International Journal of Emerging Technology and Advan - PDF document

International Journal of Emerging Technology and Advanc ed Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 3 , Issue 4 , April 2013 ) 396 B uilding D emolition: Ground to Earth I mportant as C onstruction M.G.Bhandari 1 , V. K. Kulkarni 2 , R.K.Malviya 3 1 M.G.Bhandari Asst.Prof.J.T.M.C.O.E. Faizpur 2 V.K.Kulkarni Lecturer J.M.C.T.Polytechnic , Nasik 3 R.K.Mal viya Assc.Prof.J.T.M.C.O.E, Faizpur Abstract — Demolition of a ny structure is a ground to earth technique which means destroying down or falling down of a building with the help of equipments , machineries, explosives or with manual techniques without affecting the surrounding . D emolition is a simple process for small buildings or houses . The building is brought down either manually or mechanically using large hydraulic equipment: elevated work platforms, cranes, excavators or bulldozers. D emolition work is to be performed safely and with number of dif ferent steps involved before and during the execution of a demolition process. The various steps involved before the demolition process includes surveying the site of demolition , removal of hazardous materials if any , and preparation of demolition plan wit h techniques to be implanted , stability report and the precautionary safety measures to be taken for the workers and the surroundings . E quipments used for these demolition activities are like sledge hammer or rammers ; excavators, bulldozers, tearing balls etc. and main explosives used are like dynamites and RDX. When explosive are used for the demolition, it is known as Implosion , which is generally preferred for high and tall towers. I. I NTRODUCTION Any demolition activity t o start with , there are many steps that need to take place forehand including but not restricted to performing asbestos abatement, removing hazardous or regulated materials, obtaining necessary permits from the authority, submitting necessary notifica tions, disconnecting utilities, and deve lopment of site - specific safety and work plans for the workers as well as the surroundings with a detail planning of every stage with a working strategy. We know every structure is designed for a specific life period generally 100years . The existence of t he structure after the service life period is over is very dangerous to its occupants and surrounding buildings .The building act usually based on the provisions that enable in charge authorities to control demolition works for the protection of public saf ety with their belongings and to ensure adjoining premises and the site are made good on completion of the demolition. Greenhouses, conservatories, prefabricated garages and sheds do not require permission to be demolished. II. D EMOLITION Demolition of any structure is the process of destroying down or falling down or collapsing down of large buildings after its useful life period with the help of some equipment or other method with a legal procedure followed by the consent of the local authority. Buildings when demolished with the help of explosions a re called as an implosion a systematic technique of bringing down the structure. Every civil engineering structure is designed for a certain life period generally 100 years . After that the existence of a structu re is very dangerous and unstable which may cause a severe impact and be a cause of many deaths . So removal of such structures with proper safety measures has got great importance. There are different steps involved before and during the time of a demoliti on activity. They are described as follows. III. P RE - P LANNING O F D EMOLITION A CTIVITY The different steps before the start of a demolition process are: A . Surveying of site B . Removal of hazardous materials from the site C . Preparation of plan along with strateg y to implement D . Stability report from local authorities E . Safety measures to be used A Surveying of Site S tudy of different parameters with different views of the structure and its surroundings with structural point of view is carried in surveying . T wo t ypes of surveying which are mainly conducted. They are 1 . Building surveying 2 . Structural surveying International Journal of Emerging Technology and Advanc ed Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 3 , Issue 4 , April 2013 ) 397 A.1 Building surveying It includes the following , (a) Record Drawings Prior to the Building Survey, the existing record plan, including layout plan showing various adjoining properties, pedestrian walkway, roads and street, etc. shall be shown and studied . (b) Survey of Buildings The Building Survey shall cover the following: (1) The construction materials used and its quality ; (2) The existing use an d, if possible, the past uses of the building prior to demolition with maximum utilization ; (3) The presence of wastewater, hazardous materials, matters arising from toxic chemicals, flammable or explosive and radioactive materials, etc. and possi ble prese nce of materials which can c reate air pollution and soil contamination; (4) D angerous areas, e.g., abnormal layouts, (5) Surrounding properties and site conditions, such as the presence of slope and retaining wall, wall supporting ground, illegal struct ures, bridges, underground railway and its above ground structures, including entrances, vent shafts, distribution substations, plant rooms, overhead railway structures, overhead cables or guy wires, and other utility Service connections should be conside red ; (6) Drainage conditions and possible problems on water pollution, flooding and erosion, (7) Common facilities with adjoining building, including common