Repair, rehabilitation and retrofitting of structures - RRS

Strengthening of Structural elements, Repair of structures distressed due to corrosion, fire, Leakage, earthquake – DEMOLITION TECHNIQUES - Engineered demolition methods - Case studies.

1. DEPARTMENT OF CIVIL ENGINEERING CE6021-REPAIR AND REHABILITATION OF STRUCTURE UNIT V – REPAIR, REHABILITATION AND RETROFITTING OF STRUCTURES PRESENTATION BY SHANMUGASUNDARAM N ASSISTANT PROFESSOR 3/5/2019 CE6021-RRS/unit 5 by,Shanmugasundaram.N 1 /35 SNS COLLEGE OF ENGINEERING

2. UNIT V REPAIR, REHABILITATION AND RETROFITTING OF STRUCTURES Strengthening of Structural elements, Repair of structures distressed due to corrosion, fire , Leakage, earthquake – DEMOLITION TECHNIQUES - Engineered demolition methods - Case studies. CE6021-RRS/unit 5 by,Shanmugasundaram.N 2 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

3. CE6021-RRS/unit 5 by,Shanmugasundaram.N 3 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

4. DEMOLITION TECHNIQUES CE6021-RRS/unit 5 by,Shanmugasundaram.N 4 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

5. WHAT IS DEMOLITION???? ? Demolition means dismantling, razing, destroying or wrecking any building or structure or any part by pre-planned and controlled methods. Demolition is the tearing-down of buildings and other structures CE6021-RRS/unit 5 by,Shanmugasundaram.N 5 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

6. WHY DEMOLITION???? The structures which have already passed their design life need to be reconstructed, for safety and operational requirements. The old structures need to be demolished for replacement by new structures . Small structures can be dem o lished by manual methods but machinery and a dvanced techniques are required for demolition of bigger structures. Advanced techniques are also required for faster demolition and demolition in confined areas. CE6021-RRS/unit 5 by,Shanmugasundaram.N 6 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

7. SEQUENCE CE6021-RRS/unit 5 by,Shanmugasundaram.N 7 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

8. CE6021-RRS/unit 5 by,Shanmugasundaram.N 8 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 SEQUENCE

9. CE6021-RRS/unit 5 by,Shanmugasundaram.N 9 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 SEQUENCE

10. DEMOLITION SEQUENCE Demolition sequence shall be determined based on Actual site conditions, Restraints, The building layout, The Structural layout and its construction.In general, the following sequence shall apply: UTILITIES disconnection. Electricity,plumbing , waterlines,drainage conections etc.. All cantilevered structures , canopies, verandas and features attached to the external walls shall first be demolished prior to demolition of main building and its internal structures on each floor When demolishing the roof structure, all lift machine rooms and water tanks at high level shall be demolished in “ top down ” sequence to the main roof level CE6021-RRS/unit 5 by,Shanmugasundaram.N 10 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

11. DEMOLITION SEQUENCE CE6021-RRS/unit 5 by,Shanmugasundaram.N 11 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

12. DEMOLITION SEQUENCE CE6021-RRS/unit 5 by,Shanmugasundaram.N 12 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

13. DEMOLITION SEQUENCE 3)Demolition of the floor slabs shall begin at mid span and work towards the supporting beams. CE6021-RRS/unit 5 by,Shanmugasundaram.N 13 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

14. DEMOLITION SEQUENCE Floor beams shall be demolished in the order of cantilevered beams, secondary beams and then main beams. Non-load bearing walls shall be removed prior to demolition of load bearing walls. CE6021-RRS/unit 5 by,Shanmugasundaram.N 14 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

15. DEMOLITION SEQUENCE CE6021-RRS/unit 5 by,Shanmugasundaram.N 15 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

16. DEMOLITION SEQUENCE I f site con d it i o n s p e r m i t, t h e first f l o o r sl a b directly above the ground floor may be demolished by machine standing on ground. CE6021-RRS/unit 5 by,Shanmugasundaram.N 16 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

17. DEMOLITION METHODS Demolition methods can vary depending on the following The area where it will be held on Time available The building material The purpose of the demolition and The way that debris is going to be disposed. Time saving methods are more expensive than the slower ones. If noise, dust, and vibrations are to be restricted, it will add to the cost of demolition CE6021-RRS/unit 5 by,Shanmugasundaram.N 17 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

18. MANUAL METHOD Manual methods are carried out top down, proceeding, in general, from the roof to ground. The sequence of demolition may vary, depending on Site conditions and Structural elements to be demolished CE6021-RRS/unit 5 by,Shanmugasundaram.N 18 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

19. MANUAL METHOD For reinforced concrete buildings, jack hammers are commonly used to break down the concrete. Oxy-acetylene torch could be used to cut the reinforcements. The reinforcements shall remain until all the concrete connecting to or supported by the reinforcement is broken away or when its support is no longer required. In congested areas , these features could have critical impact on the safety of the public . CE6021-RRS/unit 5 by,Shanmugasundaram.N 19 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

