68th SOEAA, Florianapolis, Brazil 68th SOEAA, Florianapolis, Brazil SEISMIC REHABILITATION SEISMIC REHABILITATION OF RC STRUCTURES- OF RC STRUCTURES- AN OVERVIEW AN OVERVIEW A. T. Tankut A. T. Tankut Middle East Technical University, Middle East Technical University, Turkey Turkey
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68th SOEAA, Florianapolis, Brazil SEISMIC REHABILITATION OF RC STRUCTURES- AN OVERVIEW A. T. Tankut Middle East Technical University, Turkey.
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68th SOEAA, Florianapolis, Brazil68th SOEAA, Florianapolis, Brazil
SEISMIC REHABILITATION SEISMIC REHABILITATION OF RC STRUCTURES-OF RC STRUCTURES-
AN OVERVIEWAN OVERVIEW
A. T. TankutA. T. TankutMiddle East Technical University, TurkeyMiddle East Technical University, Turkey
A NOTE ON THE CONTENTSA NOTE ON THE CONTENTS
* Initial intention was to discussInitial intention was to discuss the the philosophy behind seismic philosophy behind seismic strengtheningstrengthening under the title under the title “Seismic Rehab Strategy”“Seismic Rehab Strategy”
* Considering the audience consisting of Considering the audience consisting of various disciplines, various disciplines, policypolicy was changed. was changed.
* Basic concepts and methods that may Basic concepts and methods that may interest the audience will be reviewed.interest the audience will be reviewed.
OUTLINEOUTLINE
* Introduction and Basic ConceptsIntroduction and Basic Concepts
* Common Structural SystemsCommon Structural Systems
* Rehabilitation Techniques AvailableRehabilitation Techniques Available
* An Innovative Rehabilitation An Innovative Rehabilitation TechniqueTechnique
““Earthquake”Earthquake” is a natural is a natural phenomenonphenomenon
* It is It is tolerabletolerable in countries where in countries where the people and the built the people and the built environment are prepared for it;environment are prepared for it;
* It leads to a It leads to a disasterdisaster in countries in countries wherewhere the built environment the built environment and and the peoplethe people are are not prepared for it. not prepared for it.
INTRODUCTIONINTRODUCTION
““Earthquake Preparedness”Earthquake Preparedness” consists of consists of
* Disaster ManagementDisaster Management (post-quake) – (post-quake) – Search & rescue, sheltering, food, Search & rescue, sheltering, food, medical care etc.medical care etc. ((EasyEasy but but not not effective)effective)
* Risk ManagementRisk Management (pre-quake) – Safe (pre-quake) – Safe towns, safe structures, well educated towns, safe structures, well educated public, well trained engineers, effective public, well trained engineers, effective financing etc. financing etc. ((HardHard but but very very effective)effective)
INTRODUCTIONINTRODUCTION
* Seismic rehab of the existing bldg Seismic rehab of the existing bldg stock is the most critical item in risk stock is the most critical item in risk mitigation.mitigation.
* A huge unsafe building stockA huge unsafe building stock exists. exists.
* A systematic assessment reveals thatA systematic assessment reveals that
-- A small number is seismically safe,A small number is seismically safe,
- A certain portion is to be demolished,- A certain portion is to be demolished,
- - The majority is to be The majority is to be strengthenedstrengthened..
COMMON COMMON STRUCTURAL STRUCTURAL
SYSTEMSYSTEM
COMMON TYPE OF STRCOMMON TYPE OF STR
* Reinforced concrete Reinforced concrete framed framed building structuresbuilding structures are common in are common in southeast Europe including southeast Europe including Turkey.Turkey.
* Partitioning walls ofPartitioning walls of hollow brick hollow brick masonrymasonry make the structure make the structure infilled frame and changes its infilled frame and changes its behaviour.behaviour.
COMMON DEFICIENCIESCOMMON DEFICIENCIES
Of these RC framed building structures Of these RC framed building structures with hollow brick masonry infill,with hollow brick masonry infill,
* * Low-rise (1Low-rise (12 floor)2 floor) are not vulnerable; are not vulnerable;
* * High-rise (> 10High-rise (> 1012 floor)12 floor) buildings are buildings are .. carefully designed and constructed; carefully designed and constructed;
* * Mid-rise (3Mid-rise (38floor)8floor) bldgs of inferior bldgs of inferior .. material, poor design and construction material, poor design and construction .. quality present the major problem. quality present the major problem.
COMMON DEFICIENCIESCOMMON DEFICIENCIES
Mid-rise buildings of inferior qualityMid-rise buildings of inferior quality
* Constitute the Constitute the majoritymajority in small in small towns;towns;
* Collapse in the Collapse in the pancake modepancake mode; thus; thus
* Are responsible from the high number Are responsible from the high number of of human losses and severe damagehuman losses and severe damage,,
* Are generally too good for demolition;Are generally too good for demolition;
* Are greatly in Are greatly in need of rehabilitationneed of rehabilitation..
COMMON DEFICIENCIESCOMMON DEFICIENCIES
Common deficiencies of such Common deficiencies of such buildings:buildings:
Methods for beam strengtheningMethods for beam strengthening
* For bendingFor bending - - Additional layer with new steelAdditional layer with new steel- CFRP applications to the same - CFRP applications to the same effecteffect
* For shearFor shear- - External clampsExternal clamps- CFRP applications to the same - CFRP applications to the same effecteffect
JOINT STRENGTHENINGJOINT STRENGTHENING
Methods for joint Methods for joint strengtheningstrengthening
* Masonry infillsMasonry infills,, reinforced with reinforced with highhigh strength precast concrete panelsstrength precast concrete panels
* Steel cross bracingSteel cross bracing
* Post tensioningPost tensioning
* External rigid frame to support the strExternal rigid frame to support the str
AN INNOVATIVE AN INNOVATIVE REHABILITATION REHABILITATION
TECHNIQUETECHNIQUE
INTRODUCTIONINTRODUCTION
The basic question:The basic question:
* Cast-in-place reif conc infilled frame Cast-in-place reif conc infilled frame technique is technique is suitable for post-quake suitable for post-quake repairrepair of the evacuated buildings; but of the evacuated buildings; but not for pre-quake rehabilitationnot for pre-quake rehabilitation of the of the buildings still in use.buildings still in use.
* Suitable techniques should be Suitable techniques should be developed.developed.
THE CHALLENGETHE CHALLENGE
To develop a rehabilitation method,To develop a rehabilitation method,
* Suitable for the common building Suitable for the common building type (Hollow brick infilled RC frame)type (Hollow brick infilled RC frame)
* Practical & economical, and above allPractical & economical, and above all
* Occupant friendly Occupant friendly ((no more disturbance no more disturbance than an ordinary painting job)than an ordinary painting job)
THE ANSWERTHE ANSWER
The answer is The answer is OFROFR (occupant friendly rehab)(occupant friendly rehab)
* To reinforce existing masonry infill wall To reinforce existing masonry infill wall with epoxy bonded PC panels, which with epoxy bonded PC panels, which are,are,
- Light enough to be handled by two- Light enough to be handled by two
- Small enough to go through doors- Small enough to go through doors
- Relatively thin, 40~50 mm (high str)- Relatively thin, 40~50 mm (high str)
- Connected to infill wall by epoxy, and - Connected to infill wall by epoxy, and to frame by epoxy bonded dowelsto frame by epoxy bonded dowels