Policies-Manuals

Georgia DOT Bridge Detailing Guide

The purpose of this guide is to offer information on bridge detailing that is not reflected in the Bridge Design Manual available on the R.O.A.D.S. web site. The Bridge Design memos contain further detailing information as well as design information that is also in the Bridge Design Manual. Eventually the memos and this page will be phased out and the Bridge Design Manual will contain all design and detailing guidance.

If you would like to be put on an electronic mailing list to receive notification of updates to this page please write. The same list will be used for this Guide and for the Manual, so you don't need to sign up separately.

Sample Plans. A few sets of sample DOT bridge plans have been posted to the ftp server. They are in .pdf format and also include a preliminary layout. There is a description of each set of plans in the same folder. ftp://ftp.dot.state.ga.us/DOTFTP/BridgeDesign/Detailing.

General Design Issues

Standard Sheets. Bridge Design's "Basic Drawings" which includes standard sheets and cells can be downloaded at the following: .

General Notes. Make sure you use the standard notes by running the BRNOTES05 program. The manual for this program (available at ftp://ftp.dot.state.ga.us/DOTFTP/ in the BridgeDesign/Alpha Server Programs/Manuals folder) now contains guidance on the use of general notes. The new program has eliminated unused notes, added a few new ones, updated the notes for 2001 spec references, and changed the sentence structure for imperative mood (changed from "the bridge shall be grooved" to "groove the bridge"). Please let Bill DuVall know if any information should be added or changed.

Title Blocks. The DOT title block is preferred. Consultants can put their logo on the sheet as well. Only the first sheet needs a PE stamp. Refer to state and US roads by route number without periods. Examples: "SR 15 OVER BIG CREEK", "SR 15 (US 341 & 441) OVER LITTLE RIVER". For concurrent US routes always denote the lower number first. Although interstates have state route numbers, just use the interstate number (e.g. I-75). Refer to county or city roads by route number with their common name in parentheses: "CR 298 (BUCKSNORT ROAD) OVER YELLOW RIVER". You might even do this in urban areas where the route number is not in common use: "SR 236 (LAVISTA ROAD) OVER I-285". If there are multiple state route numbers running concurrently, always use the one referenced in Maintenance's bridge inventory first and, if necessary, also whatever is used in the roadway plans (normally Maintenance uses the lowest route number available). For example "SR 15 & 29 OVER UNNAMED CREEK". The stream name should be the same as that used on USGS quad maps and in the hydro study. Usually we spell out "CREEK" and "RIVER" using up to two lines in the title block for the project description. If the bridge is entirely within a county, only show that county name in the title block even if the roadway project crosses the county line. If the bridge crosses a county line, show both counties (e.g. "BERRIEN-LANIER COUNTIES") with the county at the beginning of the bridge first. The date should be the month and year without a comma, "DECEMBER 2004". Consultants can put their intitials in the Drawn, Designed, and Checked boxes, but Design Group is for whichever DOT bridge group is managing the project, Reviewed is for the assistant office heads (WEI/WMD for Design Groups PSR, WEI, RAG, ACB; and WMD for groups SWW, LA, IAB, and MLC; but on Big Bridge projects (group EJC) this should be the consultant QA reviewer) and Approved is PVL.

Standards. Under Bridge Consists Of always make sure you have the latest dates for the Standards. Due to some tweaking of the guardrail attachment the following dates apply (some of these do not appear on the bridge plans, so make sure the roadway plans are current):

• Standard 3054 - End Post Standard 9/30/02
• Standard 4012C - Guardrail Connection at Bridge 3/21/03
• Standard 9017R - Reinforced Concrete Approach Slab 9/20/02

2001 Georgia Standard Specifications

Although the section numbers are the same as in the previous spec (500 for concrete, 520 for piling, etc.), the 2001 edition subsections have been completely revised. Therefore any reference to a section of the specs on your plans or in special provisions will have to be updated. Bridge Design should have a revised version of the cell library available soon but until then here are some places where you may need to update the cells and plans:

• Expansion joints in deck: change 833.01 to 833.2.01 and change 500.08.C to 500.3.05.F
• PSC Beam sheets diaphragm bar: change 507.04.D to 507.3.05.C and change 865.03.M to 865.2.01.B.12
• Bearing pad sheet end section: change 833.10 to 833.2.10

Many Special Provisions are now covered by the Specifications so they are no longer needed. These include the following:

• 442 Sealing Roadway and Bridge Joints
• 443 Elastomeric Profile Joint (Jeene Joint)
• 449 Bridge Deck Joint Seals With Elastomeric Concrete Headers (Evazote)
• 461 Resealing Roadway and Bridge Joint Cracks
• 542 Contractor re-design from T-Beam to AASHTO Type I Mod
• 833 Joint Fillers and Sealers

Contact Bill DuVall for help with bridge-related Special Provisions or to get the latest version. See this list of most possible bridge special provisions. This sheet is filled out by the Bridge Design office when they review your plans.

Preliminary Layouts

Very little structural design goes into a Preliminary Layout. Depths of beams for a given span length can be determined from design charts (available in the memos). Generally it is one sheet showing a plan and elevation view along with a few details and notes, esp. relating to the hydraulics. A second sheet showing a section and beam spacing is generally only needed with widenings and staged construction (NOTE: most consultant contracts require the section sheet, but you can always ask your liaison in Bridge Design to waive that requirement). We recommend the use of Bridge Design's user command developed for Microstation. It gives you a pretty good start and, once installed, can be run from the Microstation menu.

