South Carolina - Bridges

Key Concepts

Falsework/form design loads (SCDOT 702.4.1.2, p. 543). Use not less than 150 lb/ft³ for normal concrete and not less than 120 lb/ft³ for lightweight concrete. Live load: actual equipment/personnel as concentrated loads plus a uniform load of not less than 20 psf over the supported area, plus 75 pounds per linear foot at the outside edge of deck overhangs. Horizontal: actual loads plus an assumed wind load of not less than 50 psf of horizontal surface area or 2% of total dead and live load, whichever is greater. Falsework settlement is limited to 1 inch or less.

Designated inspector qualifications (702.4.1.4.4, p. 544). Minimum 5 years supervisory experience in bridge construction or an Engineering degree and 4 years of experience in structural design or bridge construction.

Key Concepts

Bar types, grades and identification - The bar number is the nominal diameter in eighths of an inch (#8 = 1 in.); metric numbers are approximate diameter in mm (Ch. 6, Table 6.1). - Bars are normally furnished in Grades 60 (420) and 75 (520); Grades 80 (550) and 100 (690) are also available (Ch. 6, pp. 94–95). - All deformed bars carry rolled-in marks for producer's mill, bar size, type of steel, and grade. The Grade 60 (420) mark may be either the number 60 (4) or one single line (an extra rib) (pp. 94–95). - Fiber-reinforced concrete under ASTM C1116/C1116M: Type I = steel, Type II = glass, Type III = synthetic (Ch. 6, FRC section). - SCDOT 703.2.1: rebar and dowels meet ASTM A 706, minimum single yield 60,000 psi (Grade 60), from SCDOT Qualified Product List 60; acceptance is based on 30-inch long field samples tested by the…

Key Concepts

Cost and definition. Formwork costs range from 35 to 60 percent of the cost of a concrete structure (Contractor's Guide, p. 54). Formwork is the total system of support for freshly placed concrete — facing material, supporting members, hardware, and bracing (p. 54; also OSHA 29 CFR 1926.700(b)(2)).

Lateral pressure. The three most important variables affecting pressure on forms are concrete temperature, rate of placement, and weight of concrete (p. 70). Classification matters: a wall has at least one plan dimension greater than 6.5 ft (2 m); a column has no plan dimension larger than 6.5 ft (p. 71). Retarders raise the chemistry coefficient CC to 1.2 versus 1.0 for cement without retarder (p. 72).

Key Concepts

OSHA Subpart R — Scope and controlling contractor - The subpart covers steel erection on buildings, bridges and other structures but does not cover electrical transmission towers, communication and broadcast towers, or tanks (§1926.750(a)). - Before erection begins, the controlling contractor must give the steel erector written notification that concrete/mortar in footings, piers and walls has attained 75 percent of the intended minimum compressive design strength (ASTM field-cured sample test) or sufficient strength to support erection loads (§1926.752(a)(1) and (b)). - The controlling contractor must bar other construction processes below steel erection unless overhead protection is provided (§1926.759(b); duty also listed at §1926.750(c)). - Critical lift = a lift exceeding 75 percent of the rated capacity of the crane or derrick, or requiring more than one crane or derrick (§1926.751).

Key Concepts

SC 811 / Underground Facility Damage Prevention Act - Normal (non-subaqueous) notice must be given 3 to 12 full working days before the proposed commencement date (Section 58-36-60(A); Manual p. 54). - Subaqueous notice requires 10 to 20 full working days for member operators to respond (Section 58-36-60(A); Manual p. 13, pp. 54-55). - Locators have 3 full working days to respond to a normal locate request; the life of the request begins the day after the request at 12:00 am (Manual p. 13). - A notice expires 15 working days after the date of notice; no excavation may continue after that period without a subsequent notice (Section 58-36-60(B); Manual pp. 15, 55). - Tolerance Zone: one-half the known diameter plus 24 inches on either side of the designated center line (Section 58-36-20(21)(a); Manual pp. 28, 46). - Pre-marking must be done exclusively with white paint, flags or stakes (Section 58-36-60(E)(1); Manual…

Sources: SCDOT Standard Specifications, Sections 401, 409, 501, 502.

Key Concepts

PCC placement and mixing (Section 501) - Elapsed time (501.4.7.1.3, p. 266): time from addition of water to deposit in place must not exceed 30 minutes in non-agitating trucks and 60 minutes in truck mixers or truck agitators. The RCE may allow a slight increase only under unusual conditions if slump (without re-tempering) is not less than the average for concrete previously placed and the concrete is otherwise satisfactory. - Central plant mixing time (501.4.7.1.1): mixers rated greater than 2 cubic yards mix at least 90 seconds; add any charging time in excess of 20 seconds. The RCE, with the SME, may decrease to 60 seconds. Overloads up to 10% above nominal capacity may be permitted (501.4.7.1.2). - Weather (501.4.6, p. 265): no concrete operations until shade air temperature away from artificial heat is at least 35ºF and rising and is predicted by…

Key Concepts

Employer responsibilities / competent person - The employer must initiate and maintain programs necessary to comply with Part 1926, and those programs must provide for frequent and regular inspections of job sites, materials, and equipment by competent persons designated by the employer (§1926.20(b)(1)–(2)). - "The employer shall permit only those employees qualified by training or experience to operate equipment and machinery" (§1926.20(b)(4)). - Noncomplying machinery, tools, material or equipment are prohibited and must be tagged/locked out as unsafe or physically removed (§1926.20(b)(3)). - Competent person: one capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them (§1926.32(f)). No degree, years of experience or certificate is in that definition. Compare qualified (recognized degree, certificate, professional standing, or extensive knowledge/training/experience) (§1926.32(m)) and authorized person (§1926.32(d)). - PPE: the employer is responsible…

Key Concepts

Measurement of quantities (Subsection 109.1, pp. 74–76) - All work is measured by the RCE using United States Standard Measures; a station is 100 linear feet (109.1(1)–(2), p. 74). - Unless otherwise specified, longitudinal measurements for area computations are made along the actual surface of the roadway, and no deductions are made for individual fixtures having an area of 9 square feet or less. Transverse measurements are the neat dimensions shown on the Plans or authorized by the RCE (109.1(4), p. 74). - Structures are measured to neat lines on the Plans or as altered to fit field conditions (109.1(5)). Linear-foot items (curb and gutter, fence, pipe culverts, guardrail) are measured parallel to the base of foundation unless otherwise specified (109.1(6)). - Excavation volumes use the average end area method or other acceptable methods; excavation beyond neat lines or slope stakes is not measured for payment except when the material is used…

Exam: South Carolina – Bridges

Key Concepts

Units of measurement (Subsection 109.1, Pages 74–75) - A station, when used as a definition or term of measurement, is 100 linear feet (109.1, Page 74). - "Ton" means the short ton of 2,000 pounds avoir. (109.1, Page 74). - Cement is measured by sack or bag or by the ton; the terms "sack" or "bag" mean the traditional 94 lb. bag size (109.1, Page 75). - Items measured by the linear foot (curb and gutter, fence, pipe culverts, guardrail, etc.) are measured parallel to the base of foundation upon which the item is placed or attached unless otherwise specified (109.1, Page 74). - Structures are measured according to neat lines shown on the Plans or as altered to fit field conditions (109.1, Page 74). - No deductions are made for individual fixtures having an area of 9 square feet or less (109.1, Page 74). - Timber:…