20. MANUAL METHOD Demolition of these features shall be performed with extreme caution. If rope or tie wires are used to pull down the structural elements, the pulling wire must be at least 4 times stronger than the anticipated pulling force. In addition, workers shall be shielded from the rope or tie wires. CE6021-RRS/unit 5 by,Shanmugasundaram.N 20 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

21. DEMOLITION BY MACHINES CATERPILLAR 385C HIGH REACH DEMOLITION EXCAVATOR RIPPING DOWN BUILDING.mp4 CE6021-RRS/unit 5 by,Shanmugasundaram.N 21 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

22. DEMOLITION BY MACHINES The sequence of demolition by machine i s typ i cal l y the same as the t o p do w n manual method, except that most of the demolition is done by mechanical plant. The demolition begins with the lifting of the mechanical plant on to the building top floor. When rope or tie wire is used for pulling, the workers shall be protected or stay away from the area within reach . CE6021-RRS/unit 5 by,Shanmugasundaram.N 22 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

23. DEMOLITION BY MACHINES Adequate propping shall be installed at floor levels below the working floor to safely support the operation of the mechanical plant. The movement of the mechanical plant shall only be within the propped area . The propped areas shall be suitably marked. The movement of the mechanical plant shall be prohibited within 2 m of the building edge, within 1 m of any floor openings or any cantilevered structures. CE6021-RRS/unit 5 by,Shanmugasundaram.N 23 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

24. DEMOLITION BY MACHINES The mechanical plant shall be lifted onto the roof of the building by the use of mobile crane or other appropriate means as approved. The machine shall descend down to the next floor by means of a ramp . The ramp may be a temporary structure or other appropriate design. The slope of the ramp shall be no steeper that 1.75 to 1 or as recommended by the machine manufacturer. As an alternative, the machine may also be lowered to the next floor. CE6021-RRS/unit 5 by,Shanmugasundaram.N 24 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

25. DEMOLITION BY MACHINES CE6021-RRS/unit 5 by,Shanmugasundaram.N 25 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

26. DEMOLITION BY MACHINES CE6021-RRS/unit 5 by,Shanmugasundaram.N 26 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

27. CRUS H ERS The crusher attachment b r eaks the concrete an d the r e inforcem ent by the hydraulic thrust through the long boom arm system. The hydraulic crusher can be operated from the ground outside the building . This method is also suitable for dangerous buildings, silos and other industrial facilities. The operation shall have a minimum clear space of ½ the building height as a safety zone for the falling debris. The excavator shall operate on firm ground that can support the machine during the crusher operation. Each section of the structure shall be demolished in a top down sequence . CE6021-RRS/unit 5 by,Shanmugasundaram.N 27 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

28. DEMOLITION BY MACHINES CE6021-RRS/unit 5 by,Shanmugasundaram.N 28 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

29. DEMOLITION BY MACHINES Hy d raul i c shears Pulverizers Grapple CE6021-RRS/unit 5 by,Shanmugasundaram.N 29 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

30. DEMOLITION BY WRECKING BALL Wrecking ball in action demolishing a concrete building.mp4 CE6021-RRS/unit 5 by,Shanmugasundaram.N 30 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

31. DEMOLITION BY WRECKING BALL The wrecking ball application consists of a crane equipped with a steel ball. The destruction of the building is by the impact energy of the steel ball suspended from the crawler crane. The wrecking ball operates outside the building. This method is suitable for dilapidated buildings, silos and other industrial facilities. However, the operation requires substantial clear space. The application also demands high level skill operators and well. CE6021-RRS/unit 5 by,Shanmugasundaram.N 31 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

32. DEMOLITION BY WRECKING BALL The balling of each section of the structure shall proceed from top to bottom. Recommended techniques for the wrecking ball operations include (1) Vertical Drop -free falling of the wrecking ball onto the structure and (2) Swing in line - swinging of the ball in-line with the jib. A second dragline will normally connect to the ball horizontally to control the ball motion. The ball shall be swung into the building CE6021-RRS/unit 5 by,Shanmugasundaram.N 32 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

33. DEMOLITION BY WRECKING BALL The jib or boom shall be operated with no less than 3m above the portion of the structure being demolished. Clear space for operation between the crane and the structure being demolished shall be ½ of the height of structure , with additional distance between crane and boundary wall for maneuverability . High strength wire shall be used to allow pullout of the wrecking ball from potential traps. To minimize the dust impact on the surrounding area, the structure to be demolished shall be pre- soaked with water before demolition. Water spraying shall continue on the structure during demolition. The o pe r a ti o n shall not b e p e rf o rm e d a dj a c e n t to overhead power lines . The site shall be entirely fenced off to forbid public access CE6021-RRS/unit 5 by,Shanmugasundaram.N 33 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

34. DEMOLITION BY EXPLOSIVES TOP 20 EPIC DEMOLITION OF BUILDINGS.mp4 CE6021-RRS/unit 5 by,Shanmugasundaram.N 34 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

35. DEMOLITION BY EXPLOSIVES CE6021-RRS/unit 5 by,Shanmugasundaram.N 35 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

