DEMOLITION

Süleyman Hilmi GÜL

DEFINITION

WHAT IS DEMOLITION ???????

Demolition is the DISMANTLING, RAZING, DESTROYING or WRECKING any building or structure or any part of building by PRE-PLANNED and CONTROLLED methods.

AND WIKI SAYS

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.

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.

Code of practice for DemolitionPlan

When preparing plans for demolitionworks, reference should be made to therelevant regulations in the BuildingsOrdinance and the Code of Practice forDemolition of Buildings issued by theBuildings Department (BD)

Scope of the CoP of Demolition

Outline good practices for PLANNING andIMPLEMENATION of demolition of variousbuilding works aiming at minimizing the risk of :– damage to people and properties of the PUBLIC;– endanger the health and safety of SITE PERSONEL;– damage to the neighborhood ENVIRONMENT.

PLANNING

Building appraisal by means of– Building Survey– Structural Survey– Demolition Plan & Stability Report includingCalculation– Utilities– Hazardous materials

DEMOLITION SUB-PLAN

Demolition Plan• location plan• layout plan• structural plan• procedure plan• plant routing and structural alteration• precautionary measures plan• shoring plan (outside)• shoring plan (inside)• debris disposal plan• Special safety considerations• Traffic• Post-demolition arrangement

STRUCTURAL SURVEY

A. Record DrawingsB. Survey ItemsC. Special StructuresD. Investigation and Testing

Record Drawings1.Studying the record layout, structural framing plans and structural details.

2.Checking if any unusual detailing that may cause abnormal structural behaviour during demolition.

Survey items• The structural materials used;• The original structural system employed;• The method of construction;• Condition of structural elements;• The structural conditions of adjoiningstructures;• The presence of continuous structures thatmay be truncated by the demolition

Special Structures• The correctness of structural informationavailable;• Any unconventional structural elements;• The possibilities of structural modification to enable efficient demolition traffic during demolition;• Any limitation on shoring and othertemporary supports.

Investigation & Testing

If no structural details are available, thestructural survey shall include:1. Site measurement;2. Field testing;3. Expose some key structural elements

Demolition Plans• The construction and condition of the building to be demolished, including sections showing slopes and ground supported by it, and all affected buildings, structures, streets, land and services• The existing nature of the site and surrounds (including an accurate survey plan with ground level contours and sections showing slopes and ground supported by the building to be demolished) and all necessary removal of ground

Demolition Plans (cont.)• The sequence, equipment and procedures for thedemolition works• The support to be provided to the building to bedemolished and any slopes and ground supported by itand all affected buildings, structures, streets, land andservices at each stage of the demolition works• All precautionary measures for the protection of thepublic including dust screens, catch fans, hoardings andcovered walkways• The support to be provided to all affected buildings,structures, streets, land and services at each stage ofthe demolition works

Methods of Demolition• Top-down manual • Top-down machines • Mechanical by hydraulic crusher withlong boom arm• Wrecking ball• Implosion• Others: non-explosive demolitionagent; saw-cutting; cutting and lifting;mechanical demolition; thermallance and water jet

Special Structures• Precast concrete structures• Prestressed concrete structures• Statically determinate structures• Composite structures and steel structures• Cladding walls• Hanging structures• Oil storage facilities• Marine structures• Underground structures• Structures supporting ground or sitting on slopes

Comparing Top-down manual and Top-down

machines methods• Manual: by jack (or pneumatic) hammers andoxy-acetylene torch• Machines: by percussive breaker, hydrauliccrusher and excavator arm• Similar Sequence: cantilevered slabs andprojected elements – roof – cantilever beams –secondary beams – main beams – nonloadbearing walls – columns and load bearingwalls.• Machines support and lifting: temporary rampconstruction

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