengthening. very effective for confinement & shear strengthening FRP composites present advantages over a traditional confinement technique. The cross section dimension of column does not increase, which permits compliance with architecture restraints. Due to light weight of FRP material, the installation procedure is faster and easier.

FRP JACKETING

REFERENCES Ravishankar.K., Krishnamoorthy.T.S, " Structural Health Monitoring, Repair and Rehabilitation of Concrete Structures", Allied Publishers, 2004 CPWD and Indian Buildings Congress, Hand book on Seismic Retrofit of Buildings, Narosa Publishers, structure-retrofit-repair-strengthening/5829/ structure-retrofit-repair-strengthening/5829/

REFERENCES rce=lnms&tbm=isch&sa=X&ved=0ahUKEwiPtuDig7vWAhVCRY8KHYpo AVYQ_AUICigB&biw=1280&bih=645#imgrc=NTZ47bWybVuUMM: rce=lnms&tbm=isch&sa=X&ved=0ahUKEwiPtuDig7vWAhVCRY8KHYpo AVYQ_AUICigB&biw=1280&bih=645#imgrc=NTZ47bWybVuUMM 1/7.% pdf

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