Constructs Column Formwork
Chapter C5 – Constructs Column Formwork
Topic 1 – Describe Column Form Systems
Key Competencies
The NOA for Carpenter (2013) identifies the required competencies (skills) for the task of constructing column formwork. These are:
- Determine size and location of column forms according to specifications and project drawings
- Select materials such as wood, steel and round concrete forms (Sonotube®) according to project drawings and formwork design
- Place formwork components such as chamfer strips, reveal strips, form liners and embeds, and ensure all are plumb, level, square, and accessible for finishing work
- Brace column formwork in multiple directions in order to stabilize the formwork, prevent any movement when placing concrete and ensure that it is plumb, level and square
- Apply templates in column formwork according to project drawings
- Inspect assembled formwork for deficiencies such as inadequate bracing, out of plumb and incorrect elevation (NOA, p. 39).
Concrete columns are used to support beams and slabs above grade. The location and sizing of columns can be determined from the blueprint. The main factors in determining column size are the amount of load they are to support and the distance between columns. Column formwork can be manufactured wood, steel, or composite panels, fibreform, or job built using formply and lumber. Three methods of cutting and fitting wood form material for columns:
- butt method
- chase around method
- overlap method
Source: https://commons.wikimedia.org/wiki/File:Column-formwork.JPG
Support and alignment of the formwork is provided by a column template at the base and by yokes (horizontally) and kickers(vertically). A collar is placed near the top of the form to attach bracing. Columns should be braced plumb in both directions. A series of columns can be connected to each other with lateral bracing known as lacing. Drop panels and capitals can be included at the top of the column form to distribute the bearing capacity over a greater area.
Form pressure will be greatest at the bottom of the form so spacing of yokes or clamps should be closer together near the bottom. Spacing will increase as you move up the column. Spacing will be provided by the engineer or manufacturer’s specifications. Rate of placement has the greatest effect on column formwork pressure.
Review Instruction Sheet (IS) on Brightspace:
FNDT 300 (2017) Commercial Formwork (p. 1 – 28):
- IS 1.2 Materials and Hardware Used for Column Forms
- IS 1.3 Methods of Forming Columns
- IS 1.4 Column Clamp Spacing Charts
Review Questions
- If the edges of plywood form material are not treated or protected from moisture, what may happen?
- List three advantages of using steel forms over wood forms.
- If a column is more than one panel wide, what should be used to keep the forms from spreading?
- When wood chamfer strips are cut from common boards, the ____ should face the concrete surface:
- Original surface of the wood
- Surface that was cut
- How are wood yokes held together at the corners when forming for columns?
- Why are column forms often subjected to much greater concrete pressures than wall forms?
- What is the purpose of vertical stiffeners on the outside of column sheathing?
- How far up from the bottom should the first yoke be placed?
- Why should concrete in column forms be placed at least several hours before slab or beam forms above the columns are filled full of concrete?
- The maximum pressure that can develop on a column form, regardless of the rate of placement is ____ PSF (if water reducers are not used) (found in Principles and Practices)
- A drop panel is sometimes used between a column capital and a flat concrete slab if a beam is not used in order to _______ over a larger area.