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4.0 DEMOLITION WORKS 4.1 Understand on Demolition Works

Demolition is the tearing-down of buildings and other structures. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use.

For small buildings, such as houses, that are only two or three stories high, demolition is a rather simple process. The building is pulled down either manually or mechanically using large hydraulic equipment: elevated work platforms, cranes, excavators or bulldozers.

i. What Is Demolition? The Occupational Safety and Health Regulations 1996 define demolition and include regulations which relate specifically to demolition. These are regulations 3.114 to 3.128 in Subdivision 7, Division 9 of Part 3 of the regulations.

“In the Regulations "demolition" means the complete or partial demolition of a building or structure by pre-planned and controlled methods or procedures”.

“To demolish or dismantle a structure or part of a structure that is load-bearing or otherwise related to the physical integrity of the structure, but does not include the dismantling of formwork, false work, scaffolding or other structures designed or used to provide support, access or containment during construction work, or the removal of power, light or telecommunication poles” - Code of Practice (2009) developed by Safe Work Western Australia

“Demolition means dismantling, razing, destroying or wrecking any building or structure or any part thereof by pre-planned and controlled methods” – Malaysian Standard: Malaysia Code of Practice drafted (2009) developed by the Technical Committee for Construction Practices under the supervision of Construction Industry Development Board, Malaysia.

Not all work commonly understood to be demolition work is covered by regulations 3.114

to 3.128. These regulations do not apply to the demolition of a building or structure by a person in the metal fabrication or engineering industry in the course of maintaining, refurbishing, upgrading, modifying or decommissioning plant.

The exemption applies only to these particular regulations. Demolition work in mines is covered by the Mines Safety and Inspection Act and regulations made under that Act.

Larger buildings may require the use of a wrecking ball, a heavy weight on a cable that is

swung by a crane into the side of the buildings. Wrecking balls are especially effective against masonry, but are less easily controlled and often less efficient than other methods. Newer methods may use rotational hydraulic shears and silenced rock-breakers attached to excavators to cut or break through wood, steel, and concrete. The use of shears is especially common when flame cutting would be dangerous.

ii. Types And Ways of Demolition

In many circumstances, buildings and structures should be demolished in the reverse order to their erection; although where partial demolition is involved a more careful evaluation of the nature of the effects of the demolition is necessary. Normally, the demolition contractor is able to adopt a method of work which gradually reduces the height of the building or arranges the deliberate controlled collapse of the building or structure so that work can be completed at ground level.

The choice of demolition technique will depend on the nature of the building or structure

and its environment. Risks to the public, operatives involved in the demolition process and adjacent structures and buildings should be considered. Demolition techniques may be categorized as:-

a. Piecemeal demolition, using hand-held tools or machines, to reduce the height of the building or structure gradually

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b. Deliberate controlled collapse, demolition to be completed at ground level

General guidelines are also given for the design of temporary works and checking of temporary structures. The code covers common methods typically used in the demolition of buildings in Malaysia, but exhaustive guidelines for all methods are not given. The code does not intend to discourage any other demolition methods, which may be used subject to approval. The content of the unit includes the following topics:

a. Demolition Processes b. Demolition Methods c. Machinery used in demolition d. Demolition Tariffs And Reasons For Demolition

4.1.1 The Objectives Demolition Works With the increased number of fatal accidents caused by demolition of high rise buildings,

safety in demolition works becomes a great concern to both the government and the public. The reasons leading to such horrible accidents are many, of which the lack of planning and supervision are the major ones.

Following the issuance of various practice notes to: i. Authorized persons ii. Registered structural engineers iii. Registered contractors iv. Regarding the safety measures for demolition works for the protection of the Public v. The building department has recently prepared a draft of the Code of Practice for

Demolition of Building.

It is intended to be followed by specialist demolition contractors for the demolition of various building works in Malaysia, aiming at minimizing the risks of injury to persons and damage to properties, the risks of endangering the health and safety of site personnel and damage to the environment in the vicinity.

The Code sets out the guidelines for demolition of the buildings from roof level to ground

level and the demolition of basement, underground tanks, as well as certain common civil engineering structures, but not major civil engineering works such as underpinning, excavation, highway bridges, dams and nuclear reactors.

4.1.2 The Reasons of Demolition Works Demolition of buildings usually refers to the act of pulling down a building or part of a

building. There can be various reasons for demolition, it is: i. Commercials ii. Aesthetic iii. Human health iv. Human safety v. Build new buildings vi. Renovation vii. Structure problems viii. Environment (near slopes) ix. Population density x. Adjacent buildings xi. Traffic

4.2 Method of Demolition

The sequence in which a building or other structure is demolished can be critical for the health and safety of workers and the general public. The demolition sequence will depend on things like the type of construction, location, and demolition method(s) selected. Buildings and structures should generally be demolished in reverse order to their construction, that is, by ‘sequential demolition’. In particular:

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i. Sequential demolition should be carried out in reasonably even stages, commencing from the roof or top of the building or structure being demolished.

ii. Multi-storey buildings or structures should be demolished storey by storey iii. masonry and brickwork should be taken down in reasonably even courses.