36. IMPLOSION Implosion i s the strategic placing of exp l osive material and timing of its detonation so that a structure colla p ses on itself in a matt e r of seco n ds,min i m i zing the physical of its immediate surroundings. The technique weakens or removes critical supports so that the building can no longer withstand the force of gravity and falls under its own CE6021-RRS/unit 5 by,Shanmugasundaram.N 36 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

37. IMPLOSION The explosives are just the trigger for the demolition. It's gravity that brings the building down. Explosives are loaded and progressively detonated on several different levels of the building so that the building structure falls down on itself at multiple points. When everything is planned and executed correctly , the total damage of the explosives and falling building material is sufficient to collapse the structure entirely, so cleanup crews are left with only a pile of rubble. CE6021-RRS/unit 5 by,Shanmugasundaram.N 37 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

38. IMPLOSION In order to demolish a building safely, each element of the implosion must be studied ahead of time. This is done by a blasting expert. The first step is to examine architectural blueprints of the building to determine how the building is put together. Next , the building is surveyed to study about the support structure on each floor . Based on this data and drawing from past experiences with similar buildings, the expert decides what explosives to use, where to position them in the building and how to time CE6021-RRS/unit 5 by,Shanmugasundaram.N 38 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

39. IMPLOSION The main challenge in bringing a building down is controlling which way it falls . Ideally, a blasting crew will be able to tumble the building over on one side, into a parking lot or other open area. This sort of blast is the easiest to execute, and it is generally the safest way to go. Tipping a building over is something like felling a tree. To topple the building to the north , the blasters detonate explosives on the north side of the building first, in the same way a tree would be chopped into from the north side if it is to fall in that direction . Blasters may also secure steel cables to support columns in the building, so that they are pulled a certain way as they crumble. CE6021-RRS/unit 5 by,Shanmugasundaram.N 39 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

40. IMPLOSION Sometimes, a building is surrounded by structures that must be preserved. In this case, the blasters proceed with a true implosion , demolishing the building so that it collapses straight down into its own footprint (the total area at the base of the building). The basic idea in implosion is to think of the building as a collection of separate towers. The blas t ers set the explos i ves s o that each tower falls toward the centre of the building. When they are detonated in the right order, the toppling towers crash against each other and all of the rubble collects at the centre of the building. Another option is to detonate the columns at the centre of the building before the other columns so that the building's sides fall inward. CE6021-RRS/unit 5 by,Shanmugasundaram.N 40 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

41. IMPLOSION Generally speaking, blasters will explode the major support columns on the lower floors first and then a few upper stories. In a 20-story building, for example, the blasters might blow the columns on the first and second floor, as well as the 12th and 15 th floors. In most cases, blowing the support structures on the lower floors is sufficient for collapsing the building, but loading columns on upper floors helps break the building material into smaller pieces as it falls. This makes for easier cleanup following the blast. CE6021-RRS/unit 5 by,Shanmugasundaram.N 41 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

42. Columns are fully loaded with explosives CE6021-RRS/unit 5 by,Shanmugasundaram.N 42 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

43. Primary charge CE6021-RRS/unit 5 by,Shanmugasundaram.N 43 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

44. Blasting machines T raditional rack-bar and Modern electronic control box CE6021-RRS/unit 5 by,Shanmugasundaram.N 44 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

45. The Scudder Homes in Newark, N.J., blasted in 1996 CE6021-RRS/unit 5 by,Shanmugasundaram.N 45 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

46. ADVANCED TECHNIQUES USING ROBOTIC MACHINES CE6021-RRS/unit 5 by,Shanmugasundaram.N 46 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

47. ADVANCED TECHNIQUES USING ROBOTIC MACHINES There is a different, specialized approach to every demolition project. Identifying the project’s unique requirements and selecting the right machine to ensure the work is done is a safe and efficient manner. Robotic machines meet these unique challenges. We have large high reach equipment that has the capability to reach some very high and awkward areas. Smaller Robotic demolisher machines to get into those tight spots and if a project has some tricky or confined spaces we have robotic equipment on hand to get the CE6021-RRS/unit 5 by,Shanmugasundaram.N 47 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

48. SAFETY PRECAUTIONS Demolition Dismantl i ng CE6021-RRS/unit 5 by,Shanmugasundaram.N 48 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

49. SAFETY PRECAUTIONS HOARDING isolates the demolition site from the public, thus preventing unauthorized access and trespassing. CE6021-RRS/unit 5 by,Shanmugasundaram.N 49 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

50. SAFETY PRECAUTIONS WALKWAYS: Walkways shall be provided for the use of the workmen who shall be instructed to use them and all such walkways shall be kept adequately lighted, free from debris and other materials. CATCH PLATFORMS In d e mol i ti o n o f e x te r i o r wall of multi storeyed structure,catch platform o f hea v y planking shall be provided to prevent injuries to the worker working below and to the public, when the external walls are more than20 m in height. CE6021-RRS/unit 5 by,Shanmugasundaram.N 50 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

51. SAFETY PRECAUTIONS CE6021-RRS/unit 5 by,Shanmugasundaram.N 51 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

52. SAFETY PRECAUTIONS The covered walkway, in conjunction with catch platform, provides additional protection to the pedestrian traffic against falling debris. CE6021-RRS/unit 5 by,Shanmugasundaram.N 52 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

