Showing posts with label Prestressed Concrete Box Girder Bridges. Show all posts
Showing posts with label Prestressed Concrete Box Girder Bridges. Show all posts

Thursday, June 19, 2014

Alameda County, California Bridges: 580-238 Interchange

June 2014 (37.690452, -122.098853) 580-238 Interchange
In the photo above the E580-S238 Connector OC (33 0436F) can be seen straddling over the W580-N238 Connector Sep. (33 0525G). Today's bridge uses outrigger bents to step over an obstacle. Yesterday's bridge used outrigger bents to reduce the length of the bents on a big skew. Outriggers are nice but they're hard to design since there's less room to develop the reinforcement into the joints. This interchange was designed just prior to the 1989 Loma Prieta Earthquake, which demonstrated that knee joints have to be carefully designed for the opening and closing moments that can occur.
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Alameda County, California Bridges: 580-238 Interchange by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Friday, December 6, 2013

Napa County, California Bridges: West Imola Avenue Bridges across the Napa River (2)

December 2013 (38.278576 Degrees, -122.280795) West Imola Avenue Bridges
The West Imola Avenue (State Route 121) Bridges cross over a wide flood plain along the Napa River. The area east of the river is a 'Habitat Recovery Project' where they are trying to coax original species back to the wetlands. The bridges also cross the Napa Valley Railroad and the Napa River trail (with their own bridges across Tulucay Creek).
The West Imola Avenue Bridges are supported by single column bents with wide flares. The bridges are 2142 ft long with 150 ft long river spans. The bridges include walkways and are 45 ft from edge of deck to edge of deck. Minimum vertical clearance is 60 ft above the river.
The bridges have a sufficiency rating of 81.5, which seems low for seven year old bridges. The decks scored 6 out 9, but they looked okay when we drove across. Napa Valley has no expressways taking travelers east and west and rush hour traffic is particularly bad, especially on the previously studied Napa River Bridge. Traffic on the West Imola Avenue Bridges was 16,000 vehicles a day but that was counted when the bridges were first opened to traffic.
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Napa County, California Bridges: West Imola Avenue Bridges across the Napa River (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Thursday, December 5, 2013

Napa County, California Bridges: West Imola Avenue Bridges across the Napa River (1)

December 2013 (38.278576 Degrees, -122.280795 Degrees) West Imola Avenue Bridge
Just north of yesterday's Napa River Bridge are the West Imola Avenue/Napa River Bridges (21 0108R/L). They are two 13 span prestressed concrete cast-in-place box girder bridges that were built in 2007. Even though these bridges are a somewhat cookie-cutter design, I like the streamlined shape of the barrier rail openings, the column flares, the tapered girder ends, and the sloping lamp posts. We'll take a closer look at these bridges tomorrow.
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Napa County, California Bridges: West Imola Avenue Bridges across the Napa River (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Thursday, July 11, 2013

Yolo County, California Bridges: I-5 Bridges across the Yolo Bypass

July 2013 (38.67500 Degrees, -121.65667 Degrees) Yolo Bypass Bridges
The Yolo Bypass protects Sacramento from flooding by allowing the Sacramento River to spill over the Fremont Weir and fill a low lying area with water during the winter (see Google earth map below).
Several long viaducts cross over the Yolo Bypass. Just west of the Elkhorn Bridge that we studied yesterday are the 8,711 ft long I-5 Bridges over Yolo Bypass (22 0124L/R). They are prestressed concrete, cast-in-place, box girder bridges that were built in 1969.
The superstructures sit on drop bent caps supported on pile extensions. These bridges are in much better shape than the adjacent Elkhorn Bridges and have a sufficiency rating of 89.1.
The surrounding land is lush green rice fields, mostly owned by the Conaway Ranch with signs warning trespassers (like me) that deputized guards will arrest us.

Rice is an important commodity in this part of Yolo County and the nearby Port of Sacramento ships rice all over the world.
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Yolo County, California Bridges: I-5 Bridges across the Yolo Bypass by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Friday, January 4, 2013

Nevada County, California Bridges: Interstate 80 Bridges across the Truckee River

December 2012 (39.3838 Degrees, -120.0819 Degrees) I-80 Bridges
Next to the Hirschdale Bridges are the I-80 Bridges (17-0059L/R) that cross Hirschdale Road, the Truckee River, and two pair of railroad tracks. The seven and eight span (1018 ft long and 1088 ft long) prestressed box girder bridges were built in 1989.

