Lecture 17

Sub-structure:Design of the Abutments

A counter-fort retaining wall.

The next step is to calculate the dead weight value w(x) from the superstructure and part of the sub-structure. It can also include some live load if the bridge is in a heavily traveled urban area. From these two values, vs and w(x), we can find the fundamental period T of the bridge and the seismic force pe(x).

12'-0

"

5'-6

"12"

12"

3'-0

"

2 '-6" 12" 3'-6"

1'-6

"

7 '-0"

4'-0

" 6'-0

"

9"

12"

A

5

72

8

4

1

3

6

3.88'

L =5.26 k

L =0.24 kv

h

e

P

BackfillGirder

aa

Abutment

Approach slabNormal pavement

Bridge slab

Wheel load

31

12"

16'-6

"

2'1'

-6"

3' 1'-6" 5'-6"

Ver

t. ba

rs,

Ver

t. ba

rs, b

ack

face

back

face

#6 @

5"

#6 @

10"

Provide 3" clear to all bars except 11

2 " clear to bars in front face of stem

#4 @ 2'-0"

6" drains @ 10'-0"

#6 @ 6" 2"x6" key

#6 @ 6"

#4 @ 12"

#4@ 9" front face #4@18" back face

Preparing the foundations of an abutment for a high-speed rail overpass (AVE, St, Sadurniu, Barcelona. The AVE is the high-speed rail connection between Paris-Barcelona).

The almost finished abutment for a high-speed rail overpass (AVE, St, Sadurniu, Barcelona. The AVE is the high-speed rail connection between Paris-Barcelona).

Abutments damaged by seismic forces

San Fernando Earthquake, on February 9, 1971. Settlement of the abutment fill.

Wing-wall damage at abutment

Interchange 210 – RoxfordStreet Undercrossing at Foothill Boulevard.

Single-span, variable depth, prestressed box girder, slightly skewed and supported on pile diaphragm abutments. The structure was supported entirely on fill. All eight wingwall-to-diaphragm connections were badly damaged.

Failure in Shear of Superstructure and End Diaphragm at Soffit.

Balboa Boulevard Over-crossing –South Abutment

Seven-span, reinforced concrete box girder with Class II piles and spread footings. Abutments were diaphragm type.

The south abutment was in original ground and soil supported, while the north abutment was upon fill and supported on concrete piles.

Abutment Fill Settlement

Eureka Earthquake –November 8, 1980.

Epicenter – 30 miles northwest of Eureka, CA

Magnitude – 6.6 to 7.1 on the Richter Scale

Damage – Collapse of Fields Landing Overhead located on Highway 101

Aerial View of Fields Landing showing Collapse of Two Spans. Failure caused by earthquake factors which can be attributed to the failure caused by severe skew, rocker bearings at the abutments, hinges at each bent, narrow hinge seats, simply-supported median slab between tan not connected to left and right bridge.

Abutment 1.

All of the pedestals were severely shattered, and most of the steel bearings were ripped from their anchorages.

Steel rocker bearings were torn out of their anchors.

Damage to abutment and to the wingwall.

Route 14/5 Separation & Overhead Route 14/5 Separation & Overhead –– Collapsed Spans at South AbutmentCollapsed Spans at South Abutment

Higashi-Kobe Bridge – Vertical Movement of 0.5 Meter at the Top Roadway.

Failure of Reinforcing Concrete Pier Wall

Hanshin Expressway – Failure of single-column bents