53. PRO T EC T IVE SCREENS Protective screen covers shall be placed, where necessary, to prevent flying pieces from injuring the fellow workmen. Bamboo scaffolds or metal scaffolds shall be used for providing protective screens to completely enclose the building structure for retaining dust and small debris. Tarpaulin and heavy duty nets shall be used to cover the exterior face of the scaffold. The protective screens shall be secured to the scaffoldings at intervals in both horizontal and vertical CE6021-RRS/unit 5 by,Shanmugasundaram.N 53 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

54. TEMPORARY SUPPORTS Temporary supports are required to cater for the loads due the machinery used in demolition, debris accumulated, impact from fallen debris and lateral loads due to the fallen debris and wind force etc. A suitable factor of safety shall be considered. They are also provided when any part of the structure or any element being demolished is not self-supporting (or) when the temporary stability of the structure or its elements could be impaired as a result of the demolition activities. CE6021-RRS/unit 5 by,Shanmugasundaram.N 54 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

55. TRAINING AND COMMUNICATION Demolition workers, including plant or equipment operators, shall go through proper job safety training and be informed of the potential hazards by attending training sessions as well as on-the-job training. They shall be trained regarding- working at heights, working in confined spaces, working with lifting appliances, use of personal protective equipment, handling of chemicals, health hazards in demolition works and safe operating zones. CE6021-RRS/unit 5 by,Shanmugasundaram.N 55 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

56. EQUIPMENT MAINTENANCE All equipment shall be tested and examined before use. They shall be properly stored and maintained. The equipment shall be inspected daily and results of the inspection shall be recorded accordingly. A detailed safety instruction shall be provided to cater for specific situations of the project, if necessary . CE6021-RRS/unit 5 by,Shanmugasundaram.N 56 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

57. ELECTRICAL SAFETY A properly connected power source from a local electric utility supplier or a mobile electricity generator shall be utilised in demolition sites. The safety requirements given in the El e ctrici t y Regulations shall be CE6021-RRS/unit 5 by,Shanmugasundaram.N 57 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

58. FIRE SAFETY All flammable goods shall be removed from site unless they are necessary for the works involved. Any remaining flammable goods shall be stored in proper storage facilities. All furniture, timber, doors, etc. shall be removed before any welding work is performed. Fire fighting appliances shall be provided and maintained in working conditions. Emergency access to site shall be provided. CE6021-RRS/unit 5 by,Shanmugasundaram.N 58 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

59. V ibration Demolition work will cause vibration to neighbouring buildings or structures to various extent, depending on the method of demolition, which should be controlled by suitable monitoring. The most serious vibration is caused by implosion. Air Pollution Concrete breaking, handling of debris and hauling process are main sources of dust from building demolition. Dust mitigation measures, such as water spray, shall be adopted to minimise dust emissions . Burning of waste shall not be allowed . Diesel fumes generated by mechanical plant or equipment shall be controlled. CE6021-RRS/unit 5 by,Shanmugasundaram.N 59 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

60. NOISE Noise pollution arising from the demolition works due the use of powered mechanical equipment such as pneumatic breakers, excavators and generators, loading and transportation of debris , etc. Affects the works, and the sensitive receivers in the vicinity of the demolition site. Silent type equipment shall be used to reduce noise impact as much as practicable. Demolition activity shall not be performed within the restricted hours established CE6021-RRS/unit 5 by,Shanmugasundaram.N 60 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

61. DEBRIS AND WASTE HANDLING CE6021-RRS/unit 5 by,Shanmugasundaram.N 61 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

62. CHUTES Debris, waste and other materials shall not be thrown, tipped or shot down from a height where they are liable to cause injury to any person on or near the site. Existing lift shaft, light well and openings on floor may be used to convey debris down the building floors. Areas adjacent to the openings of these features used as a chute shall be barricaded when they are not in use. Warning signs shall be posted to prevent workers from entering the area. As an option, plastic chutes may be used inside the floor openings and lift wells to minimise noise and confine the falling debris. CE6021-RRS/unit 5 by,Shanmugasundaram.N 62 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

63. DISMANTELING “Dismantle" means to take apart something and can easily be use/built again. Dismantle is usually used when you take something apart in different pieces a Demolish is to damage something beyond repair or reconstruction.They overlap in that you are breaking something into pieces but demolish is mainly used when you destroy something. Example: Doors Windows Grills P.V.C pipes Bath fittings Electrical cables/wires CE6021-RRS/unit 5 by,Shanmugasundaram.N 63 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

64. Repair of structures distressed due to Earthquake (seismic) Introduction Earthqua k e cr ea te s g r eat de v ast a ti o n in ter m s of life , m oney and failures of structures . Earthqua k e Mi ti g a tion i s an i m portant fi e ld of study from a long time now. Seis m ic R e tro f it t ing i s a c o ll e c tion m itiga t ion tech n ique s f or Earthquake Engineering. It is of utmost importance for historic monuments, areas prone to severe earthquakes and tall or expensive structures . CE6021-RRS/unit 5 by,Shanmugasundaram.N 64 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