I like the narrow tapered piers with the recessed, textured center. A little extra effort can turn an ordinary looking bridge into a structure with light and shadow and a little style.
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Nevada County, California Bridges: Interstate 80 Bridges across the Truckee River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Tuesday, April 6, 2010

California Bridges - El Curtola Road Overcrossing

I like bridges with unusual supports. El Curtola Road Overcrossing goes over State Route 24 and the center pier spans over the Bay Area Rapid Transit (BART) tracks between Orinda and Walnut Creek.

This bridge has a two-span prestressed concrete box girder superstructure, end diaphragm abutments on large diameter piles, and a battered two column bent.

This bridge was recently retrofitted to survive a large earthquake (after this photo was taken). Since battered columns will take longitudinal displacement as an axial force, the columns must resist the earthquake with brute strength. Therefore, the reinforced concrete columns were encased in steel.
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California Bridges - El Curtola Road Overcrossing by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Friday, December 4, 2009

Mexico's Bridges: Puente Atenquique I (4)

Another view of Puente Atenquique with the inactive Nevado de Colima in the background. More information on this volcano and the highly active Vulcon de Fuego de Colima is available on Wikipedia.

Bridge engineers now have a variety of construction tools for building long, tall structures.

Bridges can have both segmentally constructed substructures and superstructures. They can use prefabricated girders or the girders can be cast-in-place using advancing forms. Suspension bridges, cable-stayed bridges, and long prestressed girder bridges can all be built segmentally. Truss bridges can also be built segmentally, although fewer are being built today. Incrementally launched bridges can also use precast or cast-in-place segments.

I wonder if it's possible to build an incrementally launched arch bridge?
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Mexico's Bridges: Puente Atenquique l (4) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Thursday, December 3, 2009

Mexico's Bridges: Puente Atenquique I (3)

Another incrementally-launched post-tensioned box girder bridge built in 1989 by Mexpresa on Route 54D in Colima Mexico.

The bridge seems to be in pretty good shape, although I wonder why those tendons/rebars are sticking out of the side of the box?

I imagine that the columns were segmentally constructed. A certain length of column forms were put together, the concrete is poured and cured, and then the forms were raised and additional concrete poured above the cold joint. This process was repeated until the column was completed.

I wonder if the entire rebar cage is first assembled.  It may be difficult to assemble and support a 250 ft tall rebar cage while the concrete is poured, but it's certainly possible.

The box girder superstructure was assembled just like the superstructure on Puente Atenquique II. The concrete was poured in units between a quarter to a half of the span length and then pushed out from the abutment. A steel nose was attached at the end to provide support from the next pier. The hydraulic jack must be well anchored to be able to push a bridge all the way to the other abutment. I think the development of hydraulic jacks has 'revolutionized' the art and practice of bridge engineering.
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Mexico's Bridges: Puente Atenquique I (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Tuesday, December 1, 2009

Mexico's Bridges: Puente Atenquique I (1)

Rio Atenquique is quite meandering, and so about a mile north of the Puente Atenquique II it crosses under Puente Atenquique I.

I don't know why the sign for Puente Atenquique I shows a segmentally-constructed bridge with haunched girders. Most likely, the sign painter wasn't that knowledgeable about bridges. However, it's actually another incrementally-launched bridge like Puente Atenquique II. It only has seven spans though. It's a 320 m (1050 ft) long bridge, 75 m (246 ft) above the river, and with a 10.5 m (34.5 ft) wide deck.

Note the enormous road cut at back of this photo. Puente Atenquique is just beyond the cut. We have seen that the engineers who designed Route 54D always cut the top of the rise and then build a bridge over the subsequent valley. This makes the highway a little easier to drive, especially for someone (like me) who drives a Prius.
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Mexico's Bridges: Puente Atenquique I (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Monday, November 30, 2009

Mexico's Bridges: Puente Atenquique II (4)

A look at an abutment on Puente Atenquique II. I would guess that this is not the abutment from which the superstructure was launched, because the soffit looks like it rode over eight piers and the end looks like it carried the steel guide.