staircases, walls, and possible effect on it, such as self - enclosed walls to the adjoining build ings, (8) Hoarding and covered walkway requirements; (9) Adjoining pedestrian walkway and vehicular traffic conditions; (c) Hazardous Materials on and in surrounding (1) Unless and until the Building Survey found that no obvious hazardous material is pres ent in the building, the Authorized Person shall carry sampling and testing for the hazardous materials; (2) W hen hazardous materials e.g., asbestos containing materials, or petroleum, are present, they shall be removed and cleaned/disposed of according to the statutory requirements administered by the Environme ntal Protection Department . (3) W hen the site has previously been used to store chemicals, and other dangerous goods, soil contamination assessment shall be required at pre - demolition stage and/ or po st - demolition stage; and (4) W hen the site has previously been used to store explosives, special procedures to ensure no explosives remain on site will be required. A . 2 Structural surveying (a) Record Drawings Before Structural Survey, the existing recor d layout, structural plans and structural details shall be studied carefully . The Registered Structural Engineer or the concern local authority shall check the presence of unusual detailing that may cause abnormal structural behavior during demolition, e.g ., upward anchor of tensile reinforcement in cantilevered structures. If existing record plans are available, these plans shall be used as reference and preferably be brought along with the Structural Survey. (b) Survey Items The Structural Survey shall co ver the following: (1) The structural materials used with quantity ; (2) The original structural system employed in the design; (3) The method of construction; (4) Any disintegration and deterioration on any structural elements; (5) The structural condition s of adjoining structures (6) The presence of continuous structures that may be affected by the demolition; (7) The presence of basements, underground tanks or underground vaults; (c) Special Structures The Structural Survey looks at the following: (1) Th e correctness of structural data available; (2) The presence of any unconventional structural elements which may require special attention and well - defined modification procedures; (3) The possibilities of structural modification to enable efficient demoli tion traffic during demolition; and (4) Any limitation on shoring and other temporary supports. (d) Investigation and Testing at site W hen no structural details are availa ble, the structural survey include s on site measurement and finds any structural fram ing as much as practicable, performing tests and exposing some key structural elements to facilitate checking on present structure. This allow s the development of procedures that ensure the stability of the building at all stages during demolition. International Journal of Emerging Technology and Advanc ed Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 3 , Issue 4 , April 2013 ) 398 B. R emoval of H azardous M aterials from site H azardous materials if any , such as asbestos containing materials, petroleum contamination and radioactive contamination , etc exist in the building, further investigation and removal of such hazardous material or co ntamination b y experts shall be done . B.1 Asbestos Containing Material if any on site Experts shall be employed to take samples and such samples shall be tested for asbestos containing material. W hen asbestos containing materials are found , expert contract or shall be employed to remove such asbestos containing material. B.2 Presence of Soil Contamination Material W hen possible soil contamination material is present, experts shall be employed to prepare soil contamination test proposal and submit such propo sal to the Environmental Department for comment. Upon agreement by the Environmental Department, and completion of the tests, a Soil Contamination Assessment shall be submitted to the Environmental Department for acceptance. W hen remedial works are require d, the remedial proposal has to be submitted to the Environmental Department for consent approval before implementation of such remedial works. C Preparation of plan and strategy A Demolition Plan and strategy shall include the following: C. 1 A detail p lan showing : (a) The building location to be demolished; (b) Topography of the site with its ground level contours and sections of the slopes and ground supported by the building where appropriate in detailed ; (c) Details of ground removal and/or backfilli ng; and (d) The distances from the building to be demolished to its adjacent buildings, streets, structures and significant street furniture. C. 2 A detail layout plan of all floors of the building to be demolished, showing: (a) The resident usage of the fl oors; (b) The structural support; (c) M aterials of construction with quantity ; (d) B uilding Condition e.g. the degree of deterioration; and (e) The relationship of the building to be demolished with surrounding properties affected by the demolition, which include all adjoining buildings and unauthorized structures, C. 3 A Detail plan showing the structural arrangement C onstruction of all unconventional structural elements, such as prestressed concrete structures, precast concrete members, stressed skin s tructures, steel framed structures, hangers, han ging ties, trusses or girders, deep beams, long span beams (greater than 1 0 m), arches shall be studied C.4 A Detail plan showing the steps for the demolition D etailed sequence of demolishing particular stru ctural members; and the method of demolition to be