65. Seismic Retrofitting Definition It is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes . The retrofit techniques are also applicable for other natural hazards such as tropical cyclones, tornadoes ( சூறாவளி ) , and severe winds from thunderstorms. CE6021-RRS/unit 5 by,Shanmugasundaram.N 65 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

66. When is Seismic Retrofitting Needed ? The two circumstances are:- Earthquake damaged buildings, and Ear t h q uak e - vu l ner a ble ( பாதிக்கப்படக்கூடிய ) bui l d i ngs ( with n o exposu r e to severe earthquakes) Retrofit Performance Objectives Public safety only: The goal is to protect human life , ensuring that the structure will not collapse upon its occupants or passersby, and that the structure can be safely exited. Under severe seismic conditions the structure may be a total economic write-off, requiring tear-down and replacement. CE6021-RRS/unit 5 by,Shanmugasundaram.N 66 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

67. Retrofit Performance Objectives Structure survivability: The goal is that the structure, while remaining safe for exit, may require extensive repair (but not replacement) before it is generally useful or considered safe for occupation. This is typically the lowest level of retrofit applied to bridges. Structure functionality: Primary structure undamaged and the structure is undiminished in utility for its primary application. Struc t u r e unaffecte d : This le v e l of retro f it i s prefe r red for historic structures of high cultural significance. CE6021-RRS/unit 5 by,Shanmugasundaram.N 67 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

68. Need of Retrofitting in Existing Earthquake Vulnerable Buildings Buildings have been designed according to a seismic code , but the code has been upgraded in later years ; Buil d ings d e s ig n ed to m e et the m o de rn s e is m ic code s ,but deficiencies exist in the design and/or construction; Essential b u il d ings m ust b e stren g thened li k e ho s pitals, histori c al monuments and architectural buildings; Important buildings whose services are assumed to be essential just after an earthquake like hospitals; Buildings, the use of which has changed through the years; Buildings that are expanded, renovated or rebuilt. CE6021-RRS/unit 5 by,Shanmugasundaram.N 68 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

69. Problems faced by Structural Engineers are :- Lack of standards for retrofitting methods Effectiveness of each methods varies a lot depending upon parameters like type of structures, material condition, amount of damage , etc. Basic Concept of Retrofitting Up gradation of lateral strength of the structure; Increase in the ductility of the structure Increase in strength and ductility CE6021-RRS/unit 5 by,Shanmugasundaram.N 69 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

70. Earthquake Design Philosophy Under minor but frequent shaking, the main members of the building that carry vertical and horizontal forces should not be damaged; however building parts that do not carry load may sustain repairable damage; Under moderate but occasional shaking, the main members may sustain repairable damage, while the other parts of the building may be damaged such that they may even have to be replaced after the earthquake; and Under strong but rare shaking , the main members may sustain severe (even irreparable) damage, but the building should not collapse. CE6021-RRS/unit 5 by,Shanmugasundaram.N 70 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

71. Classification of Retrofitting Techniques CE6021-RRS/unit 5 by,Shanmugasundaram.N 71 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

72. Some Conventional Approaches Adding New Shear Walls Fr e quen t ly us e d f or re t r of i t t i ng o f non ductile reinforced concrete frame buildings. The added elements can be either cast‐in‐place or precast concrete elements. New e l e m ents p r e f e ra b ly b e p l a ced a t t he exterior of the building. Not preferred in the interior of the structure to avoid interior mouldings. CE6021-RRS/unit 5 by,Shanmugasundaram.N 72 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

73. Some Conventional Approaches Adding Steel Bracings An effective solution when large openings are required. Potential advantages for the following reasons: higher strength and stiffness, opening for natural light, amount of work is less since foundation cost may be minimized adds much less weight to the existing structure CE6021-RRS/unit 5 by,Shanmugasundaram.N 73 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

74. Some Conventional Approaches Adding Steel Bracings CE6021-RRS/unit 5 by,Shanmugasundaram.N 74 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Fig: RC Building retrofitted by steel bracing

75. Some Conventional Approaches Jacketing (Local Retrofitting Technique) Most popular method for strengthening of building columns T ypes-1. S t eel jac k et, 2. Reinforced Con c re t e jac k e t, 3. Fibre Reinforced Polymer Composite(FRPC) jacket Purpose for jacketing: To increase concrete confinement To increase shear strength To increase flexural strength CE6021-RRS/unit 5 by,Shanmugasundaram.N 75 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

76. Some Conventional Approaches Jacketing CE6021-RRS/unit 5 by,Shanmugasundaram.N 76 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Fig: Column Jacketing Fig: Beam Jacketing

77. Retrofit of Structures using Innovative Materials Current research on advanced materials has mainly concentrated on FRP composites. Studies have shown that externally bonded FRP composites can be applied to various structural members including columns, beams, slabs, and walls to improve their structural performance such as stiffness, load carrying capacity, and ductility. CE6021-RRS/unit 5 by,Shanmugasundaram.N 77 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