There is a range of demolition methods that may be used, either separately or in

combination. Control measures should be selected on the basis of the demolition method(s) used. However, no matter what method is used, the building or structure to be demolished and all its components should be maintained in a safe and stable condition so as to prevent the unexpected collapse of part or all the structure. Temporary braces, propping, shoring, or guys may need to be added for stability.

4.2.1 Manual Demolition

The demolition works by manually should be: a. Manual demolition includes any technique where hand tools such as jackhammers,

sledgehammers and picks are used. b. Manual demolition has many of the hazards that are present in other major demolition

activities including unexpected collapse, falls, falling objects, manual handling and exposure to noise, dust and hazardous chemicals.

c. To manage the risk of unplanned collapses, the condition of roofs, walls and floors of the building should be assessed by a competent person before commencing demolition work.

d. Where concrete members are being demolished manually, the reinforcement shall not be cut while breaking of the concrete is in progress.

e. Where pre and post-tension demolition work is undertaken competent person advice should be sought as to demolition sequence. More information on the demolition of pre and post- tensioned concrete is at Section 6.1 of this Code.

f. Areas where debris will fall should be barricaded off and signs erected to prevent persons from entering before demolition starts.

i. Manual Demolition of Roofs

Where it is not reasonably practicable to demolish a roof using mechanical means or to remove the roofing from work platforms below the roof, then careful consideration should be given to the most suitable method of protection for workers engaged in the removal of the roofing. For example, roof trusses should be removed using safe temporary work platforms. It is important to ensure that the removal of trusses does not cause wall instability.

Controlling the risk of falls of persons or objects is an important consideration for roof

work. Prior to commencing roof demolition or dismantling, you should consider: a. Fall hazards b. Structural stability c. Condition and strength of the roofing material and the identification of fragile roofing d. Identification of fragile panels or skylights in solid roofs e. Crane access f. Safe worker access and egress g. Fall protection requirements including issues such as perimeter protection, the

availability and strength of anchor points for static lines, inertia reels and lanyards and the suitability of roof structure for the use of safety nets

h. Means of rescuing persons from safety nets or safety harnesses i. The condition of any roof mesh or safety mesh j. Methods of raising and lowering equipment and materials k. Assessment of manual handling problems l. Electrical safety including the location of nearby power linen m. Worker competency and training needs

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ii. Fragile Roofs Before working on the roof, the roof should be inspected to identify that it is

structurally adequate to work on and whether there is any brittle material or if the roof has a fragile aspect to it (for example, a skylight or worn section).

Brittle or fragile roofing material can include roofing made of asbestos cement,

cellulose cement, glass panels, fiberglass, acrylic or other similar synthetic molded or fabricated material used to sheath a roof or contained in a roof.

If asbestos cement roofing is involved, the work must be undertaken in accordance

with the asbestos related requirements of the WHS Regulations. Further information can be found in the Code of Practice: How to Safely Remove Asbestos.

Where it is necessary for work to be carried out or adjacent to any part of a fragile

roof, you should: a. Inspect the underside of the roof to determine the extent of the fragile roof material,

the existence of any safety mesh and its fixings, and the structural soundness of the roof material

b. Complete the work from a temporary work platform c. provide temporary walkways as a means of access to and egress from any work area

on the roof where permanent walkways are not provided d. secure and fix cleats to walkways on high pitch roofs (for example, where the slope

of the roof exceeds 1:6) e. provide temporary roof ladders for steep roofs (for example, in excess of 35 degrees) f. provide other fall protection as necessary (for example, work positioning or fall arrest

system).

iii. Roof access The person conducting a business or undertaking where persons are employed to

work on roofs has a responsibility to ensure that the access from the ground to the actual work area is safe and without risk to health. Access arrangements may include personnel hoists, scaffolding, temporary work platforms and ladders.

iv. Purlin Trolleys

Purlin trolleys are plant designed to travel on top of purlins (horizontal beams running along the length of a roof) and can be used to support material and roof workers. They are sometimes used during the removal of roof coverings.

Purlin trolleys should be provided with a

holding brake and a device to prevent their accidental dislodgment from the supporting purlins. Where it is intended that the roof workers be supported by the trolley, the trolley should be provided with suitable safety harness anchorage points. Before a purlin trolley is placed on a roof structure: a. A competent person (e.g. a structural

engineer) should have considered whether the roof structure is suitable for the particular purlin trolley and its operational loads

b. The purlin trolley should be designed and constructed to withstand the loads placed on it and for the purpose of the safe movement of materials and/or persons across the roof surface.

