Lecture18 - Piers

7/28/2019 Lecture18 - Piers

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Lecture 18a

Sub-structure:

Design of Piers


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Pier for S-826 connector at NW 103 Street, Miami.


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Expansion of the deck from one-lane to two-lanes for the I-75 ramp from S-826 at Hialeah.


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The new piers for the I-494 WakotaBridge over the Mississippi River at South St Paul, Minnesota. The

new bridge consists of twin long-span, cast-in-place, segmental concrete bridges. Each bridge is 98 feet inwidth with five lanes and two full-width shoulders. The five spans clear 1,879 feet with the maximum spanof 466 feet. Substructure used 4 ksi concrete and the superstructure 6 ksi. Post-tensioning consists of 270-ksi seven wire super strand with 23 x 0.6 in-diam. strand tendons in the longitudinal direction and 4 x 0.6in-diam. strand tendons in the transverse direction. The piers shown above flare up to match the box girdersoffitand web incline angle. Note the icebreaker section. The box girders are attached to the stem walls

with the reinforcing steel from the stem wall extending into thebox girder diaphragm walls.


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Lake Maracaibossegmental box girder bridge.


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Seismic Effects upon Piers


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Route 5 (Truck Lane)/ 405 Separation. This was a cast-in-place pre-stressed box girder with two 177

spans on a curved skewed alignment. The bridge collapsed at thebent, which consisted of two columnswith #4 ties at 12. The structure was a complete loss and was immediately demolished and removed.


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San Fernando Road Overhead (Route 210). Two-span, cast-in-place pre-stressed concrete box girder

with single column bents. Approach fills settled on foot. Bridge sagged four feet at base due toshattering of column at base.


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San Fernando Road Overhead (Route 210) Column Failure. Close up of column base. Concretecore at base was lost and #18 bars buckled (ties were #4 @ 12). Structure was entirely replaced.


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Column shear and buckling failure at 5/210 Interchange Foothill Boulevard Underpass,

four-span reinforced concrete box girder with four column bents. Thesuperstructureappeared to have no damage.


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Column shear and buckling failure. Foothill Boulevard Under-crossing. Octagonal tied columns (#4@ 12 inches).


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Shear failure at the top ofthe column.Foothill Boulevard Under-crossing.


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Anchorage failure.

Route 210/ Separation &Overhead.

Bars pulled out of thepile shaft.


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Cypress Creek Viaduct, I-880, collapsed by the Loma PrietaEarthquake, Oakland, California.


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The Cypress Street Viaduct, I- 880 (Nimitz Freeway). This photo of the East side of freeway showsthe collapsed structure. The reinforced box girder structure had spans varying from 71 to 90 feet in

length (80 feet average). The curb-to-curb width of the bridge was approximately 52 feet. Thecolumns (both lower and upper level) were separated about 15 feet in height.


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Cypress Street Viaduct, I-880(NimitzFreeway).

Detailed view of the collapsedupper level, with the columnshowing longitudinal steel.

The confinement was #4 bars at12-inch spacing.

The hinge at the right was

retrofitted with cable restrainers.


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Cypress Street Viaduct, I-880 (Nimitz Freeway). Photo shows the East side of the freeway at 32ndStreet. The upper level column was tapered at the base and joined to the lower level column as ahinge connection. Note that the shear key and dowels are shown.


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Bull Creek Canyon Channel Bridge Failed columns by the channel paving.


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Mission-Gothic Under-crossing. Columnfailure under the architectural flare.


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La Cienega Venice under-crossing. Column failure.


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Fairfax Washington Under-crossing.

Column failure.


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J an. 1995 Earthquake. Map showing the Hanshin Expressway and thePort of Kobe City.


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Failure of the column connections and thecollapse of the super-structure spans.

Hanshin Expressway


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Hanshin Expressway.

Buckled steel piers.

Close-up of buckled portion of steel piers.


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Hanshin Expressway.

Shear failure of a massive rectangularreinforced concrete pier.


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Hanshin Expressway. Failure of the butt welds in the longitudinal reinforcement.


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Hanshin Expressway. Failure of the transverse confining reinforcement.


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Hanshin Expressway. Shear failure of a massive rectangular reinforced concrete pier.


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Hanshin Expressway. Pier failure.


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Hanshin Expressway. Failure of single pier bents.


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Bearings


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Hanshin Expressway. The spherical housing for the fixed bearing failed at the support for thearch bridge.


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Hanshin Expressway. Shear failure of bolts connecting the transverse keeper plate to the bearingassembly.

Hanshin Expressway.


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The new bearings delivered to the jobsiteto replace those that failed were in-kindtype replacements.

Lecture18 - Piers

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