78. Effectiveness of FRPC as a Retrofitting Material CE6021-RRS/unit 5 by,Shanmugasundaram.N 78 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Fig: A 3-D Model of a Building (a) Wall Stresses before Retrofitting (b) After installation of Steel Window frames (c) Additional FRP Retrofitting Fig: A Retrofit Application combining Conventional and Composites Retrofitting

79. BASE ISOLATION TECHNIQUE

80. TECHNIQUES OF ASEISMIC DESIGN Structural Configuration (IS 4326 : 1893) Lateral Strength (IS 13920 :1993) Good Ductility Light Weight Mass unit-5, by, R.Pandi

81. Base Isolation Techniques Structural Configuration Lateral Strength unit-5, by, R.Pandi

82. Base Isolation Techniques Seismic base isolation is emerging as on alternative approach for EQ protection of structure. The basic concept in this approach is to uncouple a structure from the ground by interposing a flexible element/ bearing between the structure and foundation. Many building have been constructed on some type of rubber bearing. The aim of base isolation is to minimize the energy that is transferred from ground motion to the structure by buffering it with a bearing layer at the foundation which has relatively. unit-5, by, R.Pandi

83. Need for Base Isolation Building is located in a high seismic intensity Zone. Building should be operational in post earthquake period such as hospital, school, water tank etc.. Limitations exist with lateral forces restraining system or other masonry or precast system. Minimize the damage to primary and secondary structure member. Cost economics of the structure with or without isolates. unit-5, by, R.Pandi

84. RESPONSE OF BUILDING unit-5, by, R.Pandi

85. RESPONSE OF BUILDING unit-5, by, R.Pandi

86. Types of Base Isolation Devices Elastomeric Bearings High Damping Bearings Lead Rubber Bearings Flat Slider Bearings Curved Slider Bearings or Pendulum Bearings Ball & Roller Bearings unit-5, by, R.Pandi

87. Types of Base Isolation Devices Elastomeric Bearings High Damping Bearings unit-5, by, R.Pandi

88. Types of Base Isolation Devices Lead Rubber Bearings Flat Slider Bearings unit-5, by, R.Pandi

89. Types of Base Isolation Devices Curved Slider Bearings or Pendulum Bearings Ball & Roller Bearings unit-5, by, R.Pandi

90. TYPES OF DAMPERS Metallic Dampers or Yielding Dampers Friction Dampers Viscous Dampers unit-5, by, R.Pandi

91. MEtaLlic Dampers or Yielding Dampers unit-5, by, R.Pandi

92. Friction Dampers unit-5, by, R.Pandi

93. Viscous Dampers unit-5, by, R.Pandi

94. Repair of structures distressed due to Fire CE6021-RRS/unit 5 by,Shanmugasundaram.N 94 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Introduction Windsor Tower in Madrid, Spain a modern high- rise building (29 floors) exposed to fire in 2005 and lasted 25 hours. The building had a bearing structure made of: R e in f orced c o ncre t e: slabs, shear wall, cores and interior columns Steel: perimeter columns According to NFPA report 2015 1 “Structure” fire reported every 63 seconds. 1 “Highway” fire reported every 181 seconds . National Fire Protection Association  (NFPA)

95. Fire Damage Concrete Damage Mechanisms: Surface Cracking / Crazing Chemical Decomposition Micro cracking and Spalling Temperature Effect on: Colour of Concrete Compressive Strength of Concrete ( f’c ) Modulus of Elasticity (E) Steel Reinforcement CE6021-RRS/unit 5 by,Shanmugasundaram.N 95 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

96. Fire Damage – Damage Mechanisms (1) Surface Cracking / Crazing Crazing : network of fine surface cracks in concrete which usually occurs in early ages of concrete due to shrinkage of the surface layer. Repairing of cracks is essential when the chloride ion exists in the concrete itself or its surrounding environment. Crazing and surface cracks are caused by: low humidity fire thermal incompatibility hot sun drying out Size of cracks: Depth < 3 mm (1/8”) Diameter of grids of < 50mm (2”) CE6021-RRS/unit 5 by,Shanmugasundaram.N 96 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

97. Fire Damage – Damage Mechanisms (2) Chemical Decomposition The raise in temperature during fire will lead to water evaporation and dehydration in cement paste . This will cause decomposition of calcium hydroxide and calcium aluminates in concrete . Decomposition occurs after evaporation of free water and capillary water and will be initiated by the loss of physically bound water. The colour of concrete will turn into pink as a result of this mechanism CE6021-RRS/unit 5 by,Shanmugasundaram.N 97 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

98. Fire Damage – Damage Mechanisms ( 3) Micro cracking and Spalling Spalling : the small cracks and separation of surface layers of concrete due to rapid change in temperature (such as fire) and leads to exposition of steel reinforcement and its rapid deformation due to heat. Spalling caused by high temperature can be: full destruction at slow rates sudden exploding of smaller or larger pieces of concrete with thickness less than few centimeters at early ages of heating. Spalling of the concrete cover during a moderate fire after 1906 San Francisco earthquake CE6021-RRS/unit 5 by,Shanmugasundaram.N 98 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