Figure 4.1: Demolition to access

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Figure 4.3: Demolition of members and floor

Figure 4.2: Demolition of wall

v. Manual Demolition of Walls Glass should be removed from the windows, doors or

openings before the commencement of the demolition work.

Walls and gables should be demolished course by course. All work should be performed from safe working platforms. Workers should not work from the top of a wall or partition being demolished. A wall or partition should not be permitted to stand, unless it is effectively supported against collapse, including being supported against lateral loads from wind and other forces.

If the demolition work involves the demolishing course by

course of any walls, columns, piers or other vertical structural members, the demolition contractor should check that: a. Risks to persons and property from falling collapsing and

rebounding material are laminated or minimized b. The remaining portion of the building or structure, if any,

can withstand any loads, impacts and vibration caused by felling or other environmental factors such as wind.

vi. Manual Demolition of Floors and Members All floors and other surfaces used to support workers, plant, equipment or materials

should be assessed as capable of supporting the load. Suspended floors and their supporting members should not be loaded by workers, plant, falling or accumulated debris/materials to the extent that there is excessive deflection, permanent deformation or danger of collapse. If water is used, the increased weight of the watered debris should be taken into account.

Openings in floors, through which a

person may fall, shall be properly guarded or boarded over and the boarding secured against accidental removal. Any covers or boarding of openings in floors should be of sufficient strength to withstand any expected loads that may be imposed on the floor, for example elevating work platforms, people and material.

Drop zones should be isolated

and/or guarded to protect workers and the public from falling objects. When jack hammering concrete floors, sufficient reinforcing steel should be left in position as protection against collapse or to prevent persons falling through the floor.

vii. Manual Demolition of Frameworks

Before any framework is demolished or removed, all reasonably practicable precautions should be taken to prevent the rest of the building collapsing as a result.

A competent person (for example, a structural engineer) should undertake an assessment to determine the necessary supports required when cutting members. Members should not be cut unless they are supported safely and effectively. Measures should be taken to prevent sudden spring, twist, collapse or other movement of the framework when it is cut, released or removed.

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Any framework which is not demolished should be strong enough to remain safely in position, or should be guyed or otherwise supported to ensure that it will be stable in any adverse weather conditions. Framework members should be lowered in a controlled manner. Tag lines should be used on loads where necessary to control the load.

4.2.2 Mechanical Demolition Work

Mechanical demolition involves the use of powered mobile plant, such as excavators, cranes, loaders and bulldozers. There may be a mix of hand and mechanical demolition methods applied.

All powered mobile plant used for demolition work must be fitted with a suitable combination of operator protective devices. Operator protective structures should be designed to the appropriate standard that eliminates or minimises the risk, so far as is reasonably practicable, of operator injury due to: i. Roll over and consequent cabin impact damage ii. Objects falling on or over the cabin iii. Objects penetrating the cabin iv. Hazardous noise

Demolition should be planned to be systematic and sequential. That is, a structure should

be demolished in the reverse order to which it was constructed. Mechanical demolition generally involves the use of large machinery with attachment to dismantle the building from outside. The common mechanical methods include the use of a pusher arm, wire rope and clam shell. These methods shall only be applied to isolated buildings on relatively flat ground.

The concerns and good practices of the mechanical demolition generally included the following:

a. The machine shall be operated on smooth and firm ground. It shall also have adequate counter-weight to prevent overturning during the operation;

b. The equipment and accessories such as attachments and rope shall be inspected frequently and shall be repaired or replaced whenever necessary;

c. The impact of the collapsed structural sections on the floor or ground shall be checked to prevent the potential overloading of the suspended floor, vibration and disturbance to adjacent properties and damage to underground utilities;

d. The site shall have full time security to prevent unauthorized personnel entering the site. No person shall stay within the working area of the machine and the building while the machine is operating;

e. Sufficient water spray or other anti-dust precautions shall be provided to minimise air pollution by dust;

f. The cab of the machine shall be equipped with impact proofed glass and its construction shall be robust enough to protect the operator from flying debris;

g. A spot person shall be on site full time to provide guidance and assistance to the operator in the demolition process.

In addition to the above, specific criteria for each mechanical method are discussed in the

following sections: a. Deliberate Collapse Mechanical b. Wire Rope Pulling c. Saw cutting d. Cutting and lifting e. Clam Shell f. Non explosive demolition agent g. Thermal lance h. Water Jet i. Crane and the demolition ball j. Pneumatic impact tool k. Pusher Mechanical Arm l. Explosive

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Crane and the Demolition Ball Balling machines generally comprise a drag-line type crawler chassis fitted with a lattice

crane jib. The demolition ball, with a steel anti-spin device, is suspended from the lifting rope and swung by the drag rope.

