Presentation on theme: "CONCRETE AND MASONRY CONSTRUCTION"— Presentation transcript:
1 CONCRETE AND MASONRY CONSTRUCTION 29 CFR SUBPART QCONCRETE AND MASONRY CONSTRUCTION
2 Cooling Tower St. Mary’s West Virginia 1978 51 killed170 feet above groundEntire form peeled away from newly placed concrete
3 looked like if it had been completed. What the St. Mary’s West Virginia tower would havelooked like if it had been completed.
4 Jump forms atop the St. Mary’s structure tore loose, pulling work platforms and concrete down inside the tower.
5 Wreckage 168 feet below the top of the St 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.
6 Part 1926 Subpart Q Concrete and Masonry Construction Scope, application, and definitions applicable to this subpart.General requirementsRequirements for equipment and tools.Requirements for cast-in-place Concrete.App - General Requirements for FormworkRequirements for precast concrete.Requirements for lift-slab operations.App - Lift Slab OperationsRequirements for masonry construction.
7 29 CFR 1926 700 Scope, application, and definitions applicable to this subpart. "Bull float""Formwork""Lift slab""Limited access zone""Precast concrete""Reshoring""Shore""Vertical slip forms"“Jacking operation”
8 29 CFR 1926.701 General requirements (a) Construction loads.(b) Reinforcing steel.(c) Post-tensioning operations.(d) Riding concrete buckets.(e) Working under loads.(f) Personal protective equipment.
9 (b) All protruding reinforcing steel, onto and into which employees could fall,shall be guarded to eliminate the hazard of impalement.
16 1926.702 (b) Concrete mixers with one cubic yard or larger loading shall be equipped with: A mechanical device to clear the skip of materialsGuardrails installed on each side of the skip
17 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.
18 (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.
20 (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.
21 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.
22 1926.702(d) Concrete buggy handles shall not extend beyond the wheels on either side of the buggy
23 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.
31 1926.703 Shoring & re-shoring Inspected prior to erection Damaged equipment shall not be usedInspected immediately prior to, during, and immediately after concrete placement.
32 1926.703 (b) Shoring & re-shoring Equipment found to be damaged or weakened,shall be immediatelyreinforced.Sills shall be sound, rigid, and capable of carrying maximum intended load.(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.
33 (b)(8)Single post shoresDesign prepared by qualified designerVertically alignedSpliced to prevent movementBraced in two mutuallyperpendicular directions atsplice levelEach tier diagonally braced in the same two directions
37 (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 jackingProvided with scaffolds orwork platform whereemployees required to passJacks and lifting devicesprovided with mechanical dogs or other automatic holding devicesForm structure maintained within all design tolerances - for plumpness during jacking operations
38 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.
41 Pre-cast Concrete.(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
46 29 CFR 1926.705 lift-slab operations. (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
47 29 CFR 1926.705 lift-slab operations. (continued) (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
48 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.
49 Seal blockJack rodSpearhead framecast in floor slabLiftingangleWedgeWedge block
50 1926.705(a) Lift-slab operations shall be designed by a registered professional engineer who has experience in lift-slab construction.
52 1926.705 Jack lifting unit (b) Marked to indicate rated capacity (c) Not loaded beyond capacity(d) Two and 1/2 times the load(e) Designed so they neither liftnor continue to lift when they areloaded in excess to rated capacity(f) Synchronized lifting to ensureuniform lifting(g) Leveling device installed ( allpoints 1/2 inch tolerance)(h) Stop device (exceeds 1/2 inchtolerance)(i) Manual controls located in central location - attended by competent person (must be experienced)(j) Maximum number of annuallycontrolled units
58 29 CFR 1926.706 Masonry construction. a) Limited access zoneprior to the start of construction of the wallequal to the height of the wall to reconstructed plus four feet, and shall run the entire length of the wallon the side of the wall which will be un-scaffoldedrestricted to entry by employees actively engaged in constructing the wallshall remain in place until the wall is adequately supported(b) All masonry walls over eight feet in height shall be adequately braced
59 1926.706(a) Limited access zone Established prior to the start of constructionEqual to the height of the wall plus four feetUnscaffolded side of wallRemain until adequately supportedMasonry walls over 8 feet adequately braced