99. Fire Damage – Damage Mechanisms (3) Micro cracking and Spalling “Water Clog” theory describes the Spalling process as below: Rapid evaporation of free near-surface water, Vaporizing and moving of the internal moisture toward the cooler concrete core, Condensation of water vapor as it cools, Resistan c e of the low p e r m eabi l i t y con c r e te la y e r to w a t e r t ransf o rm a tion towards cooler core, Development of water pressure in the pores and capillaries, Reaching the critical point in which water pressure exceeds the tensile strength of concrete, Concrete spalling and microcracking CE6021-RRS/unit 5 by,Shanmugasundaram.N 99 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

100. Fire Damage – Damage Mechanisms- Spalling CE6021-RRS/unit 5 by,Shanmugasundaram.N 100 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

101. Fire Damage – Temperature Effect (1) Colour of Concrete Due to the chemical and physical changes and dehydration of the cement paste, the colour of the concrete will vary during a fire, depending on the fire temperature. Colour Change can be a used as an indicator of the exposure temperature and thus, the corresponding fire damage of concrete can be estimated. According to this table, the concrete will be considered unaffected up to around 300⁰C (550⁰F). CE6021-RRS/unit 5 by,Shanmugasundaram.N 101 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

102. Fire Damage – Temperature Effect (2) Compressive Strength of Concrete The compressive strength of concrete will not change up to 300⁰C, however, this is threshold temperature for speed of strength loss in mortars, which it will become more rapid after that. Although the f’c will not drastically change till 300⁰C, the strength of the concrete will significantly reduce by 30-40% due to internal cracks caused by thermal expansion. The strength of concrete will not be recovered after cooling. CE6021-RRS/unit 5 by,Shanmugasundaram.N 102 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

103. Fire Damage – Temperature Effect (3) Modulus of Elasticity of Concrete Up to 300⁰C, the loss in modulus of elasticity is in the same order of loss of concrete strength, about 40%. The loss of E around 550⁰C, is about 50%. (4) Steel Reinforcement The yield strength of steel reinforcement can be reduced up to 50% of its initial value when the fire temperature rises to 600⁰C. The steel strength can be completely recovered when the rebar cools down from 450⁰C - 600⁰C, depending on the steel rebar manufacturing type. T he mo d u l us o f e l astic i t y o f ste e l i s a l so re d uc e d w ith ra i se in temperature, as expected. CE6021-RRS/unit 5 by,Shanmugasundaram.N 103 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

104. Evaluation Methods Verifying the Safety of the Structure Preliminary Investigation Cleaning Physical Appearance Fire Intensity Observation Field Tests Detailed Investigation: Destructive Methods Non- Destructive Tests (NDT) Load Testing CE6021-RRS/unit 5 by,Shanmugasundaram.N 104 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

105. Evaluation Methods CE6021-RRS/unit 5 by,Shanmugasundaram.N 105 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Preliminary Investigation: Cleaning the structure Physical appearance Estimation of fire intensity Observations and other in-site information . Melting temperature of different material . Other material's condition Field Tests: . Ordinary hammer . Chisel or screwdriver Is the Structure Safe to Enter? Data on structure Data from fire department Informal interviews Observations and other in-site information Detailed Investigation: - Destructive Tests . Coring . Petrographic . Differential Thermal Analysis (DTA) . Micro Hardness - Non-Destructive Tests (NDT) . Pulse-Velocity (Soniscope) . Impact-Echo . Magnetic and Microwave (Radar) . Peneteration Resistance (Windsor Probe) . Rebound (Scmidt) Hammer Load Testing: Before repair After repair

106. Evaluation Methods – Preliminary Investigation (1) Cleaning Smoke deposits and soot usually hides the spalling and cracks due to fire and cleaning of the structure will result in more clear observations and more accurate identification of the deflected and distorted members. Cleaning can be done using various methods such as water blasting, dry ice blasting, chemical washing and etc. These methods might cause secondary damages to the structure and the dry ice blasting or chemical washing is the safest method The loss of E around 550⁰C, is about 50%. (2) Inspecting Physical Appearance of Structure (Visual Inspection) The cracks, spalling , deformations, misalignments, distortions and exposure of steel reinforcements is documented The deflection and geometry of some suspicious members are measured and documented CE6021-RRS/unit 5 by,Shanmugasundaram.N 106 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

107. Evaluation Methods – Preliminary Investigation (3) Fire Intensity Fire intensity can be estimated by observing the building contents and the post-fire condition of the other materials. K n o w i ng the me l ting p o int o f some mat e ri a l a nd i n s pe cting the b u il d i ng content, one can estimate the local and maximum fire temperature. The debris condition in different fire temperatures is an additional source for estimating the fire temperature. CE6021-RRS/unit 5 by,Shanmugasundaram.N 107 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

108. Evaluation Methods – Preliminary Investigation (4) Field Tests When the previous phases of preliminary investigation will not reveal enough information to evaluate the fire’s severity and to decide about future activities and further examination, simple on-site testing methods are used as adjunct to visual assessment of the damaged structure . Striking hammer to the c oncrete material and taking the sounding is one of the common methods. In this method the material will be good and hard when it tends to be solid and “ring” and the weekend concrete tends to be “dull thud” and hollow. Use of chisel is another method which is used to inspect the softened regions on the surface of the concrete CE6021-RRS/unit 5 by,Shanmugasundaram.N 108 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

