Form work, Scaffolding & shoring : Form work, Scaffolding & shoring MUHAMMAD AMMAR General : General For the different construction activities like
Brick work above 5 ft
Surface finishing works like plastering, painting, walling etc.
Renovation, repair and alteration works.
Roof and slab pouring
Some temporary nature supports and structures are required like
Formwork (Supporting Structure)
Scaffoldings (arrangement for working plate forms)
Shoring (supporting method for unsafe structure)
Underpinning (Method of strengthening an existing
structure’s footing) Form work : Form work Definition
Qualities of formwork
Types of formwork
Formwork detail for different structural members
Removal of formwork
Maintenance of formwork
Cost of formwork
Advantages of steel form work Definition : Definition Its is an artificial support provided below and around the precast or cast insitue concrete work.
Formwork is commonly made of
Formwork construction & casting is of prime importance in concrete industry. It share a significant amount of concrete cost.
Formwork is designed according to The ACI document SP-4. It can be purchased from www.concrete.org Qualities of formwork : Qualities of formwork It should be according to ACI document SP-4
It should be water tight
It should be strong
It can be reusable
Its contact surface should be uniform
It should be according to the size of member. Types of formwork : Types of formwork Formwork are mainly of two types
Steel formwork is made of
Wooden formwork consists of
sheeting Formwork detail for different structural members : Formwork detail for different structural members In concrete construction formwork is commonly provided for the following structural members.
Slabs & beams
Stairs Formwork for Foundations : Formwork for Foundations Wall foundations
It consists of
Struts Formwork for Foundations : Formwork for Foundations Column Foundations
It consists of
Cleats Side Support Side Planks Cleats Formwork for Wall : Formwork for Wall It consists of
After completing one side of formwork reinforcement is provided at the place then the second side formwork is provided. Vertical Posts Struts Formwork for Column : Formwork for Column It consists of the following
Side & End Planks
Nut & Bolts
Two end & two side planks are joined by the yokes and bolts. Column form work : Column form work Formwork for Slabs & beams : Formwork for Slabs & beams It consists of
Beam formwork rests on head tree
Slab form work rests on battens and joists
If prop height are more than 8’ provide horizontal braces. Lintel or Beam Formwork : Lintel or Beam Formwork Formwork for Stairs : Formwork for Stairs It consists of
Vertical & inclined posts
Wooden Planks or sheeting
Riser Planks Riser Planks Removal of formwork : Removal of formwork Time of formwork removal depends on the following factors
Type of Cement
Rapid hardening cements require lesser time as compared to OPC (Ordinary Portland Cement)
Ratio of concrete mix
Rich ratio concrete gain strength earlier as compared to weak ratio concrete.
Hydration process accelerates in hot weather conditions as compared to cold and humid weather conditions. Time of Removal of formwork : Time of Removal of formwork Maintenance of formwork : Maintenance of formwork Due to continuous use wooden planks & steel plates surfaces become uneven and require maintenance.
For wooden formwork use cardboard or plastic fiber board. Bolt hole places must also be repaired.
For steel formwork plates must be leveled by mallet and loose corners must be welded. Cost of formwork : Cost of formwork For normal works cost of formwork is about 30%-40% of the concrete cost.
For special works cost of formwork is about 50%-60% of the concrete cost.
Formwork cost is controlled by the following factors
Formwork Material cost
Formwork erecting cost
Formwork removal cost
Formwork jointing cost (Nails and Cables)
Labor charges. Advantages of steel form work : Advantages of steel form work It can be used for a no. of times.
It is non absorbent.
Smooth finish surface obtained.
No shrinkage of formwork occurs.
Easy to use.
Its volume is less
Its strength is more. Scaffolding : Scaffolding Definitions
It’s a temporary structure to provide a platform at different levels of a building for workers and Materials. Types of Scaffolding : Types of Scaffolding Following are the types of scaffolds
Steel or Tubular Scaffolds Definition : Definition Scaffold
It is the temporary support system provided for the construction & maintenance purposes.
It consists of supports and a working platform for workers and Materials.
Method of construction of scaffolds is called scaffolding. Single Scaffolds : Single Scaffolds It consists of
Standards (v posts)(10 cm)
Putlogs (7.5 x 7.5)
Used for ordinary buildings 1.2 m Double Scaffolds : Double Scaffolds It consists of
Two rows of standards.
15 cm, 1.5 m
Shores are provided.
Used for superior works Ladder Scaffolds : Ladder Scaffolds It consists of
Brackets for Plate form. Cantilever Scaffolds : Cantilever Scaffolds It consists of
It is used above ground level Suspended Scaffolds : Suspended Scaffolds It consists of
Ropes can be raised Manually or mechanically
Used for light construction and finishing works of multistory buildings. Steel or Tubular Scaffolds : Steel or Tubular Scaffolds It consists of
Steel tubes (1-1/2” – 2-1/2” diameter)
Coupler or Clamps (to hold pipes in different positions)
Prop nuts (to hold single pipes)
Bolts, Nuts & washers
Wedge & Clip Scaffold pipes : Scaffold pipes Coupler or Clamps : Coupler or Clamps Scaffold fittings : Scaffold fittings Double Coupler
It joins ledgers and standards.
Composed of two single couplers and used to join two scaffolds at any angle.
Used to join putlogs with transom.
Used at the base of the standards.
Split joint Pin
It’s a connection fitting used to join scaffold tubes.
It fit in to the end of a tube to form an adjustable strut.
A flat plate used at the end of a scaffold to convert it in to a putlog. Scaffold fittings : Scaffold fittings Scaffold fittings : Scaffold fittings Prop nuts, clamp and fasteners : Prop nuts, clamp and fasteners Wedge & Clip : Wedge & Clip Standards : Standards BS 1139:Part 2:Section 2.1 (working scaffolds and false work made of steel tubes )
NZ 3620 Scaffold Planks
AS 1576 Scaffolding Web links for Scaffolding : Web links for Scaffolding http://www.advancescaffold.com/international-standard.html
http://www.bhanuudyog.com/product.htm# Shoring : Shoring Definition
It is the method of providing temporary support (shores) to an unsafe structure.
Types of Shoring
Horizontal shoring or flying shoring
Vertical shoring or dead shoring
Inclined Shoring or flying shoring Horizontal shoring : Horizontal shoring It consists of
Horizontal beam or strut
Used to support two adjacent buildings. Single Flying Shoring : Single Flying Shoring Double Flying Shoring : Double Flying Shoring Vertical shoring : Vertical shoring It consists of
Used for rebuilding of walls. Dead or Vertical Shoring : Dead or Vertical Shoring Inclined Shoring : Inclined Shoring It consists of
Used to strengthen a wall. Inclined or Raking Shoring : Inclined or Raking Shoring Inclined or Raking Shoring (unsymmetrical) : Inclined or Raking Shoring (unsymmetrical) Raking Shoring Details : Raking Shoring Details Raking Shoring Details : Raking Shoring Details Inclined Shoring or Raking Shoring : Inclined Shoring or Raking Shoring Under-Pinning : Under-Pinning Definition
Methods of Under-Pinning
Pile method Pit method : Pit method Old wall is supported by a bearing plate, steel beam and jacks.
Excavation up to new depth is carried out.
Foundation is provided for small 5’ (1.5 m) lengths.
P.C.C (1:2:4) is provided for new foundation.
For proper joint b/w old and new work, strengthening and to avoid settlement vertical steel bars may be added. Steel Bars Pile method : Pile method Slide 59: ACI Document SP-4 Back Kicker or Starter : Kicker or Starter Inverted Beams : Inverted Beams