Roadway plans typically round the roadway grades to two or three decimal places which is not sufficient for setting bridge elevations, so always use a calculated slope. Hopefully roadway designers are setting their PVI elevations to even feet, tenths, or hundreths. Getting the grades to work out will require some coordination with the roadway designer.

Do not clutter the Preliminary Layout with shoulder and lane widths. Those are best left on the roadway plans. For grade separations the roadway underneath often has lanes and future lanes designated.

Because the Preliminary Layout is non-structural there are differences between it and the Plan and Elevation:

• Do not show the foundation below the groundline
• Do not show fixed and expansion bearings or expansion joints in the deck or barrier

Projects managed by the Consultant Design Office have slightly different requirements than those managed by Bridge Design:

• A Preliminary Layout Checklist (MS Word 2002, 37 kb, revised 06/19/02) must be completed, checked off by hand by at least the designer and one checker.
• When calling out the barrier width, do not show the word "BARRIER". Just show the dimension 1'-7 ½" from face of barrier to edge of deck. Final plans leave off the word "barrier" because the barrier is really 1'-6". Preliminary Layouts have always showed the word because the program that generates the layout puts it there.
• Show an approximate proposed bottom of beam elevation. This helps the reviewer know whether the bridge is clearance-limited and whether deeper beams (hence longer spans) are possible or not.
• It is okay (even preferred) to show a local scour hole around a bent to illustrate the difference between general and local scour. When spanning the stream make sure you plot in main channel scour and follow the shape of the streambed, rather than just connecting the scour depths at the bents on the banks.

Superstructure

Decks

Expansion joints at end of bridge. If you modify the size of the joint to use Evazote you need to include the evazote joint detail in your plans. An individual cell for this does not exist but you can make a detail by using just the longitudinal section detail (delete the transverse detail) from the bridge expansion joint cell and calling it "Section thru joint at end of bridge" (or designate the bent number if you're not modifying both ends). You do not need to include a table of temperatures and opening sizes as you would do at an intermediate bridge joint.

Waterproofing. At the joint between the end wall and end bent cap, the plans will now refer to Section 530 of the Georgia DOT Specifications and will require "waterproofing" instead of "3-ply waterproofing," allowing the use of composite waterproofing membranes. This is typically shown on the end wall section. [Memo 4.23]

Endwall bar details. Bar detailing is pretty much left up to the engineer. The 900 bars have always been a pain to detail, especially in the full-width section of endwall between the exterior beam and wingwall. Since that concrete is cosmetic it doesn't need much reinforcement and the 900B bar there can be detailed as straight, lapping with the 900A bar in the exterior bay (see attached sketch). This is not a requirement but is presented here just to make your life easier. Though Bridge Design feels like no reinforcement is needed at the front face of the concrete, you could put a No. 4 stirrup in that area as temperature steel, but it is difficult to show in the plans.

In visible areas make sure the edge beam is flush with the exterior beam face all the way to the bottom of the beam to give a smooth continuous look to the beams. In the exterior bay we detail a fillet in the bottom of the edge beam at the flange of the exterior beam. The slope is 1:1. This is done to make sure the concrete can flow into the bottom flange area of the beam.

For situations where you have an exterior bulb tee beam you need to add some additional steel at the end of the beam in the edge beam. This consists of an L-shaped no. 4 bar running vertically along the centerline of the end of the beam with a 1'-0" leg extending longitudinally back over the top of the beam. Also add a no. 4 bar that intersects this bar in front of the the top flange of the beam (see sketch). The sketch has been revised to show the no. 4 bar extending past the beam flange on one side to get embedment in the bulk of the edge beam concrete. This steel can be shown in the deck section though a cell should also be available soon. The intention is to keep otherwise unreinforced concrete along the exterior face from cracking off.

Reinforced Concrete T-Beams

T-beam bridges do not use shim plates. Instead the difference across the cap (different back and ahead steps are not used for T-beam spans) is made up with extra concrete on the high side of the cap. This is accomplished through a T-dimension as shown in the edge beam section cells. The T dimension is measured at the face of the cap and should be set to accommodate at least a half-inch of extra concrete on the low side (plus the bearing pad which is typically included in the T dimension to the top of cap). T dimensions are typically detailed to the nearest eighth of an inch.

In 2000 the ASTM spec A570 was discontinued and replaced with the ASTM A1011 spec so the reference to A570 in the bearing pad notes needs to be changed.

Substructure

Pier Caps

As in the end bent graphics program if you leave off bottom of cap elevations the intermediate bent graphics program will calculate them for you using the minimum amount of concrete. This doesn't work right (in fact neither does the drawing) if you have different back and ahead steps.

End Bents

Drainage. A note is being added to the end bent sheets to refer to Georgia Standard 9037 for drainage details required at end bents.

Piles

The total pay quantity for piling is rounded off to the nearest 10 feet. The anticipated length of a pile is from the top to the estimated tip (or the average estimated tip if a range is given). Include the effect of battering a pile. Make sure you do not include pile lengths where test piles will be used (note that test piles are longer than regular piles so don't just subtract out test pile lengths from your total). Always include a pay item for a load test for every type and size of pile used on the project. [Memo 8.14]

Ted Cashin,
Office of Consultant Design
(404)463-6135
(404)463-6136 Fax
ted.cashin@dot.state.ga.us