Downloaded 212 times
Uploaded byDasthagiri Kancharla
Retrofitting and rehabilitation
This document discusses rehabilitation and retrofitting of structures to improve their resistance to earthquakes. It notes that earthquakes themselves do not cause deaths but collapsed buildings do. It then discusses causes of building failures in developing countries during earthquakes. The document outlines several past damaging earthquakes and their impacts. It discusses common causes of failure of masonry and reinforced concrete buildings during earthquakes. Finally, it describes various rehabilitation and retrofitting methods that can be used to strengthen existing structures, such as adding reinforcement, jacketing, and seismic belts.
More Related Content
Similar to Retrofitting and rehabilitation
Retrofitting and rehabilitation
- 1.
- 2. EARTHQUAKES • EARTHQUAKES DONOT KILL BUT IT IS THE BUILDINGS WHICH KILL • NEARLY 5,00,000 EARTHQUAKES OCCUR EVERY YEAR • ABOUT 1,00,000 ARE FELT • Minor earthquakes occur nearly constantly around the world in places like California and Alaska in the U.S., as well as in Mexico, Guatemala, Chile, Peru, Indonesia, Iran, China, Pakistan, Portugal, Turkey, New Zealand, Greece, Italy, India and Japan, but earthquakes can occur almost anywhere. • CASUALTIES • LARGE NUMBER OF CASUALTIES OCCUR IN DEVEOPING COUNTRIES. REASONS MAY BE; – INADEQUATE DESIGN – POOR CONSTRUCTION AND MAINTENANCE – LACK OF RESOURCES – INADEQUATE KNOWLEDGE – INADEQUATE AWARENESS – INADEQUATE TRAINING – INADEQUATE SAFETY IMPLEMENTATION 2
- 3. HAITI’S E/Q, 12.1.2010;DEATHS-3,16,000; MAGNITUDE:7 3 http://haitiearthquake.web.unc.edu/
- 4. SUMATRA E/Q, 26.12.2004 DEATHS;2,27,898 MAG.9.1 4http://indonesiabackpacker.com/sumatra-earthquakes/
- 5.
- 6. NEPAL EARTHQUAKE 6 2015, Magnitude:7.9, deaths over 5000 http://www.ibtimes.co.uk/nepal-earthquake-you-cant- rule-out-more-earthquakes-come-1500883
- 7. AFGHANISTAN EARTHQUAKE 7 26th October,2015 www.slate.com/blogs/the_slatest/2015/10/26/afghanistan_and_pakistan _earthquake_is_deadly.html
- 8. 8 CAUSES OF FAILUREOF MASONRY BUILDINGS POOR QUALITY OF MORTAR IRREGULARITY IN PLANE AND VERTICAL DIRECTION NO PROVISION OF BANDS NO THOROUGH STONES HEAVY MASS CONCENTRATION AT ROOF LEVEL UNSYMMETRICAL BUILDINGS AND FULL OPENINGS UNCONFINED WALL CORNERS INADEQUATELY DESIGNED CANTILEVER ELEMENTS CAUSES OF FAILURE OF RCC BUILDINGS SOFT STOREY (ONE IN WHICH LATERAL STIFFNESS IS LESS THAN 70% OF THAT IN THE STOREY IMMEDIATELYABOVE OR LESS THAN 80% OF THE COMBINED STIFFNESS OF THREE STOREYS ABOVE) 8
- 9. • INADEQUATE FOUNDATION •POUNDING OF BUILDINGS • INADEQUATE DESIGN AND DETAILING • INADEQUATE CONNECTVITY LIKE ISOLATED STAIRCASES AND WATER TANKS NOT PROPERLY ANCHORED • POOR DETAILING OF BEAM COLUMN JUNCTIONS • PROVISION OF FLOATING COLUMNS • PLAN AND MASS IRREGULARITY • NORMALLY STRUCTURES REQUIRING REPAIR AND REHABILITATION ARE MORE SUSCEPTIBLE TO DAMAGE, HENCE REPAIR AND REHABILITATION IS VERY IMPORTANT 9
