5-157 Payment will be made under: P a y I t e m Pay Unit
527.34 Work Zone Crash Cushions Unit
SECTION 528 - STRUCTURAL TIMBER Reserved SECTION 529 - NAVIGATIONAL AIDS Reserved SECTIONS 531 to 533 – VACANT SECTION 534 - PRECAST STRUCTURAL CONCRETE
534.01 Description The Contractor shall design, manufacture, f urnish, and install
precast structural concrete arches, box culverts or three sided frames and associated wingwalls, headwalls, toe walls, cut-off walls and appurtenance s, in accordance with the Contract Documents.
534.02 Materials Structural precast elements for the arch, box culvert, or three sided
frame and associated precast elements shall meet the requiremen ts of the following Standard Specification Subsection, except as noted otherwise in this spe cification: Structural Precast Concrete Units 712.061 New concrete mix designs and mix designs not previously approve d by the Fabrication Engineer shall be qualified by trial batches prepared in accord ance with AASHTO T 126 (ASTM C192). The test results shall demonstrate that the concr ete meets the requirements of the Contract Documents. Bedding and backfill material shall conform to the requirements of Standard Specification 703.19, Granular Borrow, Material for Underwater Backfill, with the additional requirement that the maximum particle size shall be limited to 4 inches, or as shown on the Plans.
534.03 Drawings Prepare shop detail, erection and other necess ary Working Drawings
in accordance with Standard Specification Section 105.7, Workin g Drawings. The Department will review the drawings in accordance with the appl icable requirements of Section 105.7, Working Drawings. Changes and revisions to the reviewed Working Drawings shall require further review by the Fabrication Engine er. Working Drawings shall include the following minimum details: 5-158
1.Fully dimensioned views showing the geometry of the units, i ncluding all projections, recesses, notches, openings, block outs, keyways a nd chamfers.
2.Details and bending schedules of reinforcing steel including the size, spacing, and location. Reinforcing provided under lifting devices shall be shown in detail.
3.Details and locations of all items to be embedded. 4. Total weight of each unit. Concrete mix designs shall be pa rt of the Working Drawing submi ttal. Include aggregate specific gravity, absorption, percent fracture, finen ess modulus and gradation as part of the mix design. Provide the mix design calculations de monstrating how the batch weights, water-cement ratio and admixture dosage rate were dete rmined.
534.04 Design Requirements The C ontractor shall design the pr ecast structural
concrete structure in accordance with the AASHTO LRFD Bridge De sign Specifications, latest edition. The HL-93 live load specified in the AASHTO LRF D Bridge Design Specifications shall be used for all limit states, except for S trength I. The live load used for the Strength I limit state shall be the Maine Modified live loa d, which consists of the standard HL-93 Live Load with a 25 percent increase in the Desi gn Truck only. (Wheel loads based on the Design Truck shall be increased 25 percent). Additionally, if the governing load rating factor based on the HL-93 live load is eq ual to or less than 1.10 and the span is 14 feet, or greater, then a load rating based on th e Maine legal truck (Configuration #6) shall also be checked to insure the rating f actor is equal to, or greater than, 1.0. The live load deflection check, per AASHTO LRFD Bridge Design S pecifications, for the top slab of box culverts and frames with clear spans of 15 feet, or greater, and cover depths of 4 feet, or less, is mandatory. The live load deflec tion check shall be documented in the design computations submittal. Design calculations that consist of computer program generated output shall be supplemented with at least one hand calculation and graphics de monstrating the design methodology used. The hand calculation shall document, at a min imum, the Strength I load case flexural design check of the top slab positive moment rein forcing steel. Design calculations shall provide thorough documentation of the source s of equations used and material properties. The design shall be load rated in accordance with the AASHTO Ma nual for Bridge Evaluation, latest edition, by the LRFR method and in accordanc e with the Department Load Rating Guide. The Contractor shall submit design calculations and load rating , if applicable, for the precast structure to the Department for review. A Professional Engineer, licensed in accordance with State of Maine laws, shall sign and seal all de sign calculations and drawings.
Source: Maine Standard Specifications for Road and Bridge Construction, 2020 Edition. Pages 449–450 of 817.