The Application of formwork for High–rise & Complex Building Structures

Formwork system is the key factor determining the success of a construction project in terms of speed a formwork system if not appropriate designed to fit the actual site condition will have low efficiency and affect the speed of work
(e.g. wrong selection, inefficient fixing method, difficult location of work, more labour intensive etc.)

In terms of quality, the formwork system is key to the success of a construction project

There are several ways in which formwork can affect concrete quality:

  1. a) the accurate shape of the formwork panel
  2. b) dimensional accuracy of the formwork
  3. c) the verticality, leveling or alignment of the formwork
  4. d) the tightness of joining of the panels
  5. e) whether the panel surfaces is in good condition

In order for a construction project to succeed in terms of cost, the formwork system is important; cost of formwork includes material (plywood and hardwood walking), cost of cutting, material wastage, labour to assemble and erection, striking and transportation of formwork panels, replacement of reused panel etc.

 

formwork

 

When it comes to the safety of construction projects, the formwork system is vital

Dangerous occur due to:

often need to work at height,

panels are heavy for human worker unstable formwork erection will cause collapse and harm people working on it

working area nearby the formwork is usually congested and not easy to get access into.

 

formwork

How is Classification of Formwork

 

  • Sizes, Location of use, Materials of construction, Nature of operation, Brand name of the products.

 

formwork

2.1 Classification according to sizes small-sized formwork

– operation by workers manually

– timber and aluminum large-sized formwork

– crane facilities are required in the operation- reduce the number of jointing and minimize the number of lifts.

– stiffening components – studs and soldier.

 

2.2 Classification according to the location of use

Using formwork for different elements of a structure has different design and performance requirements.

Some systems are more adaptive for specific locations of use, such as Irregular frame structures traditional timber form or aluminum form Cross Wall – gang form, climb form or jump form Floor – table form Repeated regular section – tunnel form

according to materials of construction

 

formwork

Timber – most popular formwork material

– low initial cost

– high adaptability to complicated shape

– labour intensive and environmentally unfriendly

 

formwork

Steel – hot-rolled or cold-formed sections

– heavyweight

– suitable for large-sized panels

aluminium - formwork

Aluminum – stiff and lightweight

– higher material and labour cost
– excellent finish

source: by Raymond Wong, Division of Building Science and Technology, City University of Hong Kong