|Construction Safety and Health
|U.S. Department of Labor
OSHA Office of Training and Education
The Occupational Safety and Health Administration's standard, Subpart Q, Concrete and Masonry Construction, Title 29 of the Code of Federal Regulations (CFR), Part 1926.700 through 706, sets forth requirements with which construction employers must comply to protect construction workers from accidents and injuries resulting from the premature removal of formwork, the failure to brace masonry walls, the failure to support precast panels, the inadvertent operation of equipment, and the failure to guard reinforcing steel.
NEW FORMAT FOR SUBPART Q
Subpart Q is divided into the following major groups each of which is discussed in more detail in the following paragraphs:
SCOPE AND APPLICATION
The standard, Subpart Q, prescribes performance-oriented requirements designed to help protect all construction workers from the hazards associated with concrete and masonry construction operations at construction, demolition, alteration or repair worksites. Other relevant provisions in both general industry and construction standards (29 CFR Parts 1910 and 1926) also apply to these operations.
Employers must not place construction loads on a concrete structure or portion of a concrete structure unless the employer determines, based on information received from a person who is qualified in structural design, that the structure or portion of the structure is capable of supporting the intended loads.
All protruding reinforcing steel, onto and into which employees could fall, must be guarded to eliminate the hazard of impalement.
Employees (except those essential to the post-tensioning operations) must not be permitted to be behind the jack during tensioning operations.
Signs and barriers must be erected to limit employee access to the post- tensioning area during tensioning operations.
Employees must not be permitted to ride concrete buckets.
Working Under Loads
Employees must not be permitted to work under concrete buckets while the buckets are being elevated or lowered into position.
To the extent practicable, elevated concrete buckets must be routed so that no employee or the fewest employees possible are exposed to the hazards associated with falling concrete buckets.
Personal Protective Equipment
Employees must not be permitted to apply a cement, sand, and water mixture through a pneumatic hose unless they are wearing protective head and face equipment.
Employees must not be permitted to place or tie reinforcing steel more than 6 feet above any adjacent working surfaces unless they are protected by the use of a safety belt or equivalent fall protection meeting the criteria in OSHA standards on Personal Protective and Life Saving Equipment (29 CFR 1926 Subpart E).
Equipment and Tools
The standard also includes requirements for the following equipment and operations:
- Bulk cement storage,
- Concrete mixers,
- Power concrete trowels,
- Concrete buggies,
- Concrete pumping systems,
- Concrete buckets,
- Bull floats,
- Masonry saws, and
- Lockout/tagout procedures.
General Requirements for Formwork
Formwork must be designed, fabricated, erected, supported, braced, and maintained so that it will be capable of supporting without failure all vertical and lateral loads that might be applied to the formwork. As indicated in the Appendix to the standard, formwork that is designed, fabricated, erected, supported, braced and maintained in conformance with Sections 6 and 7 of the American National Standard for Construction and Demolition Operations - Concrete and Masonry Work (ANSI A10.9-1983) also meets the requirements of this paragraph.
Drawings or Plans
Drawings and plans, including all revisions for the jack layout, formwork (including shoring equipment), working decks and scaffolds, must be available at the jobsite.
Shoring and Reshoring
All shoring equipment (including equipment used in reshoring operations) must be inspected prior to erection to determine that the equipment meets the requirements specified in the formwork drawings.
Damaged shoring equipment must not be used for shoring. Erected shoring equipment must be inspected immediately prior to, during, and immediately after concrete placement. Shoring equipment that is found to be damaged or weakened after erection must be immediately reinforced.
- Designed by a qualified designer and the erected shoring must be inspected by an engineer qualified in structural design,
- Vertically aligned,
- Spliced to prevent misalignment, and
- Adequately braced in two mutually perpendicular directions at the splice level. Each tier also must be diagonally braced in the same two directions.
Adjustment of single-post shores to raise formwork must not be made after the placement of concrete.
Reshoring must be erected, as the original forms and shores are removed, whenever the concrete is required to support loads in excess of its capacity.