adopted including the restrictions on the use of any particular type of equipment if any shall be highlighted . W hen powered mechanical plants and equipment are used, a plan showing the route of movement of powered mechanical plants and equipment including the method of lifting mechanical plant, where necessary, onto the top floors of the structure; any structural alterations required to suit the demolition . C.5 A plan showing all precautionary and emergenc y measures for the protection of the public including hoardings, covered walkways, platforms, scaffolding , protective screens and safety nets; C.6 A plan showing the proposed shoring and precautionary measures for all affected adjacent buildings, slopes, r etaining structures and services at each stage of the demolition works; C. 7 A plan showing the proposed shoring and temporary support to be provided to the building to be demolished; C. 8 A plan or descriptive notes on the proposed methods for handling and disposal of debris including (a) The permissible temporary accumulation of building debris at upper floors and at ground floor; (b) Method of handling demolished building debris; (c) The routing and movement of debris from each floor to on grade holding ar ea prior to leaving the site; (d) Means of transportation of debris off the site; (e) Time and frequency of debris disposal off site; D Detail Stability R eport According to Building (Administration) Regulation, the Demolition Plan must be accompanied by a Stability Report with supporting calculations. The Stability Report shall include the following parts: (1) A report on the stability of the building to be demolished during all stages of demolition; International Journal of Emerging Technology and Advanc ed Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 3 , Issue 4 , April 2013 ) 399 (2) In the case when powered mechanical plants or equi pment are used, a report on the stability of the building with supporting calculations to demonstrate that the use of the plants and equipment will not render inadequate the margin of safety of, or cause damage to any building, structure, street, land and services; (3) In the case when powered mechanical plants or equipment are used, structural calculations for all temporary supports and bracings; (4) A report on the stability of neighboring buildings, adjoining properties. (5) In the case when temporary or permanent supports are required to these neighboring buildings, adjoining properties, and party walls, structural calculations for these temporary and permanent supports; and E Safety M easures E.1 Training to workers Demolition workers, including plant or equipment operators, shall be given proper job safety training and be informed of the hazards by attending training sessions as well as on - the - job training. Such type of trainings shall be constantly carried so as to create awareness in workers E.2 Mainte nance of e quipment from time to time Proper maintenance of a ll equipment shall be carried and tested and examined before use. They shall be properly stored and maintained time to time by experts and technicians . The equipment shall be inspected daily and r esults of the inspection shall be recorded accordingly with the consent of the expert’s periodically . A detailed safety instruction shall be provided to cater for specific situations of the project, if necessary. E.3 Electrical appliances Safety A properly connected power source from a local electric utility supplier or a mobile electricity generator shall be utilized in demolition sites with an emergency services kept in hand in case if required . The safety requirements given in the Factories and Industria l Undertakings (Electricity) Regulations shall be adhered to with precautionary measures kept ready to hand . E.4 Fire and fire extinguishers All goods which are flammable shall be removed and cleared from site unless they are necessary for the works. R emai ning flammable goods if any shall be stored in proper storage facilities with proper attention of the expert in charge . All furniture, timber, doors, etc. shall be removed before any welding work is performed. Fire fighting appliances along with enough ma n power shall be provided with appliances maintained in working conditions. The Construction Site (Safety) Regulations require the contractor to maintain in good condition and free from defects all fire fighting appliances provided in such construction sit e. E.5 Occupational Health a priority H ealth of workers on site shall be properly protected in accordance with the regulations of the Factories an d Industrial acts and the Occupational Safety and Health acts , as well as various acts by State of Maharashtra with particular attention to the following areas: (A) Exposure to Dust; (B) Chemical Exposure; (C) Heat Stress and Ventilation; (D) Noise Exposur e; (E) Medical and First Aid Facilities; (F) Sanitation; and (G) Occupational Diseases. E.6 Emergency Exit in Demolition Sites for safety Emergency exits shall be provided during building demolition. In case of any emergency evacuations, the emergency exit will serve as a lifeline for transportation of injured workers. A minimum of one exit route shall be maintained and designated as the emergency exit at all times during the demolition. Adequate lighting and fire extinguishing equipment shall be provided. Emergency exit shall be properly protected, free of obstruction, and properly marked with exit signs or other indications to clearly show the route. All workers shall be informed about the exit route. E.7 Vibration and its Effect Demolition work cause s vib ration to surrounding buildings or structures to various extents, depending