I would guess that the square blocks on the front of the abutment stem wall are decorative although its possible they could have supported some equipment while the bridge was being launched. The shear keys seem slightly ineffective since there's such a big space between the girder web and the keys. The long overhangs would be riding on the top of the keys before the box girder ever got near it. Still that might be sufficient to prevent the superstructure from moving very far transversely.

The back wall looks like it is right up against the superstructure which can't be right, unless this is an extremely warm day, which I'm pretty sure isn't true.

The superstructure is supported on special  bearings with a teflon or stainless steel top surface that allows the soffit to slide with a minimum of friction for the 1/4 mile over the piers. This type of bearing is specially designed for incrementally launched bridges. The nose attached to the end of the superstructure is long enough to prevent large cantilever moments when the span is hanging half-way between supports.
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Mexico's Bridges: Puente Atenquique II (4) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Sunday, November 29, 2009

Mexico's Bridges: Puente Atenquique II (3)

Another view of Puente Atenquique II. It looks like a lubricant was applied to the bridge soffit to help the superstructure slide. There's also stains on the side of the superstructure, perhaps from the bridge launching system. You can see that the bridge is very straight, which must make launching the bridge easier (although I understand that bridges with horizontal curves are also built using incremental launching).

Mexico has many incrementally-launched bridges. The company Mexpresa has a website showing some of the incrementally-launched bridges they've built, beginning in 1978 with Puente Rio Tula in Hidalgo.

It looks like the pier closest to the viewer is somewhat stouter than the others, although I'm not sure why. Also, it appears that the bridge was built over a rock quarry. Note that the end of the bridge is at a road cut. The bridges must be at the top of grades and the cut material must be put at the bottom.
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Mexico's Bridges: Puente Atenquique II (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Saturday, November 28, 2009

Mexico's Bridges: Puente Atenquique II (2)

A closer look at the superstructure of Puente Atenquique II on Route 54D in Jalisco, Mexico.

I found this bridge referenced in Structurae. It was built in 1989, it has a 10.5 m (34.5 ft) wide deck, and it was build by incremental launching. We saw this technique used to build the Pont Charles de Gaulle in my blog of April 11, 2009. Although that was a steel bridge, the technique is similar. Box girder segments were cast behind the abutment, cured, and then pushed out with hydraulic jacks. It seems incredible to me that this 1/4 mile long bridge could be pushed out from one abutment!  It must have had a very high camber to have been cantilevered out so far without deflecting below the top of the pier!

A short article on incremental launching of bridges provided by the University of California at Berkeley is available on the Internet.  It looks as though a special nose is put on the end of the superstructure to help it get over the piers.

Note the squat bearings between the top of the piers and the bridge soffit. The superstructure must be able to slide on these bearings as it is pushed out across the canyon. Also note the rebar sticking out of the side of the superstructure. There must be a vertical diaphragm, perhaps at the end of each segment. I imagine each precast segment was pushed out and then post-tensioning tendons were attached to the next piece, which was also pushed out, until a completely post-tensioned superstructure reaches the other side of the canyon.
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Mexico's Bridges: Puente Atenquique II (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Friday, November 27, 2009

Mexico's Bridges: Puente Atenquique II (1)

I skipped past a single span bridge (Puente Los Hornos) and another space-truss structure (Puente El Nuevo) to arrive at the incrementally launched box girder bridge,  Puente Atenquique II. It has a continuous nine span superstructure on single column bents and seat-type abutments.

I looked up Atenquique and found that it is a town with a tragic history. Heavy rains in 1955 caused a flash flood that drowned many members of the community as they were attending Mass. It is also the name of the stream that runs under this structure.

The bridge is 83 m (272 ft) tall and 440 m  (1445 ft) long. Like the other continuous superstructure bridges spanning wide canyons on Route 54D, this structure is a single prestressed box girder with long, gull-wing overhangs. A 1445 ft continuous superstructure is extreme long not to have an intermediate expansion joint. The superstructure is supported on sliding bearings that allows it to expand and contract without flexing the very tall piers. The 17 inch thermal movement must be addressed by very large expansion joints at each abutment.

