SEISMIC RETROFITTING OF CONCRETE BUILDINGS GUIDED BY AMBILI RAVI, LECTURER, DEPT. OF CIVIL ENGG, SNGCE. PRESENTED BY ANU THAMPY, SEM -7, ROLL NO-9, SNGCE.

INTRODUCTION

EARTHQUAKE GENERATION EARTHQUAKES EARTHQUAKE GENERATION

SEISMIC RETROFITTING NEED FOR RETROFITTING BUILDING DEFICIENCIES STEPS TAKEN PRIOR TO RETROFITTING

NEED FOR RETROFITTING \ MAKES BUILDING SAFER AND LESS PRONE TO DAMAGE CONSTUCTION TECHNIQUES ARE IMPROVED DURABILITY AND AESTHETIC APPEARANCE ARE REDUCED AFTER DAMAGE DEMANDS ON EXISTING STRUCTURES ARE INCREASING UNEXPECTED EXTRA LOADS ARE TO BE CARRIED MAKES IMPROVEMENTS TO AN EXISTING BUILDING

BUILDING DEFICIENCIES PLAN IRREGULARITIES. VERTICAL IRREGULARITIES

PLAN IRREGULARITY Torsional irregularity due to plan asymmetry and eccentric mass from water tank. Re-entrant corners in U-,L- and T-shaped building. Diaphragm discontinuity due to openings or staggered floors along with absence of collector elements. Out-of-plane offset for floating columns along perimeter. Nonparallel lateral load resisting systems.

VERTICAL IRREGULARITIES Stiffness irregularity , extreme soft storey due to open ground storey. Mass irregularity. Vertical geometric irregularity from set-back towers. In-plane discontinuity for floating columns along perimeter. Weak storey for open ground storey.

VARIOUS STEPS TAKEN PRIOR TO RETROFITTING SCREENING EVALUVATION RETROFIT

TRADITIONAL APPROACHES TO SEISMIC RETROFITTING

INNOVATIVE APPROACHES TO SEISMIC RETROFITTING STIFFNESS REDUCTION. DUCTILITY INCREASE. DAMAGE CONTROL STRUCTURES. ACTIVE CONTROL.

STIFFNESS REDUCTION BY THE PRINCIPLE OF SPRINGS IN SERIES

Seismic Isolator Placement Alternates

LEAD RUBBER BEARING (Top Mounting Plate Not Shown) Energy Dissipation Core Cover Rubber Internal Rubber Layers Steel Reinforcing Plate Bottom Mounting Plate It is made from layers of rubber sandwiched together with layers of steel. The bearing is very stiff and strong in the vertical direction but flexible in the horizontal direction.

WORKING OF BASE ISOLATION SYSTEMS (BUILDING WITH BASE ISOLATION) BUILDING WITHOUT BASE ISOLATION WORKING OF BASE ISOLATION SYSTEMS (BUILDING WITH BASE ISOLATION)

DAMAGE CONTROLLED STRUCTURE

X-BRACED FRICTION DAMPER

CFRP APPLICATION ON A COLUMN

CONCLUSION Makes buildings more resistant to earthquakes. Retrofit techniques are applicable for other natural hazards. Give safety to the occupants. Cost effective. Still, no such a technique is completely earthquake proof. Challenging to select a technique.

REFERENCE Giuseppe Oliveto, Massime Marletta,(2005), Seismic Retrofitting of Reinforced Concrete Buildings using Traditional and Innovative Techniques, ISET Journal of Earthquake Technology, 454, pp 21-46. Steven.L.Kramer,(2000), Geotechnical Earthquake Engineering, En., Academic Press, New York, 1988. www.wikipedia.org www.seismicsafety.com www.cal-quake.com

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