109. Evaluation Methods – Detailed Investigation (1) Destructive Test Methods These methods will require more time and effort rather than NDT test methods and caution is necessary during the sampling process. They will provide more detailed information about the strength and mechanical properties of the material as well as the depth of the fire and cracks location. Destructive test methods are generally performed either in field or lab and there are various methods available for this purpose. Coring It i s m a i n ly us e d to de term in e the po ison r a ti o , m odu l u s o f e l a stic i ty a nd compressive strength of the concrete . The samples will be tested in the lab. Petrographic Test Coring This test is a deterministic testing method in determining the fire damage depth in concrete and is usually performed on core sample s. Petrographic test will also offer valuable information about the location and orientation of the cracks and microcracking , loss of rebar-cement bond and cement-aggregate bond, dehydration, carbonation depth, water/cement ratio, etc. CE6021-RRS/unit 5 by,Shanmugasundaram.N 109 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

110. Qualification by Testing The most common test method for determining fire resistance in the United States is the ASTM Standard E 119 Test Methods for Fire Tests of Building Construction and Materials . CE6021-RRS/unit 5 by,Shanmugasundaram.N 110 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

111. REHABILI T ATION Introduction Decision Making Process- Need of Rehabilitation Selection of Repair Materials for concrete Rehabilitation and Retrofitting Methods. Guidelines for Terms and conditions for repairs. Schedule for special Items of works. Specifications for Structural Repair work CE6021-RRS/unit 5 by,Shanmugasundaram.N 111 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

112. Rehabilitation Methods Keeping the objective in view, a rehabilitation strategy has to be adopted. Based on the evaluation and availability of various method of repair and the site condition. To ensure well-being of the structure and security from further deterioration , priority should be given to rehabilitation of structural shortcoming. CE6021-RRS/unit 5 by,Shanmugasundaram.N 112 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

113. List of Rehabilitation Methods Surface Cleaning and smoke removal Breaking Out : replacing the damage concrete + undisturbed reinforcement Ferro cement : Using mesh + Plasticizers +polymers for sealing pores Plate Bonding : MS plates+ epoxy glue for bonding + Bolting. Shotcrete : Pneumatically applied concrete or mortar placed directly on to a surface Epoxy bonded concrete ( fresh concrete +resin bond coat on hardened surface ( depth 40mm or more) may be reinforcement / shear keys etc , Silica Fume concrete : Portland cement with silica fumes in case High strength requirement mostly used with super plasticizers. RCC jacketing :Composite action with old and new : ensure old concrete is good. CE6021-RRS/unit 5 by,Shanmugasundaram.N 113 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

114. Breaking Out Technique CE6021-RRS/unit 5 by,Shanmugasundaram.N 114 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Hydro Blasting for concrete removal Breaking out- slab

115. List Of Rehabilitation Methods CE6021-RRS/unit 5 by,Shanmugasundaram.N 115 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 Jacketing of Column

116. FPR- Fibre reinforced polymer It is a synthetic material in which polymer matrix is reinforced with fibres. Most commonly used fibres are glass, carbon or aramid light in weight exhibits high strength and stiffness It is non corrosive CE6021-RRS/unit 5 by,Shanmugasundaram.N 116 /35 SNS COLLEGE OF ENGINEERING 3/5/2019 FRP plate application beneath the beam FRP sheets wrapped around the Column

117. Guidelines Prior to design: The design should meet the demand of local building regulations and it needs approval from the local authority. Also design of the repair sections should comply with the current design codes. As in some cases the priory design of the structure may have been design to the codes which are revised in the meantime. So the code used in the past were out of date. In some cases it can be inferred from the investigation that the structure was deficient in the original design. Original design should be obtained as it will help to plan strategy to assess the “as built” properties of the structure. CE6021-RRS/unit 5 by,Shanmugasundaram.N 117 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

118. Typical Examples Of Column Repair By Guniting CE6021-RRS/unit 5 by,Shanmugasundaram.N 118 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

119. Slab Strengthening : Concrete Overlay CE6021-RRS/unit 5 by,Shanmugasundaram.N 119 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

120. Beam strengthening : concrete overlay And section enlargement CE6021-RRS/unit 5 by,Shanmugasundaram.N 120 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

121. Conclusions The decision about whether to rehabilitate and retrofit the structure or to reconstruct after demolishing the structure is influenced by many factors like technical, financial, safety, physical, Etc. Repair strategies should be planned based on the results of evaluation phase and also various available rehabilitation methods. Current building design code specifications should be considered. CE6021-RRS/unit 5 by,Shanmugasundaram.N 121 /35 SNS COLLEGE OF ENGINEERING 3/5/2019

122. SNS COLLEGE OF ENGINEERING 122 /35 CE6021-RRS/unit 5 by,Shanmugasundaram.N THANK YOU 3/5/2019