STD. 12.01 - Bridge Manual - Abutment Type A1 (Integral Abutment) - Reinforcement and Seat Details

Oct 23, 2026

Standard drawing and notes for bridge abutment design, focused on Abutment Type A1 (integral abutment) with fixed and semi-expansion seats. Specifies maximum laps and splice bases for horizontal bars, epoxy coating for wing and dowel bars, piling spacing constraints, and rules for concrete placement under water per section 502.3.5.3. Provides beam seat slope handling using longitudinal grade and camber effect, waterproofing and joint seal requirements, and detailing of reinforcement bar sizes and spacing by girder and slab span conditions.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages11

Reading Time28 min

AccessFree to download

STD. 12.01 - Live load and load factors

Abutment Type A1 - Fixed and semi-expansion seat details

Piling spacing, laps, coatings, and concrete placement

Beam seat slope, camber effect, and span-based reinforcement

| DESIGNER NOTES | | | | | --- | --- | --- | --- | | 8 '-0 " MAX
| | LAP LENGTHS FOR HORIZONTAL BARS SHALL BE BASED ON A "CLASS C" TOP TENSION LAP
SPLICE.
WING BARS AND DOWEL BARS SHALL BE EPOXY COATED.
PILING SPACING IN ABUTMENT BODY SHALL BE 8'-0" MAX. FOR ALL TYPES OF PILING. THE MAX. PILE SPACING FROM THE END OF THE ABUT. BODY TO THE FIRST PILE SHALL BE THE MINIMUM OF
ONE-HALF PILE SPACE OR 2'-6".
TOTAL LENGTH OF A1 BARS SHALL BE > TO WING LENGTH.
CONCRETE POURED UNDER WATER WILL BE ALLOWED AND SHALL BE DONE IN ACCORDANCE WITH SECTION 502.3.5.3 STANDARD SPECIFICATIONS.
THE SEMI-EXPANSION SEAT SHALL BE USED WHEN REQUIRED AS STATED IN CHAPTER 12,
FIGURE 12.7-1 OF THE BRIDGE MANUAL OR WHENEVER A WING PILE IS REQUIRED.
THE FIXED SEAT CANNOT BE USED WHEN A WING PILE IS REQUIRED (SEE STD. 12.02 FOR CRITERIA) .
WHEN THE BOTTOM OF GIRDER SLOPES MORE THAN 1%, SLOPE THE BEAM SEAT BASED ON ADDING THESE TWO VALUES:
-LONGITUDINAL GRADE OF GIRDER (PERCENT)
-CAMBER EFFECT = 4(RC)/L X 100 (PERCENT), WHERE:
RC = RESIDUAL CAMBER (INCHES)
L = GIRDER LENGTH (INCHES)(SEE STANDARD 13.01 FOR SLOPED SEAT DETAILS)
ABUTMENT DETAILED WITHOUT STRUCTURAL APPROACH SLAB. SEE STD. 12.10 THRU 12.13 FOR STRUCTURAL APPROACH DETAILS.
USE THIS SHEET FOR BEAM SEAT DETAILS (WITH OR WITHOUT A STRUCTURAL APPROACH SLAB) .
USE 34" THICK FILLER FOR SLAB STRUCTURES.
| | | | | | LEGEND
\#5 BARS (COATED) AT 1'-0" CENTERS X 2'-0" LONG, EMBED 1'-0". THESE BARS MAYBE PLACED AFTER CONCRETE IS POURED BUT BEFORE INITIAL SET HAS TAKEN PLACE.
WHEN THIS DIMENSION > 4" THIS ADDITIONAL REINFORCEMENT SHALL BE ADDED. MAX. SPA. OF HORIZ. \#4 BARS = 1'-0".
USE 1'-3" FOR SLAB SPANS AND FOR GIRDER SPANS WITH NO PAVING NOTCH.
USE 1'-6" FOR GIRDER SPANS WITH NO PAVING NOTCH, BUT WHERE 36W", 45W", 54", 54W", 70", 72W" OR 82W" GIRDERS ARE USED, AND SKEW > 25° .
USE 1'-3" FOR SLAB SPANS WITH A PAVING NOTCH, BUT NO STRUCTURAL APPROACH SLAB.
USE 1'-11" FOR GIRDER SPANS WITH A PAVING NOTCH, BUT NO STRUCTURAL | | TYPE A1 WITH FIXED SEAT SEMI-EXPANSION SEAT

|

LOCATION OF WING PILE ~~ ~~

BEARING PAD

1'-3"
3'-3"
6'-6"
1'-6"

