Beam Forming Formwork
Theory
Formwork, a temporary structure which supports its own weight, temporary loads like equipment, workmen while placing the concrete until it gains necessary strength. Beam forming Formwork comes under Horizontal Formwork. In beam forming formwork, there are traditional methods, proprietary form methods.
Traditional Method
In traditional method, normally we use sheathing of 1.2 m x 2.4 m of plywood between 12 to 19 mm thickness. Joists are 100 mm x 100 mm lumber spaced between 300 mm to 400 mm on the center with a spanning distance of 1.2 m to 1.8 m. Stringers are of 100 mm x150 mm timber with spans from less than 1m to 1.5m. Shores size will be 100 mm x100 mm. Horizontal bracings will be there to stabilize the form.
Proprietary Form Method
In proprietary form methods, beam form methods from construction giants like L&T. We also have MIVAN formwork, PERI system. Based on the requirement, we will select the formwork system by giving some weightage for other parameters that effects the project.
L&T flex formwork is used for form heights less than 4.1 m. As the maximum prop height is 4.1m only. If the height is more, then we can go with L&T Heavy Duty Tower. HD towers are self-supportive and has higher load capacity. Takes lesser time for erection and dismantling compared to flex formwork.
Traditional method type is labor intensive and time consuming work. It demands skilled labor. Sometimes additional effort is required after stripping of formwork. The chance of casualties at the site is more compared to other proprietary form methods.
Materials Required
- Sheathing: Plywood is used as sheathing. This will be directly in contact with concrete.
- Timber Beam: Usually H20 or H16 timber beams is used based on the requirement. It will be directly in contact with sheathing. The load of concrete transferred from sheathing to this timber beams.
- Aluminium Beam: These are secondary members takes the load from Timber beams. These will be placed perpendicular to timber beams.
- CT Props: These are props that can be adjusted to various heights as per our requirement. L&T Compactable Telescopic Props of various sizes are CT410, CT340, CT300, CT250.
- Bracings: These are used diagonally and horizontally to hold the props in place and stabilize the formwork.
- Nails, Bolts: Bolts are used to join the bracings with props. We attach sheathing with timber beams by nailing.
- Base Plate& U head: Base plate will act as base to props. U head is used to hold the Aluminium beams. Load transfers from aluminium beams to Props by U head.
- Beam Forming Support with Extension (BFS): Used to support the vertical side of beam. We use extension because the support height will be less than the beam depth.
Note:
- Before starting the formwork, the area should be clean. A plain area is supposed to be taken because working on plane platform will be easier. The formwork materials should be handled properly.
- Apply form coating agent to new sheathing atleast 36 hours before being used. A second application should then be made before being used for the first time.