Incident Involving Collapse of Timber Formwork During Concreting Work

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There was an incident on 21 July 2010 at about 2.30 pm, within the Federal Territory Kuala Lumpur involving a construction project for the demolition and re-construction of existing multi-storey bangalow building.

The incident happened when the concreting work was in progress on the topmost level of the formwork for the slab.The collapse caused the whole dynamic loads to impact on the lower slab structure,formwork and timber supports that had been erected which then eventually weakened and failed.There were 9 workers working at that time.3 workers sustained injuries.

The investigation found that the formwork supporting members-battens,diagonal braces,reshores were not of sufficent strength to adequately support the imposed loads when the concreting work was in progress.The specifications and quality of the timbers used were found to inferior and sub-standard.There were many distinctive defects found on the timber supports used-cracks,splits,knots.Other defects were also found-plywood used was found to have debonded;starter bars were not installed complying to good construction practice; and fragments of the conrete were found to be porous.

The timber formwork supports which were defective contribute to the failure of the section of the permanent building structure which was under concreting.

It is strongly advised that the following safe work practices are followed for any design, construction, erection and inspection of timber formwork during concreting work:

1. Hazard identification, risk assessment and control (HIRARC) has to be carried out for any construction activity to ensure and provide a safe system of work. This is consistent with Section 15, Occupational Safety and Health Act 1994 which provide that it is the duty of the employer to provide safe system of work to ensure the health and safety of their workers and other persons other their own workers who might be affected by the activities that are being carried out.
2. Formwork and reshores shall be certified structurally safe by a Professional Engineer and shall be properly braced or tied together so as to maintain position and shape.
3. Upon the erection of the formwork, the designated person appointed by the main contractor shall make a thorough inspection to ensure that the formwork is safe.Similarly,the designated person shall regularly inspect the formwork,shores,braces and other supports during the placing of the concrete.Reshores shall be inspected together.Any unsafe condition discovered during the inspections shall be remedied immediately.Reference can be made to the Part III,Factories and Machinery(Building Operations and Work Of Engineering Construction)(Safety) Regulations 1970.
4. Timbers used for the formwork structure and supports should comply with the Malaysian Forest Trade Service Leaflet No. 38 specifications.

 

References:

1. Part III, Factories and Machinery (Building Operations and Work Of Engineering Construction) (Safety) Regulations 1970.
2. Guidelines on Public Safety At Construction Sites

 

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