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demolition techniques
- 1. Comparative Study Of Various Demolition Techniques
- 2. GOVERNMENT ENGINEERING COLLEGE VALSAD Prepared By :- Guided By:- Prof. D. J. Patel Team ID :- 65396 Sr. No. NAME Enrollment No. 1 Neha Jerambhai Bhanushali 130190106007 2 Harsh Chandravadan Rana 130190106048 3 Moxesh Hitesh Shah 130190106053 4 Shiraz Hanif Solanki 130190106055
- 3. ABSTRACT Usually the life period of concrete structures is 40 to 90 years. Existence of the structure is very dangerous to the occupants and surrounding buildings after the design life period which may lead to severe impacts and a cause of many deaths. These structures often meet with disasters, city reconstruction and higher residence demand due to increasing population which leads to reconstruction or demolition of existing structures.
- 4. INTRODUCTION Definition “Demolition means destruction, tearing down, breakup, removal of whole or a part of any structure with the help of some equipments or other method in a controlled manner with a legal procedure and consent of the local authority.” Demolition is generally classified as A. Commercial demolition B. Military demolition
- 5. AIM AND OBJECTIVES AIM:- Suggesting an ideal demolition technique that can be adopted in the given condition, considering the demolition factors affecting it. OBJECTIVES:- To compare different demolition techniques. To get the knowledge of their impacts on environment. To study the preplanning for the control execution of demolition work. To find major factors affecting the controlled demolition. To have an overview on the demolition of special structures.
- 6. SCOPE OF WORK Upcoming major projects like highways, railways, etc. Demand for modernization and improve comfort. Illegal construction. Redevelopment of inner urban areas. Post earthquake activities. Building damaged in fire accidents. Brownfield expansion instead of Greenfield.
- 8. LITERATURE REVIEW PLAN OF WORK PLANNING DESIGNNING EXECUTION Site Knowledge Health and safety risk assessment Prequalification and selection of specialist contractor Utilities encountered Structural survey Stability report including calculations Demolition plan Precautionary measures Sequence of demolition Site supervision and inspection Safety measures
- 9. 1) Conventional method 2) Mechanical method 3) Electric method 4) Microwave method 5) Sonic wave method 6) Advanced robotics method 7) Chemical method 8) Hydraulic jet method 9) Thermal lance method 10) Stitch drilling method METHODS OF DEMOLITION
- 10. Conventional Methods Sledge hammer Rotatory hammerChipping hammer
- 11. Equipments in Conventional Method Demolition hammer Pavement breaker Pneumatic hammer
- 12. In general, the following sequence shall apply: 1) Utilities disconnection. Electricity, plumbing water lines, drainage connections etc. 2) All cantilevered structures, canopies, verandahs and features attached to the external walls shall first be demolished prior to demolition of main building and its internal structures on each floor 3) 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
- 13. 4) Demolition of the floor slabs shall begin at mid span and work towards the supporting beams. 5) Floor beams shall be demolished in the order of cantilevered beams, secondary beams and then main beams. 6) Non-load bearing walls shall be removed prior to demolition of load bearing walls. 7) Columns and load bearing walls shall be demolished after removal of beams on top.
- 14. Mechanical Methods High reach arm Adopted when the demolition work exceeds by 20m in height. It consists of three parts- 1) Base tank 2) Long arm 3) Primary tool attached to the arm
- 16. Hydraulic Impact Hammer Hammer Produce a Repeated a Impulse to break the structure
- 17. Hydraulic Concrete Crusher Produce tremendous amount of force to cut the steel as well as concrete structure
- 18. Hydraulic Splitter Apply lateral forces against inside of the hole drilled into the concrete.
- 19. Wrecking Ball Destruction is done by the impact energy. Steel ball (weighing up to 6500 Kg) suspended from the crawler crane. Can’t be used on Steel structure. Less Control On Moving Ball.
- 20. Pusher Arm Pusher arm attached, apply horizontal thrust to structure to be demolished. Adopted for height is less than 15m . 2/3 height of structure < point of application of force < 600mm from top of structure.
- 21. Calm Shell Calm shell progressively bites the structure from top to bottom either by deliberate collapse or wire rope pulling. The clam shell shall be operated not less than 1 m above the structure being demolished.
- 22. 1) The sequence of demolition by machine is typically the same as the top down manual method, except that most of the demolition is done by mechanical plant. 2) The demolition begins with the lifting of the mechanical plant on to the building top floor. 3) When rope or tie wire is used for pulling, the workers shall be protected or stay away from the area within reach of the rope or tie wire. 4) Adequate propping shall be installed at floor levels below the working floor to safely support the operation of the mechanical plant. 5) The movement of the mechanical plant shall only be within the propped area. The propped areas shall be suitably marked. 6) 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.
- 23. 7) The mechanical plant shall be lifted onto the roof of the building by the use of mobile crane or other appropriate means as approved. 8) 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. 9) The slope of the ramp shall be not steeper than 1.75 to 1 or as recommended by the machine manufacturer. 10) As an alternative, the machine may also be lowered to the next floor by the use of mobile crane
- 26. In the electrical method, electrical heating of concrete is done to remove concrete cover by generating a continuous wide crack over reinforcing bar. Thermal expansion of bar occurs when low voltage direct current or large current is applied and thus creating tensile stresses in concrete cover. Electric method This method is based upon the principle of raising the temperature of concrete by microwaves which results in breaking of concrete due to the generation of stress. Main disadvantage – jamming of communication and harmful effects on human beings. Sonic Method Demolition of large buildings which are to be turned down by application of high intensity sonic energy. Main principle that the structure is demolished at resonance frequency. Microwave Method
- 27. Advanced techniques using robotic machines 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. 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 job done.
- 28. Chemical methods Explosive The basic concept of blasting is removing the support element of the building at a certain point and the section of the building above the point will fall down. The explosives are just trigger for demolition and it is gravity that brings the structure down.
- 29. Soundless Chemical Demolition Method Powdered chemical will swell or expand continuously when placed in water. Main component used here is calcium oxide which when mix with water forms calcium hydroxides and causes increase in volume Main advantage of SCDAs is it does not generate noise, vibration, toxic fumes or flying debris
- 30. Higher pressure foam is inserted through an injection barrel into the bottom of drilled hole in concrete. The foam posses high viscosity and stored energy which results in an efficient and controlled destruction. Control Form Injection
- 31. Hydraulic Jet Method Water jets stream with flow rate of 95-150 litres/s is pumped at high pressure of about 800 to 1300 kg/cm2 directed at the concrete surface to remove the cement matrix and wash out the aggregate.
- 32. Thermal Lance Thermal lance is used for cutting reinforced concrete in which temperature ranges up to 2000-4000˚C. Thermal lance is a tool that burns iron in the presence of pressurise oxygen to create very high temperature for cutting.
- 33. Stitch Drilling Diamond drills have been used to core holes in concrete up to 54 inches in diameter. Larger holes can be made by drilling a series of overlapping small holes in a circle or straight line, called stitch drilling. It is generally used in the industries where retrofitting is the major concern.
- 34. ENVIRONMENTAL IMPACTS Air pollution Water pollution Noise Vibration Occupational health