We'll take another look at this bridge tomorrow.
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Mexico's Bridges: Puente Atenquique II (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Tuesday, November 17, 2009

Mexico's Bridges: Viaduct Beltran (1)

A few miles further north on Route 54D (between Colima and Guadalajara) are a series of extremely long bridges supported on extremely tall piers.

Viaduct Beltran is an odd four-span bridge. The first pier is supported at the bottom of a ravine, making it many times taller than if it had been moved farther or closer to the first abutment. The second pier is actually two bents placed twenty feet apart. My feeling is that the superstructure is balanced on the two bents, but the first abutment was too far away so they had to support it on the long first pier.

I imagine the superstructure was segmentally constructed. It's a haunched, prestressed concrete, box girder bridge. The superstructure is continuous, but it just sits on the piers (with a downward projecting element between transverse shear keys).

We'll take another look at this interesting bridge tomorrow and I welcome your thoughts or any information you may have on it. I wonder how long the spans are and how tall the first pier is?
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Sunday, October 18, 2009

American River Bridges: Lake Natoma Crossing

Because of all the traffic problems on the Rainbow Bridge, the City of Folsom built the Lake Natoma Crossing just downstream in 1999. It is a 2300 ft long prestressed concrete box girder bridge. It includes three 328 ft long haunched girder spans over Lake Natoma, which was formed by Nimbus Dam just downstream from Folsom Dam. It provides four vehicle lanes, two bike lanes, and pedestrian walkways, and takes some of the traffic off the Rainbow Bridge.

There are several interesting features on this bridge. For one thing it was designed with a lot of community input, which included the appearance of the bridge. There are a lot of embellishments reflecting the City of Folsom's 19th century appearance (brackets supporting the bridge overhangs and Victorian bridge columns). However, the most controversial element is the decorative arches that serve no purpose except to resemble the arch on the Rainbow Bridge just upstream. To me this is intellectually dishonest and gives the bridge an overdecorated appearance. Apparently HDR (the designers) couldn't get a real arch bridge to work with the seismic and other restraints and offered this as a solution. It does match the overdecorated style of the Victorian era, although the parabolic shape seems more modern.

The other interesting feature is the seismic design. The columns are supported on large-diameter pile shafts embedded into rock. The top of the columns have isolation bearings that allow the superstructure to move during an earthquake without putting large demands on the columns. Moreover, the superstructure was made with lightweight concrete to reduce the inertial force to the bearings.

The bridge reflects the needs of the community and the various compromises that had to be made between the demands of nature and society. However, I don't think that Ayn Rand/ Howard Roark would approve.
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Thursday, October 15, 2009

American River Bridges: Folsom Dam Bridge


We must travel about sixteen miles downstream from the No Hands Bridge along the American River and past Folsom Lake to reach the next bridge, which was just completed a few months ago. The Folsom Dam Bridge was built because Homeland Security didn't want the public to drive on large dams after 9/11.

A friend just sent me some photos of a new bridge they're building across the Colorado River so that no one drives over the Hoover Dam. Similarly, after 9/11, people were prevented from driving over Folsom Dam, creating a traffic nightmare, that was eventually solved when the Folsom Dam Bridge was build a few hundred yards downstream.

I'm in no position to judge how serious a threat terrorists blowing up a dam is to U.S. security. I know that after 9/11, people came up to me occasionally and asked me why I was photographing a bridge, as if I was planning to blow it up! I thought that was being a little paranoid, but I'm probably in the minority. Anyway, more bridges means more work for bridge engineers!

I photographed this bridge (without a tripod) using auto-bracketing to create three images that were merged together in Photoshop to create a high-density-range (HDR) photo. However, I think the color looks a little strange. I rode my bike seventeen miles from my house along the American River Bike Trail to the bridge last Saturday. I was surprised by the razor wire on top of the fence (that ruined the photograph) but that's a small price to pay to be secure I guess.

As you can see, its a continuous, three-span, prestressed concrete box girder bridge on squat columns that look like an unfortunate choice for earthquake country. Caltrans requires spirals or hoops for transverse reinforcement, but these columns look like they're built with stirrups and ties. Well, this isn't a highly seismic area, and the bridge had to be reviewed by Caltrans, so it's probably okay.

In the computer graphics used as public relations for the bridge they show hikers and cyclists along the bike trail without any fences or razor wire to obscure the view.
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