Balling should only be carried out by skilled operatives under the control of experienced supervisors using well maintained machines adequate for the proposed duty and standing on a firm, level base. The manufacturer should be consulted before a machine is used for balling to establish any restrictions on the type or length of jib or the weight of the ball. Balling operations subject cranes to dynamic stresses and wear, and the ball chosen should have the minimum weight necessary for effective use.

In many cases, demolition balls of quite light weight will be adequate. Floors should be demolished by dropping the ball on the highest remaining floor and allowing the debris to fall inside the building. The debris should be removed regularly to prevent excessive weight accumulating on the lower floors. Walls or columns can be demolished either by swinging the ball in line with the stationary jib, using the drag rope, or by slewing the jib. The ball should not swing by derricking the jib.

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-maintained equipment. Figure 4.16 illustrates the operation of Wrecking Ball.

The recommended criteria for the use of wrecking ball are presented in the following: i. Except for special application, the balling of each section of the structure shall proceed

from top to bottom. Care shall be taken to maintain the stability of the structure

ii. Recommended techniques for the wrecking ball operations include: a. Vertical Drop - free falling of the wrecking ball onto the structure; b. 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. The ball shall strike at the top of the member so as to avoid the member from falling outside the building.

Slewing the jib is not recommended. The motion of the ball by slewing the jib is difficult to control. It demands expert knowledge of the machine and structure as well as operating skills to safely perform the task. Slewing can potentially induce a tremendous amount of stress on the jib, as such; its use shall be avoided

iii. The jib or boom shall be operated with no less than 3 m above the portion of the structure being demolished

iv. Clear space for operation between the crane and the structure being demolished shall be 50 % of the height of structure, the clear distance between the site boundary and the building to be demolished shall not be less than 50 % of the building height plus an additional 6 m for the crane to manoeuvre, this criteria shall apply to all sides of the building to be demolished by wrecking ball

v. The demolition ball shall be connected with swivel type anti-spin device to prevent

twisting and tangling of the wire during operation vi. The wire and boom of the machine used for balling shall have a rated capacity, at the

working radius, of at least 5 times the weight of the ball vii. The strength of the wire shall be at least twice the tensile strength of the nominal steel

reinforcement of the floor slab and beams. The high strength wire allows the pullout of the wrecking ball from potential traps

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viii. To ensure that the crane is in good condition, the wire connecting to the ball, the boom

components and connecting pins shall be inspected twice daily ix. A sufficient length of the wire shall be provided to allow the ball to drop to the lowest

working level plus an addition of 10 % of the wire length and no less than 3 drums. x. For swing in-line method, there shall be sufficient length of the dragline wire to allow the

ball to fall in the event that the ball is entangled with the falling debris xi. The operation shall not be performed adjacent to overhead power lines xii. The site shall be entirely fenced off to forbid public access. A 24-hour security guard shall

be assigned to the site to enforce the access restriction; depending on the relative location between the fence and the building, and fence shall be designed to withstand accidental impact by the wrecking ball

xiii. During the use of the demolition ball, except for the crane operator and the spot person,

all other workers shall be kept away from the demolition ball’s working radius. No body shall stay inside the building

xiv. To minimise 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

xv. Since the safety and success of the project depend highly on the operator and site personnel, the operator must have proven experience and skill for operating the wrecking ball to the satisfaction of the approval authority

xvi. A spot person shall be on site during the operation to assist the operator and to ensure

site safety. The spot person shall have extensive knowledge and experience in the use of wrecking ball. The qualification and experience of the spot person shall be equivalent to those of the wrecking ball operator

Pneumatic Impact Tools

What are pneumatic impact tools? : A pneumatic tool or air tool is a tool driven by a gas, usually compressed air supplied by a gas compressor. Pneumatic tools can also be driven by compressed carbon dioxide (CO2) stored in small cylinders allowing for portability. Pneumatic tools are commonly cheaper and safer to run and maintain than their electric power tool

Figure 4.4: Crane and the demolition ball

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counterparts, as well as having a higher power-to-weight ratio, allowing a smaller, lighter tool to accomplish the same task.

