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29 CFR 1926 SUBPART Q CONCRETE AND MASONRY CONSTRUCTION. Cooling Tower St. Mary’s West Virginia 1978. 51 killed 170 feet above ground Entire form peeled away from newly placed concrete. What the St. Mary’s West Virginia tower would have looked like if it had been completed.
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29 CFR 1926 SUBPART Q CONCRETE AND MASONRY CONSTRUCTION
Cooling TowerSt. Mary’s West Virginia 1978 • 51 killed • 170 feet above ground • Entire form peeled away from newly placed concrete
What the St. Mary’s West Virginia tower would have looked like if it had been completed.
Jump forms atop the St. Mary’s structure tore loose, pulling work platforms and concrete down inside the tower.
Wreckage 168 feet below the top of the St. Mary’s tower being picked apart by investigators looking for clues. The state of West Virginia objected to the site being cleaned before it could make its own full investigation.
Part 1926 Subpart QConcrete and Masonry Construction • 1926.703 App - General Requirements for Formwork • 1926.704 - Requirements for precast concrete. • 1926.705 - Requirements for lift-slab operations. • 1926.705 App - Lift Slab Operations • 1926.706 - Requirements for masonry construction. • 1926.700 - Scope, application, and definitions applicable to this subpart. • 1926.701 - General requirements • 1926.702 - Requirements for equipment and tools. • 1926.703 - Requirements for cast-in-place Concrete.
"Bull float" "Formwork" "Lift slab" "Limited access zone" "Precast concrete" "Reshoring" "Shore" "Vertical slip forms" “Jacking operation” 29 CFR 1926 700 Scope, application, and definitions applicable to this subpart.
29 CFR 1926.701General requirements • (a) Construction loads. • (b) Reinforcing steel. • (c) Post-tensioning operations. • (d) Riding concrete buckets. • (e) Working under loads. • (f) Personal protective equipment.
1926.701(b) All protruding reinforcing steel, onto and into which employees could fall,shall be guarded to eliminate the hazard of impalement.
1926.701(c) - Post-tensioning operations No employee (except those essential to the post-tensioning operations) shall be permitted to be behind the jack during tensioning operations
1926.701(d) Riding concrete buckets No employee shall be permitted to ride concrete buckets.
(a) Bulk cement storage. (b) Concrete mixers. (c) Power concrete trowels. (d) Concrete buggies. (e) Concrete pumping systems. (f) Concrete buckets. (g) Tremies. (h) Bull floats. (i) Masonry saws. (j) Lockout/Tagout procedures. 702 Equipment and Tools.
1926.702 (b) Concrete mixers with one cubic yard or larger loading shall be equipped with: • A mechanical device to clear the skip of materials • Guardrails installed on each side of the skip
Pumping System 1926.702(e) (1) Concrete pumping systems shall be provided with pipe supports designed for 100 percent overload. (2) Air hoses shall be provided with positive fail-safe joint connectors.
1926.702(g) Tremies. Sections of tremies and similar concrete conveyances shall be secured with wire rope (or equivalent materials) in addition to the regular couplings or connections.
Concrete piping system connection point
1926.702 (f) Concrete buckets (1) Concrete buckets equipped with pneumatic gates shall have positive safety latches or similar safety devices installed to prevent premature or accidental dumping. (2) Concrete buckets shall be designed to prevent concrete from hanging up on top and the sides.
1926.702 Power-concrete trowels Shall be equipped with a control switch that will automatically shut off the power whenever the hands of the operator are removed from the equipment handle.
1926.702(d) Concrete buggy handles shall not extend beyond the wheels on either side of the buggy
1926.702(i) (1)Masonry saws shall be guarded with a semicircular enclosure over the blade (2)A method of retaining blade fragments shall be incorporated in the design of the semicircular enclosure.
(a) General requirements for formwork. (b) Shoring and reshoring. (c) Vertical slip forms. (d) Reinforcing steel. (e) Removal of formwork. 29 CFR 1926.703 Cast-in-place Concrete.
1926.703 Shoring & re-shoring • Inspected prior to erection • Damaged equipment shall not be used • Inspected immediately prior to, during, and immediately after concrete placement.
1926.703 (b) Shoring & re-shoring • Equipment found to be damaged or weakened, • shall be immediately • reinforced. • Sills shall be sound, rigid, and capable of carrying maximum intended load. 1926.703(b)(6) All base plates, shore heads, extension devices, and adjustment screws shall be in firm contact, and secured when necessary, with the foundation and form.
1926.703(b)(8) • Single post shores • Design prepared by qualified designer • Vertically aligned • Spliced to prevent movement • Braced in two mutually • perpendicular directions at • splice level • Each tier diagonally braced in the same two directions
Ellis shoring system
1926.703(c) Vertical slip forms Jack rod Jack Thin pipe around jack rod Yoke assembly Splash board Working deck Wales Bracing for Wales Sheathing Slight batter of sheathing
1926.703(d) Vertical slip form Steel rods or pipes on which jacks climb shall be designed for that purpose and adequately braced when not encased in concrete. Designed to prevent excessive distortion during jacking Provided with scaffolds or work platform where employees required to pass Jacks and lifting devices provided with mechanical dogs or other automatic holding devices Form structure maintained within all design tolerances - for plumpness during jacking operations
1926.703 (e) Removal of formwork Shall not be removed until employer determines concrete has gained sufficient strength to support its weight and super imposed loads: Plans and specifications which stipulate conditions for removal of forms and shores; Concrete had been properly tested.
(a) Adequate support of wall units, structural framing, and tilt-up panels (b) Capability of inserts (c) Imbedded inserts (d) Lifting hardware (e) No employee under pre-cast concrete members being lifted or tilted into position except those employees required for the erection of those members 1926.704 Pre-cast Concrete.
Un pre-stressed slab Prestressed slab - unloaded Prestressed slab - loaded
(a) Lift-slab operations shall be designed and planned by a registered professional engineer (b) Jacks/lifting units shall be marked (c) Jacks/lifting units shall not be loaded beyond their rated capacity (d) Jacking equipment shall not be overloaded (e) Design and installation of jack lifting units 29 CFR 1926.705 lift-slab operations.
(f) Jacks/lifting units shall have a safety device installed (g) Jacking operations shall be synchronized (h) Automatic controlled leveling (i) Manually controlled leveling (j) Maximum number of manually controlled jacks/lifting units (k) Number of employees allowed in the building 29 CFR 1926.705 lift-slab operations. (continued)
(l) Temporary connections (m) Welding on temporary and permanent connections (n) Load transfer from jacks/lifting units to building columns (o) Securing Jacks/lifting units (p) Prevention of components from disengaging during lifting operations. 29 CFR 1926.705 lift-slab operations. (continued)
Seal block Jack rod Spearhead frame cast in floor slab Lifting angle Wedge Wedge block
1926.705(a) Lift-slab operations shall be designed by a registered professional engineer who has experience in lift-slab construction.