DIMENSION IS FROM BOTTOM OF ABUTMENT TO LOW BEAM SEAT OR LOW SIDE OF SLAB TYPE SUPERSTRUCTURE.
18" RUBBERIZED MEMBRANE WATERPROOFING. SEAL ALL HORIZONTAL AND VERTICAL JOINTS ON BACKFACE.
KEYED CONST. JOINT FORMED BY BEVELED 2" X 6".
USE \#5 BARS AT 6" SPA. IN OUTSIDE THIRDS OF BODY LENGTH WHEN THE WING LENGTH > 20'-0" AND WING HEIGHT > 10'-0".

JOINT. RUN BAR STEEL THRU JOINT AND SEAL JOINT WITH 18" RUBBERIZED MEMBRANE WATERPROOFING. SEE STD. 12.09 FOR ALTERNATE CONSTRUCTION JOINT.

W BARS ~~ ~~SEE STD. 12.02 TABLE A

SHOW ALL BARS FOR CLARITY.

APPROACH SLAB.
USE 1'-7" FOR SLAB SPANS WITH A STRUCTURAL APPROACH SLAB. (STD. 12. 10) USE 2'-3" FOR GIRDER SPANS WITH A STRUCTURAL APPROACH SLAB. (STD. 12. 10)
STD. HOOK
NO SLOPE FOR HEAVY RIPRAP. SEE STANDARD 12.08 FOR DETAILS.
WING WITH PILE
WHEN BODY SECTION IS > 50'-0" +
LONG
PROVIDE
VERTICAL CONSTRUCTION
WINGWALL WIDTH SHALL BE 1'-6" WHEN TYPE "M" RAILING, VERTICAL FACE PARAPET "TX", OR SINGLE SLOPE PARAPET "56SS" IS USED. "56SS" SHOULD NOT BE USED ON A SIDEWALK. WINGWALL WIDTH SHALL BE 1'-4" WHEN PARAPET 'A' ON A RAISED SIDEWALK IS USED. WINGWALL WIDTH SHALL BE 1'-9"WHEN TYPE "NY3" OR "NY4" RAILING IS USED. (USE 2'-0" WIDTH WHEN "NY4"IS USED ON A SIDEWALK) .

12" FILLER-TO EXTEND FROM BRIDGE SEAT TO TOP
OF CONCRETE PARAPET OR TO TOP OF WING FOR STEEL | | | |
12" FILLER-TO EXTEND ~~ ~~FROM BRIDGE SEAT TO TOP OF CONCRETE PARAPET OR TO TOP OF WING FOR STEEL RAILINGS. FILLER INCLUDED IN WING LENGTH

ABUTMENT TYPE A1 (INTEGRAL ABUTMENT)

1

34" CORK FILLER ON VERTICAL

RAILINGS. FILLER INCLUDED IN WING

FAQs

What governs lap lengths and splices for horizontal bars in this standard?

Lap lengths for horizontal bars are based on a class C top tension lap splice.

When must the semi-expansion seat be used, and when is the fixed seat disallowed?

The semi-expansion seat is used when required as stated in Chapter 12, Figure 12.7-1, or whenever a wing pile is required. The fixed seat cannot be used when a wing pile is required.

How is the beam seat base shaped when the bottom of the girder slopes more than 1%?

Slope the beam seat based on adding the longitudinal girder grade (percent) and the camber effect calculated as 4(RC)/L × 100 (percent), with RC in inches and L in inches.

Oct 23, 2026

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