Scaffolding safety rules 3
To be continued:
NOMENCLATURE
1. Adjustment Screw - device composed of a threaded screw and an adjusting handle used for the vertical adjustment of the shoring
and formwork.
2. Base Plate - a device used to distribute the leg load.
3. Coupling Pin- an insert device used to align lifts or tiers vertically.
4. Cross-bracing - system of members connecting frames to make a tower structure.
5. Extension Device - any device used to obtain vertical adjustment of shoring towers other than an adjustment screw.
6. Factor of Safety - the ratio of ultimate load to the allowable load.
7. Formwork - the material used to give the required shape and support of poured concrete, consisting primarily of: Sheathing -
material which is in direct contact with the concrete. Joists - members which directly support sheathing. Stringers or ledgers -
members which directly support the joists.
8. Frame - the principal prefabricated structural unit in a tower.
9. Lifts or Tiers* - the number of frames stacked one above each other in a vertical direction.
10. Locking Device - a device used to secure the cross brace to the frame.
11. Safe Leg Load - that load which can safely be directly imposed on the frame leg.
12. Shoring Layout - an engineered drawing prepared prior to erection showing arrangement of equipment for proper shoring.
13. Sill or Mud Sill - a footing, usually wood, which distributes the vertical shoring loads to the ground or slab below.
14. Towers - a composite structure of frames, braces and accessories.
15. Ultimate Load - the maximum load which may be placed on a structure causing failure by buckling of column members or failure
of some other component.
* These terms can be used synonymously
INSPECTION OF SHORING EQUIPMENT PRIOR TO ERECTION
The three main areas of inspection are for rust, straightness of members and welds. This applies to all components of a shoring system.
1. Rust - Rusted shoring equipment may indicate abuse, neglect, or corrosion and, if severe, should not be used.
2. Straightness of members - Mishandling, trucking and storing may cause damage to shoring equipment. All members or parts of all
shoring components should be straight and free from bends, kinks or dents.
3. Welds - Equipment should be checked before use for damaged welds and any piece of equipment showing damaged welds or
rewelding beyond the original factory weld should not be used. The factory weld
reference pertains to location and quality of rewelds. While rust, straightness and welds are of primary concern, other component parts
should be checked.
4. Locking devices on frames and braces shall be in good working order, and if not, must be repaired or replaced prior to use.
5. Coupling pins must effectively align the frame legs.
6. Pivoted cross braces must have the center pivot securely in place.
SAFE BEARING LOADS FOR SOILS
Considering that the allowable loads (bearing) on various soils and rock range from less than 1000 p.s.f. (47.9 kN/m2 ) to more than 50,000 p.s.f. (2393.7 kN/m2 ) care should be exercised in determining the capacity of the soil for every shoring job, realizing that weather conditions can turn an otherwise suitable ground condition into a hazardous situation. As an example, dry clay with an allowable bearing capacity of 8,000 p.s.f. (383.0 kN/m2 ) could become very plastic after a rainfall and drop to less than 2,000 p.s.f. (95.8 kN/m2). Care should also be taken not to excessively disturb the soil. If fill is required in shored areas, a qualified engineer should be consulted as to materials and compaction.