Air tools were formerly unpopular in the market, but are becoming increasingly popular, and have always been ubiquitous in industrial and manufacturing settings. The example of pneumatic impact tools includes: i. Nail drivers ii. Demolition hammers iii. Chipping hammers iv. Riveting hammers v. Air impact wrench vi. Jackhammer vii. Pneumatic angle grinder viii. Pneumatic drill

They are driven by way of a pneumatic cylinder (tacker, nail driver) or by way of

oscillating linear motors (demolition hammers, chipping hammers, riveting hammers, needle descales).The samples tools function: i. Air drill for the same applications as you would an electric drill. ii. Air sander for sanding wood and metal or for removing rust from a vehicle before painting. iii. Air stapler to lay a carpet or upholster furniture with ease. iv. Concrete demolition tools that fall under this category include paving breakers and

chipping hammers. Its can use paving breakers to demolish concrete floors, patios, sidewalks, driveways, parking lots and other hard surfaces.

v. Chipping hammers allow to chisel away specific areas of concrete. vi. Impact wrench to tighten or remove bolts quickly, an air impact wrench can come in

handy. When choosing an air impact wrench, keep in mind the size of the bolts can will tighten and the amount of torque you will need.

vii. Nail guns to specifically designed for a number of purposes including framing, roofing, fencing, siding, flooring and finishing.

viii. Sandblaster to remove rust or old paint from boat hulls, swimming pools or masonry work using a rented air sandblaster.

Figure 4.5: A single phase demolition breaker

Figure 4.7: A gas breaker on a deconstruction site

Figure 4.6: A compressor for running a pneumatic jackhammer and air drill

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Pusher Mechanical arm The crusher attachment breaks the concrete and the reinforcement 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.

For environmental reason, it should be used wherever practicable because of its

quietness. Articulated, hydraulically-powered pusher-arm machines are normally mounted on a tracked or wheeled chassis, and have a toothed plate or hook for applying for applying a horizontal force to a wall. The machine should stand on a firm level base and apply force by a controlled movement of the pusher arm.

Figure 4.8: Long arm hydraulic machine with crusher

Figure 4.9: Long arm hydraulic machine with jackhammer

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Explosive If explosives are to be used for demolition, the planning and execution, include pre-

weakening, should be under the control of a person competent in these techniques. For large demolition, the competent person is likely to be an experienced explosive engineer; for smaller work, a shot-firer may be sufficient.

When the use of explosives is contemplated, it is usual to employ a technique that will

ensure the total demolition of the whole building by staging a controlled collapse. The explosive charges are set and fired in a sequence that will weaken the structure in such a way that the building collapses in upon itself. Although we tend to think of explosives as devices producing spectacular bomb-like explosions, the use of non-explosive "explosives" is now at an advanced stage. These non-explosive techniques are essentially expanding charges that achieve the same results as explosives but without the noise and initial devastating blast.

The term building implosion can be misleading to laymen: the technique is not a true implosion phenomenon. A true implosion usually involves a difference between internal (lower) and external (higher) pressure, or inward and outward forces, that are so large that the structure collapses inward into itself.

In contrast, building implosion techniques do not rely on the difference between internal

and external pressure to collapse a structure. Instead, the technique weakens or removes critical supports so that the building can no longer withstand the force of gravity and falls under its own weight.

Numerous small explosives, strategically placed within the structure, are used to catalyse

the collapse. Nitro-glycerine, dynamite, or other explosives are used to shatter reinforced concrete supports. Linear shaped charges are used to sever steel supports. These explosives are progressively detonated on supports throughout the structure. Then, explosives on the lower floors initiate the controlled collapse.

A simple structure like a chimney can be prepared for demolition in less than a day.

Larger or more complex structures can take up to six months of preparation to remove internal walls and wrap columns with fabric and fencing before firing the explosives.

As part of the demolition industry, the history of building implosion is tied to the

development of explosives technology. One of the earliest documented attempts at building implosion was the 1773 razing of Holy Trinity Cathedral in Waterford, Ireland with 150 pounds of gunpowder, a huge amount of explosives at the time. The use of low velocity explosive produced a deafening explosion that instantly reduced the building to rubble.

Figure 4.10: Building demolition with blasting

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The late 19th Century saw the erection of-and ultimately the need to demolish-the first skyscrapers, which had more complicated structures allowing greater heights. This led to other considerations in the explosive demolition of buildings, such as worker and spectator safety and limiting collateral damage. Benefiting from the availability of dynamite, a high-velocity explosive based on a stabilized form of nitro-glycerine, and borrowing from techniques used in rock-blasting, such as staggered detonation of several small charges, building demolition edged toward efficient building implosion.[citation needed]

Following World War II, European demolition experts faced with massive reconstruction

projects in dense urban areas gathered practical knowledge and experience for bringing down large structures without harming adjacent properties. This led to the emergence of a demolition industry that grew and matured during the latter half of the twentieth century. At the same time, the development of more efficient high-velocity explosives such as RDX and non-electrical firing systems combined to make this a period of time in which the building implosion technique was extensively used.