Vertical Slip Forms
The steel rods or pipes on which jacks climb or by which the forms are lifted must be (1) specifically designed for that purpose and (2) adequately braced where not encased in concrete. Forms must be designed to prevent excessive distortion of the structure during the jacking operation. Jacks and vertical supports must be positioned in such a manner that the loads do not exceed the rated capacity of the jacks.
The jacks or other lifting devices must be provided with mechanical dogs or other automatic holding devices to support the slip forms whenever failure of the power supply or lifting mechanisms occurs.
The form structure must be maintained within all design tolerances specified for plumpness during the jacking operation.
The predetermined safe rate of lift must not be exceeded.
All vertical slip forms must be provided with scaffolds or work platforms where employees are required to work or pass.
Reinforcing steel for walls, piers, columns, and similar vertical structures must be adequately supported to prevent overturning and collapse.
Employers must take measures to prevent unrolled wire mesh from recoiling. Such measures may include, but are not limited to, securing each end of the roll or turning over the roll.
Removal of Formwork
- The plans and specifications stipulate conditions for removal of forms and shores, and such conditions have been followed, or
- The concrete has been properly tested with an appropriate American Society for Testing and Materials (ASTM) standard test method designed to indicate the concrete compressive strength, and the test results indicate that the concrete has gained sufficient strength to support its weight and superimposed loads.
Reshoring must not be removed until the concrete being supported has attained adequate strength to support its weight and all loads in place upon it.
Precast concrete wall units, structural framing, and tilt-up wall panels must be adequately supported to prevent overturning and to prevent collapse until permanent connections are completed.
Lifting inserts that are embedded or otherwise attached to tilt-up wall panels must be capable of supporting at least two times the maximum intended load applied or transmitted to them; lifting inserts for other precast members must be capable of supporting four times the load.
Only essential employees are permitted under precast concrete that is being lifted or tilted into position.
- Lift-slab operations must be designed and planned by a registered professional engineer who has experience in lift-slab construction. Such plans and designs must be implemented by the employer and must include detailed instructions and sketches indicating the prescribed method of erection. The plans and designs must also include provisions for ensuring lateral stability of the building/structure during construction.
- Jacking equipment must be capable of supporting at least two and one-half times the load being lifted during jacking operations and the equipment must not be overloaded. For the purpose of this provision, jacking equipment includes any load bearing component that is used to carry out the lifting operation(s). Such equipment includes, but is not limited to, the following: threaded rods, lifting attachments, lifting nuts, hook-up collars, T-caps, shearheads, columns, and footings.
- No employee, except those essential to the jacking operation, must be permitted in the building/structure while any jacking operation is taking place unless the building/structure has been reinforced sufficiently to ensure its integrity during erection. The phrase "reinforced sufficiently to ensure its integrity" used in this paragraph means that a registered professional engineer, independent of the engineer who designed and planned the lifting operation, has determined from the plans that if there is a loss of support at any jack location, that loss will be confined to that location and the structure as a whole will remain stable.
- Under no circumstances must any employee who is not essential to the jacking operation be permitted immediately beneath a slab while it is being lifted.
- Equal to the height of the wall to be constructed plus 4 feet, and shall run the entire length of the wall;
- On the side of the wall that will be unscaffolded;
- Restricted to entry only by employees actively engaged in constructing the wall; and
- Kept in place until the wall is adequately supported to prevent overturning and collapse unless the height of wall is more than 8 feet and unsupported; in which case, it must be braced. The bracing must remain in place until permanent supporting elements of the structure are in place.
OSHA's revised standard includes the following important changes:
- Expands and toughens protection against masonry wall collapses by requiring bracing and a limited access zone prior to the construction of a wall;
- Permits employers to use several more recently developed methods of testing concrete instead of just the one currently recognized method; and
- Sets and clarifies requirements for both cast-in-place concrete and precast concrete during construction.
Compliance with the common-sense requirements of the OSHA standard discussed here should greatly reduce or eliminate the injuries and accidents that occur too frequently during concrete and masonry construction.