- 10. CAUSES OF DETERIORATIONOF RCC • PENETRATION OF WATER/CHEMICALS LEADING TO CARBONATION, CHLORIDE INGRESS, LEACHING, SULPHATE ATTACK, ALKALI SILICA REACTION ETC LEADING TO CORROSION IN THE REINFORCEMENT MAIN REASON OF PENETRATION OF WATER • POROSITY OF CONCRETE • PRECAUTIONS TAKEN TO PREVENT POROSITY • ADEQUATE STRENGTH OF CONCRETE • PROPER COMPACTION • WATER PROOFING ON ROOF • PLASTER ON CONCRETE • WATER PROOFING PAINTS ON EXPOSED PLASTERED SURFACE • CAUSE OF DETERIORATION OF CONCRETE 10
- 11. • AGING OFSTRUCTURE • POOR QUALITY – POOR QUALITY OF TESTING/INVESTIGATION – POOR QUALITY OF DESIGN – POOR QUALITY OF EXECUTION IN TERMS OF MATERIALS/COMPACTION/PAINTS/COVER/RCC – POOR QUALITY OF MAINTENANCE • SELECTION OF MATERIALS FOR REHABILITATION/ RETROFITTING • TECHNICAL REQUIREMENTS • COST • AVAILABILITY • EXPERT’S ADVICE • IMPORTANCE OF THE STRUCTURE • BALANCE LIFE OF THE STRUCTURE • TOXICITY OF THE MATERIAL • AESTHETIC CONSIDERATION 11
- 12. REHABILITATION METHODS • SANDBLASTING FOR REMOVAL OF CORROSION • BINDING/ADDING OF ADDITIONAL REINFORCEMENT • WELDING • ANCHORING TO THE EXISTING MEMBERS THROUGH SHEAR KEYS OR ANCHORS • SHOTCRETING • PLATE BONDING • JACKETING • FIBRE WRAPPING • UNDERPINNING PROCEDURE • REMOVAL OF LOOSE MATERIALS/RUST • PROVIDING PROTECTIVE LAYER/COATING • PROVIDING BONDING COAT BETWEEN OLD AND NEW MATERIAL/SURFACES • PROVIDING STEEL MEMBERS/WELDING/ANCHORS/ SHEAR KEYS TO ENSURE MONOLITHIC ACTION 12
- 13. RETROFITTING • PLATE BONDING •FIBRE WRAP TECHNIQUES THROUGH GLASS FIBRES/CARBON FIBRES • RCC JACKETING CAUSES OF FAILURE OF MASONRY BUILDINGS • POOR QUALITY OF MORTAR • IRREGULARITY IN PLANE AND VERTICAL DIRECTION • NO PROVISION OF BANDS • NO THOROUGH STONES • SEISMIC STRENGTHENING/ RETROFITTING • SEISMIC STRENGTHENING • MAIN PURPOSE OF SEISMIC STRENGTHEING IS TO UPGRADE/PROVIDE THE SEISMIC RESISTANCE ON A BUILDING SO THAT IT BECOMES SAFER UNDER EARTHQUAKE OCCURANCES 13
- 14. SELECTION OF MATERIALSAND TECHNIQUES FOR RETROFITTING CEMENT STEEL ◦ BOLTS, RODS, ANGLES, BEAMS, CHANNELS, EXPANDED METAL, WELDED WIRE FABRIC ADMIXTURES TO IMPROVE NON-SHRINKAGE (GROUTS CONSISING POLYMER, NON-SHRINK CEMENT AND SPECIAL SANDS), BOND (EPOXY RESINS) ETC. SEQUENCE OF RETROFITTING REPAIR/REHABILITATION ALL CRACKS SHOULD BE FULLY REPAIRED ◦ PRESSURE INJECTION OF NON-SHRINK CEMENT POLYMER GROUT FOR 0.5 TO 5 MM CRACKS ◦ REPAIR BY EXPANSIVE CEMENT MORTAR, QUICK SETTING CEMENT, ADDL. SHEAR OR FLEXURAL REINFORCEMENT, STEEL MESH, STEEL RODS 14
- 15. REPAIR/STRENGTHENING OF WALLS BY GROUTING (CEMENT WATER MIXTURE OR POLYMERIC MORTAR) BY ADDITION OF VERTICAL REINFORCEMENT CONCRETE COVERINGS ON THE TWO SIDES OF THE WALL BY PRESTRESSING WALL HORIZONTAL SEISMIC BELTS ◦ IN CASE OF RCC SLAB ROOF BELT NOT REQUIRED ◦ NOT REQUIRED AT PLINTH LEVEL UNLESS PLINTH HEIGHT IS MORE THAN 900 MM ◦ ON ALL WALLS ◦ ON BOTH THE FACES 15
- 16. ON ALL WALLS ONBOTH THE FACES ABOVELINTEL 16
- 17.
- 18.
- 19. VERTICAL SEISMIC BELTSAT CORNERS AT THE CORNERS OF ROOMS JUNCTIONS OF THE WALLS WIDTH ON EACH SIDE OF THE CORNER TO BE KEPT 25 MM EXTRA TO THE WIDTH OF THE MESH REIFORCEMENT TO BE STARTED BELOW 300 MM BELOW PLINTH LEVEL 19
- 20.
- 21. VERTICAL REINFORCEMENT AT INSIDECORNER 21
- 22. ROOFS CONSISTING OFSTEEL JOISTS FLAT OR SEGMENTAL ARCHES MUST HAVE HORIZONTAL TIES HOLDING THE JOISTS HORIZONTALLY IN EACH ARCH SPAN SO AS TO PREVENT SPREADING OF JOISTS 22