General concerns and good practices in controlled demolition by blasting are discussed in the

following: i. Pre-weakening of the structure shall be designed to ensure the structural stability before the

implosion;

ii. To minimise the dispersion of building debris into adjoining land after blasting, a trench or bund wall shall be installed outside the building to contain the debris, unless a basement exists;

iii. A good design will cause the structure to fall towards the centre of the building and/or within the protected area;

iv. A good design will provide adequate and sufficient time delay to allow only one or two floors of the building debris to fall on ground level at a time in order to limit the magnitude of the impact on the ground;

v. The design must also identify an exclusion zone to evacuate all residents or inhabitants during the blasting. The impacts of noise and dust generated during the blasting shall be considered. Radius of the typical exclusion zone shall not be less than 2.5 times the building height;

vi. If there are slopes and earth retaining walls or features, a geotechnical assessment shall be conducted to ensure that the blasting will not affect the stability of these features;

vii. The entire site shall be under 24-hour security from the installation of explosive until final blasting. The implosion expert shall have proven experience and track records in design and supervision of blasting similar building structures. The blasting expert shall have acquired the relevant training and practical experience in using the proposed explosives. The blasting expert shall obtain permission from the Police before carrying out blasting. All personnel must be evacuated from the site before and during blasting;

viii. The Registered Specialist Contractor (Demolition) must co-ordinate with the government and local community to determine the best procedures in notification, schedules for the events, traffic routing, design for the sequence of events, evacuating residents, clear out personnel from the building and assigning responsibilities during blasting. For the purpose of crowd control, blasting should be carried out in the early morning of a Sunday or public holiday;

ix. An emergency plan shall be prepared to handle emergency situations such as premature explosion, misfire or interruption due to bad weather including thunder and lightning;

x. After the explosion, the blasting expert must check to make sure that there is no unfired explosive left on site. The entire area must remain clear and under security control until the unfired explosives have been detonated or safely dealt with by the blasting expert;

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xi. As far as practicable, non-electrical initiation systems should be used to avoid the risk of pre-mature detonation by stray currents, external electro-magnetic waves or radio frequencies. The installation shall include a redundant system to ensure successful detonation. Nitro-glycerine based explosives are not permitted to be used

xii. The Registered Specialist Contractor (Demolition) must provide evidence of his capability to safely perform the demolition and shall illustrate to the approving authorities that the procedures are safe

xiii. The mode of collapse shall be demonstrated to ascertain that: a. No part of the building will fall beyond the protected area; b. The impact of the structural collapse will not cause significant vibration affecting

Any underground tunnels Any underground utilities Any adjoining properties

xiv. The structural safety of the building to be imploded shall be checked and certified to be sound

and safe at all stages prior to implosion.

4.3 Safety Procedures and Best Practices of Demolition Works

The choice of demolition method depends on the project conditions, site constraints, and sensitivity of the neighborhood and availability of equipment.

Top down methods are applicable for most sites, particularly for those situated in busy

urban areas. Other mechanical methods applied from the outside of the building may be suitable for projects that have sufficient clear spaces. For structural projections, such as balconies, canopies and verandas extending beyond the building lines, demolition by hand held tools or the cut and lift process may be a safe solution. Methods using wrecking ball and explosive should be adopted with extreme care when well-planned adequate precautionary measures are provided. The applications of demolition methods are summarized in figure 4.11.

The suggested procedures described in this Code of Practice are recommended good

practices for demolition of common structural elements only. Each site has its specific features and conditions. The method, including detail procedures, shall be designed to accommodate the specific project requirements. In general, demolition should be carried out in the reverse order of construction, as far as appropriate.

Figure 4.11: The application of demolition method

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4.3.1 License Required For All Demolition Works A license is required to carry out certain types of demolition work. It is an offence to do

any of the work described as class 1, class 2 or class 3 demolition work unless licensed to do the work.

i. Class 1 a. Work comprising the total demolition of a building or structure that is 10 metres or

more in height when measured from the lowest ground level of the building or structure to the highest part of the building or structure

b. Work comprising the partial demolition of a building or structure that is 10 metres or more in height when measured from the lowest ground level of the building or structure to the highest part of the building or structure affecting the structural integrity of the building or structure

c. Work comprising the total or partial demolition of a building or structure; and involving the use of load shifting equipment on a suspended floor

d. Work comprising the total or partial demolition of pre-tensioned or post-tensioned structural components of a building or structure

e. Work comprising the total or partial demolition of a building or structure containing precast

f. Work involving the removal of key structural members of a building or structure so that the whole or a part of the building or structure collapses

g. Work done to a building or structure involving explosives h. Work comprising the demolition or partial demolition of a building or structure that

involves the use of a tower crane or any crane with a safe working load greater than 100 tonnes

i. Work involving the removal of an area of brittle or fragile roofing material in excess of

200 m2

from a building or structure if any part of the area to be removed is 10 metres or more above the lowest ground level of the building or structure

ii. Class 2,

a. Work comprising the total or partial demolition of a building or structure that is less than 10 metres in height when measured from the lowest ground level of the building or structure to the highest part of the building or structure but does not include :

the total or partial demolition of a single storey dwelling work of a kind referred to in paragraphs (c), (d), (e), (f), (g), or (h) of the

definition of class 1;

iii. Class 3 a. Work comprising the removal of more than 200 m² of brittle or fragile roofing material

from a building or structure 4.3.2 Special Safety Considerations

i. 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.

