Sufficient firefighting equipment should be located near any flammable or combustible liquid storage area. Only approved containers and portable tanks should be used for the storage and handling of flammable and combustible liquids. Heating devices should be situated so that they are not likely to overturn and shall be installed in accordance with their listing, including clearance to combustible material or equipment.
Temporary heating equipment, when utilized, should be maintained by competent personnel. Smoking should be prohibited at or in the vicinity of hazardous operations or materials. Where smoking is permitted, safe receptacles shall be provided for smoking materials. Roadways between and around combustible storage piles should be at least 15 feet wide and maintained free from accumulation of rubbish, equipment, or other materials. When storing debris or combustible material inside a structure, such storage shall not obstruct or adversely affect the means of exit.
A suitable location at the job site should be designated and provided with plans, emergency information, and equipment, as needed.
Access for heavy fire-fighting equipment should be provided on the immediate job site at the start of the job and maintained until the job is completed. Free access from the street to fire hydrants and to outside connections for standpipes, sprinklers, or other fire extinguishing equipment, whether permanent or temporary, should be provided and maintained at all times, as follows: Pedestrian walkways should not be so constructed as to impede access to hydrants.
No material or construction should interfere with access to hydrants, Siamese connections, or fire-extinguishing equipment. A temporary or permanent water supply of volume, duration, and pressure sufficient to operate the fire-fighting equipment properly should be made available.
Standpipes with outlets should be provided on large multi story buildings to provide for fire protection on upper levels. If the water pressure is insufficient, a pump should also be provided. An ample number of fully charged portable fire extinguishers should be provided throughout the operation.
All motor-driven mobile equipment should be equipped with an approved fire extinguisher. An alarm system, e. The alarm code and reporting instructions shall be conspicuously posted and the alarm system should be serviceable at the job site during the demolition.
Fire cutoffs shall be retained in the buildings undergoing alterations or demolition until operations necessitate their removal. Special Structures Demolition A. When preparing to demolish any chimney, stack, silo, or cooling tower, the first step must be a careful, detailed inspection of the structure by an experienced person.
Particular attention should be paid to the condition of the chimney or stack. Workers should be on the lookout for any structural defects such as weak or acid-laden mortar joints, and any cracks or openings. The interior brickwork in some sections of industrial chimney shafts can be extremely weak. If stack has been banded with steel straps, these bands shall be removed only as the work progresses from the top down.
Sectioning of the chimney by water, etc. Safe Work Practice When hand demolition is required, it should be carried out from a working platform. Experienced personnel must install a self-supporting tubular scaffold, suspended platform, or knee-braced scaffolding around the chimney. Particular attention should be paid to the design, support, and tie-in braces of the scaffold. A competent person should be present at all times during the erection of the scaffold. It is essential that there be adequate working clearance between the chimney and the work platform.
Access to the top of the scaffold should be provided by means of portable walkways. The platforms should be decked solid and the area from the work platform to the wall should be bridged with a minimum of two-inch thick lumber.
A back rail 42 inches above the platform, with a midrail covered with canvas or mesh, should be installed around the perimeter of the platform to prevent injury to workers below.
Debris netting may be installed below the platform. Excess canvas or plywood attachments can form a wind-sail that could collapse the scaffold. When working on the work platform, all personnel should wear hard hats, long-sleeve shirts, eye and face protection, such as goggles and face shields, respirators, and safety belts, as required. Care should be taken to assign the proper number of workers to the task. Too many people on a small work platform can lead to accidents.
An alternative to the erection of a self-supporting tubular steel scaffold is to "climb" the structure with a creeping bracket scaffold. Careful inspection of the masonry and a decision as to the safety of this alternative must be made by a competent person. It is essential that the masonry of the chimney be in good enough condition to support the bracket scaffold.
The area around the chimney should be roped off or barricaded and secured with appropriate warning signs posted. No unauthorized entry should be permitted to this area. It is also good practice to keep a worker, i. Special attention should be paid to weather conditions when working on a chimney. No work should be done during inclement weather such as during lightning or high wind situations. The work site should be wetted down, as needed, to control dust. Debris Clearance. If debris is dropped inside the shaft, it can be removed through an opening in the chimney at grade level.
The opening at grade must be kept relatively small in order not to weaken the structure. If a larger opening is desired, a professional engineer should be consulted. When removing debris by hand, an overhead canopy of adequate strength should be provided.