on the method of demolition adopted . The most serious vibration is caused by implosion. The effect of vibration caused by implosion is categorized as follows: - 1. Permanent ground distortion produced by blast - induced gas pressures; 2. Vibratory settlement of foundation materials; 3. Projectile impact (i.e. blast fly rock); and IV. M ETHODS O F D EMOLITION There are two types of demolition A . Non explosive demolition method B . Explosive demolition method International Journal of Emerging Technology and Advanc ed Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 3 , Issue 4 , April 2013 ) 400 A Non explosive demolition method D emolition of a structure done with some or other equipment without use of any explosive . Different equipments used for the demolition activity are A.1 Sledge H ammers and rammers A sledge h ammer and rammers , equipment used for removing a stone wall or a single column. It consists of a long stem with a metallic head. It is used to give impacts on the surfaces and that cause the demolition of structure. It cannot be used for removal of large b uildings. A.2 Excavators and Bulldozers Hydraulic excavators may be used to topple one - or two - story buildings by an undermining process. The undermining process means erode the base or foundation, i.e., dig or excavate beneath the foundation so as to make it collapse. The strategy of excavation is to undermine the building while controlling the manner and direction in which it falls. The demolition project manager will determine where under mining is necessary so that the building is pulled into the desired manner and direction. Safety and cleanup considerations are also taken into account in determining how the building is undermined and ultimately demolished. A.3 W recking B alls or Spilling Balls In case of build ings have greater heights 5 onwards story mac hineries like normal excavators and bulldozers are not sufficient. In such cases crane with wrecking balls or spilling balls are used to perform the demolition activity. The wrecking balls are steel balls hanging from a steel rope w hich is attached to the crane. This method is more effective only for high rise masonry structures because of the uncontrolled backward movement of steel ball after the impact on the wall surface. Now adays this method is not commonly used because of this uncontrolled behavior of wrecking balls which may cause some other accident . B Explosive D emolition method The basic idea of explosive demolition is quite simple , easy and fast . If we remove the support of the structure of a building at a certain point, the section of the buil ding above the point will come down on the part of the building below that point from where it is exploded . If this upper section is heavy enough, it will collide with the lower part with sufficient force to cause significant damage. The explosives are jus t trigger for the demolition. It’s gravity that brings the building down. Demolition blasters or blasting expert (“Blasting expert” means a person who is the holder of a valid mine blasting certificate.) load explosives 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 cleanu p crews are left with only a pile of rubble. The main challenge and risk in bringing a building down is controlling which way it falls. There are mainly two ways to bring down a building, 1. falling like a tree 2. Falling from crest to foot B.1 falli ng like a T ree In this method the blasting crew to collapses the building over on one side, into a parking lot or other open area with the help of blast . This sort of blast is the easiest to execute, and it is generally the safest way to perform demolition which is something like felling a tree. For example to topple the building to the north, the blasters detonate explosives on the south side of the building first , in the same way you would chop into a tree from the south side if you wanted it 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. B.2 falling from crest to foot Many times, a building is surrounded by numbers of structures that must be pre served. In this case, the blasters are used for true implosion, demolishing the building so that it collapses straight down into its own foot (that means the total area of building is removed into the base of the building). This requires great skill that o nly some handful of demolition companies in the world attempt it. V. C ONCLUSION Any t ype of building to be demolished, its method depends upon various factors such as site condition, type of structures, age of building, height of building and economy and mo st important its location with presence of its surrounding with its structural stability. Controlled demolition of building is necessary to ensure safety of both the workers and the surroundings so as to cause least amount of injuries and accidents . Explos ive demolition is the most preferred method for safely and efficiently demolishing the larger structures which requires a very high precision . International Journal of Emerging Technology and Advanc ed Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 3 , Issue 4 , April 2013 ) 401 Almost all major building implosio ns in the world are handled by 28 well - established companies, with lots of adv ancement coming day by day . REFERENCES [1] Code of practice for demolition of buildings by Building Departments of Hong Kong in 2004. [2] Planning committee of India, New Delhi . [3] Tom Harris, An article on How Building Implo sions work. [4] www.freelandconstruction.com/page75/page15/page64/index.html [5] www.n - somerset.gov.uk › Environment › Building Control [6] www.ispesl.it/risk_profiles/_building_demolition/index.pdf