Site safety and project understanding shall be promoted through an induction meeting

at the beginning of the project, where information related to the project such as the proposed method and procedures, potential danger during the operation, safety measures and project specifics can be disseminated to all on site personnel.

The safety concept can be maintained by regular safety meetings throughout the

project period. Site safety attitude may be cultivated by strict enforcement of the safety regulations by the site supervisor.

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Apart from instilling the importance of safe attitudes to workers and plant or equipment operators, they shall be trained by competent instructors on the following to observe safety precautions:

a. Working at Heights b. Working in Confined Spaces c. Working with Lifting Appliances and Lifting Gears d. Use of Personal Protective Equipment e. Hot Works f. Handling of Chemicals g. Health Hazards in Demolition Works h. Safe plant operating zones and safe plant manipulation zones.

ii. 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.

iii. Electrical Safety

A properly connected power source from a local electric utility supplier or a mobile electricity generator shall be utilized in demolition sites.

iv. Fire 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.

v. Occupational Health

The health of workers on site shall be properly protected particularly on the following areas:

a. Exposure to Dust b. Chemical Exposure c. Heat Stress and Ventilation d. Noise Exposure e. Medical and First Aid Facilities f. Sanitation g. Occupational Diseases h. Poisoning.

vi. Emergency Exit Requirements in Demolition Sites

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.

vii. Vibration

Demolition work will cause vibration to neighbouring buildings or structures to various extent, depending on the method of demolition. The most serious vibration is caused by implosion. The effect of vibration caused by implosion are categorised as follows:

a. Permanent ground distortion produced by blast-induced gas pressures b. Vibratory settlement of foundation materials

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c. Projectile impact (i.e. blast fly rock) d. Vibratory cracking from ground vibration or air blast.

These effects will have to be dealt with specifically in the method statement for implosion.

For other mechanical demolition methods, the vibration effect is usually less than some other construction processes, such as percussive piling and blasting. In some cases, the traffic vibrations caused by heavy duty tractors are more significant than that caused by mechanical demolition. In order to identify the actual cause and effect of vibration. As a general guideline, the peak particle velocities at any adjoining structure shall not exceed 15mm/sec for prolonged vibration caused by mechanical demolition.

4.3.3 Environmental Precautions

The general requirements to minimise environmental impacts from construction sites can also be applied to demolition processes. The following sections contain some of the procedures to be adopted:

i. Air Pollution

Concrete breaking, handling of debris and hauling process are main sources of dust from building demolition. Dust mitigation measures shall be adopted to minimise dust emissions. Burning of waste shall not be allowed.

ii. Noise

Noise pollution arising from the demolition works including, but not limited to, the use of specified powered mechanical equipment (SPME), powered mechanical equipment (PME), such as pneumatic breakers, excavators and generators, etc., scaffolding, erection of temporary works, loading and transportation of debris, etc. affects the workers, and the sensitive receivers in the vicinity of the demolition site. Silent type PME shall be used to reduce noise impact as much as practicable. Demolition activity shall not be performed within the restricted hours.

iii. Water

The discharge of wastewater from demolition sites requires an approval by Department Of Environment (DOE). Effluent shall be treated to the standards as stipulated by DOE Regulation before discharge.

iv. Hazardous Materials Materials such as liquefied petroleum gas (LPG) cylinders in domestic flats, toxic and

corrosive chemicals for industrial undertakings, and any other hazardous materials have to be identified and properly handled and removed prior to the commencement of the demolition of the building.

In the summaries, best of practices and environments effect in demolition works were: i. The stability and structural integrity of the structure at all stages of demolition, including

assembled portions, single components and completed sequentially erected braced bays. ii. The maximum permissible wind speed for partially demolishes structure. iii. The effect of the proposed demolition squeeze on stability. iv. The stability requirements for all components of the structure as it is sequentially

demolished according to adjoin building. v. The proximity of adjacent of loadings at all stages of demolition. vi. The provision of clear. vii. The proposed methods for handling heavy, bulky or awkward components. viii. The need for specific lifting arrangements to detailed on structural member drawings to

facilitate safe lifting. ix. The handling, lifting, storing, stacking and transportation of components, depending on

their size, shape and weight. x. The provision of safe access and safe working areas.

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4.4 Demolition Works Sign .

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4.5 References Books

Egan M David (1986). The Building Fire Safety Concept. University Technology Malaysia, Skudai.