If machines are used for removal of debris, proper overhead protection for the operator should be used. Excessive debris should not be allowed to accumulate inside or outside the shaft of the chimney as the excess weight of the debris can impose pressure on the wall of the structure and might cause the shaft to collapse.
The foreman should determine when debris is to be removed, halt all demolition during debris removal, and make sure the area is clear of cleanup workers before continuing demolition. Demolition by Deliberate Collapse Another method of demolishing a chimney or stack is by deliberate collapse. Deliberate collapse requires extensive planning and experienced personnel, and should be used only when conditions are favorable. Considerable vibration may be set up when the chimney falls, so there should be no sewers or underground services on the line of the fall.
Lookouts must be posted on the site and warning signals must be arranged. The public and other workers at the job site must be kept well back from the fall area. The use of explosives is one way of setting off deliberate collapse. This type of demolition should be undertaken only by qualified persons. The entire work area shall be cleared of nonessential personnel before any explosives are placed.
Though the use of explosives is a convenient method of bringing down a chimney or stack, there is a considerable amount of vibration produced, and caution should be taken if there is any likelihood of damage. Demolition of Prestressed Concrete Structures The different forms of construction used in a number of more or less conventional structures built during the last few decades will give rise to a variety of problems when the time comes for them to be demolished.
Prestressed concrete structures fall in this general category. The most important aspect of demolishing a prestressed concrete structure takes place during the engineering survey. During the survey, a qualified person should determine if the structure to be demolished contains any prestressed members. It is the responsibility of the demolition contractor to inform all workers on the demolition job site of the presence of prestressed concrete members within the structure.
They should also instruct them in the safe work practice which must be followed to safely perform the demolition. Workers should be informed of the hazards of deviating from the prescribed procedures and the importance of following their supervisor's instruction.
Figure V Categories of Prestressed Construction There are four main categories of prestressed members. The category or categories should be determined before attempting demolition, bearing in mind that any prestressed structure may contain elements of more than one category. Category 1 Members are prestressed before the application of the superimposed loads, and all cables or tendons are fully bonded in the concrete or grouted within ducts.
Category 2 Like Category 1, but the tendons are left ungrouted. This type of construction can sometimes be recognized from the access points that may have been provided for inspection of the cables and anchors. More recently, unbonded tendons have been used in the construction of beams, slabs, and other members; these tendons are protected by grease and surrounded by plastic sheathing, instead of the usual metal duct.
The blasting exploder is the switch used to conduct electricity through detonators. These would be set up at a shed, metres away from the flats. Explosion on various floors would be carried out within a gap of milliseconds. Authorities have planned to carry out powerful explosions in the first phase and less powerful explosions in the second phase.
For example, the first explosion would be carried out only on the ground floor of the Holyfaith H20 flat. After 17 milliseconds, the next explosion would be carried out on the first floor. After 25 milliseconds, the next explosion would be carried out on the fifth floor and eighth floor. The explosions on the 11th and 14th floors would be carried out after milliseconds.
All the explosions would be carried out within milliseconds. The whole building would be razed to the ground within 45 seconds. There are apprehensions whether the rubble from the demolition of the Alfa Serene, Nettoor, would fall into the backwaters near Kundanoor bridge.
The pollution control board has set up special equipment to assess the contamination. Authorities have planned to make the Alfa Serene collapse at an angle of 45 degrees. This apartment complex has two towers. The debris from the second tower is more likely to fall into the backwaters.
Also, there are more houses adjacent to the second tower. The controlled explosion has been envisaged in a way to prevent the debris from falling on the houses. The attempt is to make the debris fall into the space between the twin towers.
However, most of the debris from the second tower would be made to fall towards the side of the backwaters. Authorities permitted for this after it was said that the debris falling in the waterbody can be removed later. However, authorities have not given a clear picture of how much debris would fall into the backwaters.
Efforts would be made to reduce the amount of debris that would fall into the backwaters. Demolition expert A B Sarwate had earlier said that two to three per cent of the rubble would fall into the backwaters during the time of the explosion.
There is no other option to prevent the debris from falling on the houses. Joe Brinkman, CEO of Edifice Engineering, the South African company that will carry out the demolition of Holyfaith H20 ensured that safety measures will be taken before the building is demolished.
Small amounts of concrete will fall and this cannot be completely avoided. Concrete is a material that dissolves into the ground, it can be scooped up from the backwaters if need be.
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