Fullerton R. L. (1979). Building Construction in Warm Climates. Volume 1, 2, 3. Oxford

University Press, United Kingdom. Hall F. (2000). Building Services & Equipment. Pearson Limited, England. MS EN 81-1:2012. Malaysian Standard. Safety Rules for the Construction and Installation of

Lift- Part1: electric Lifts (first revision). Department of Standards Malaysia. Nor Rizman (2010). Risk Assessment for Demolition Works In Malaysia. Faculy of Civil

Engineering and Earth Resources, Universiti Malaysia Pahang. Undergraduate thesis.

Prashant A/L Tharmarajan (2007(. The Essential Aspects of Fire Safety Management In Hihg-

Rise Buildings. University Teknologi Malaysia. Degree of master science thesis. Riger W. Haines, Douglas C. Hittle (2006). Control System for Heating, Ventilating and Air

Conditioning. Springer-Verlag, New York. Stein, Benjamin, Reynolds, John S., Grondzik, Walter T., and Alison G. Kwok, (2006).

Mechanical and Electrical Equipment for Buildings. 10th ed. Hoboken, New Jersey: John Wiley and Sons, Inc., 2006.

Tan, C. W. and Hiew, B.K., (2004), “Effective Management of Fire Safety in a High-Rise

Building”, Buletin Ingenieur vol. 204, 12-19. Journals N.H. Salleh and A.G. Ahmad. (2009). Fire Safety Management In Heritage Buildings: The

Current Scenario In Malaysia. CIPA Symposium Kyoto Japan. UIAM and USM. Code of Practices Approved Code Of Practice For Demolition: Health And Safety In Employment Act 1992.

Issued And Approved By The Minister Of Labour September 1994. Code of Practice for Lift Works and Escalator Works. (2002 ed). Code Of Practice For Demolition Of Buildings 2004. Published by the Building Department.

Printed by Taiwan Government Logistics Department. Code Of Practice For Demolition Of Buildings (2009). Malaysia Standard Supersede Ms 282

Part 1: 1975. Technical Committee For Construction Practices Under The Supervision Of Construction Industry Development Board, Malaysia.

Demolition Work Code Of Practice (July 2012). Australian Government. Work Health and Safety (Demolition Work Code of Practice) Approval 2012. Australian

Capital Territory. By Dr Chris Bourke, Minister for Industrial Relations. Others Publishing

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Coby Frampton. Benchmarking World-class maintenance. CMC Charles Brooks Associates,

Inc. Electrical Installation and Systems (2006). Training Package UEE06. Industry Skills Council,

Australia. Fire Safety Manual (2002). Florida Atlantic University USA. Garis panduan Pendawaian Elektrik di bangunan Kediaman (2008). Suruhanjaya Tenaga

Malaysia. Jabatan Keselamatan Elektrik. Laws of Malaysia. Act 341: Fire Services Act 1988. Publish by The Commissioner Of Law

Revision, Malaysia Under The Authority Of The Revision Of Laws Act 1968 In Collaboration With Percetakan Nasional Malaysia Bhd 2006.

Operations & Maintenance Best Practices: A Guide to Achieving Operational Efficiency.

(August 2010). Release 3.0. Principles of Home Inspection: Air Conditioning and Heat Pumps. (2010). Educational Course

Note. Routine Maintenance Modules. Part II. Uniform Building By Law 1984. (1996). MDC Legal Advisers: MDC Publishers Printers Guidelines For Applicants For A Demolition Licence Issued Under The Occupational Safety

And Health Regulations 1996. Occupational Safety And Health Act 198. The Government of Commerce, Western Autralia.

Websites http://en.wikipedia.org/wiki/Electricity http://science.howstuffworks.com/electricity.htm http://en.wikipedia.org/wiki/Electricity_generation https://en.wikipedia.org/wiki/Fire_safety http://www.usfa.fema.gov/citizens/home_fire_prev/ https://en.wikipedia.org/wiki/Maintenance,_repair,_and_operations http://academia.edu/406774/Demolition_Work_in_Malaysia_The_Safety_Provisions http://www.mbam.org.my/mbam/doc/news/010-05Oct09-COP%20Demolition%20Works-corrected%20on%20%2030th%20sept%202009-1.doc http://en.wikipedia.org/wiki/Demolition http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/700/Demolition%20Work.pdf https://en.wikipedia.org/wiki/Air_conditioning http://www.nasa.gov/topics/earth/features/heat-island-sprawl.html

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http://www.projectnoah.org/education http://unfccc.int/files/methods_and_science/other_methodological_issues/interactions_with_ozone_layer/application/pdf/subgene.pdf http://www.cibse.org/Docs/barney2.doc http://en.wikibooks.org/wiki/Building_Services/Vertical_Transportation