tallbridgeguy

Just like the title says, a pdf of “Prefabricated Bridge Elements in Japan and Europe.” Brought to you by the Federal Highway Adminstration. The report date says March 2005.

I wish I was one of the lucky ones sent to observe construction all over Japan and Europe. Maybe I need a better agent.

The concept of sustainability in bridge design is becoming a major issue. Architects (and others) have a certification program for “Leadership in Energy and Environmental Design” or Leed for short.

The purpose is to make the best structures, with environmental friendly products, that leave the smallest footprint possible. Bridge design doesn’t have a certification system yet but it will. (Email me and we can start one!)

Here is a short article in Aspire magazine about Green bridges.

I was asked to design a county bridge in my state. Counties typically use high abutment bridges to minimize the overall length of the bridge. if the bridge is under 40′ then they use non-prestressed precast deck panels.

High Abutment Bridge

The biggest benefit is the cost. A typical 40′ long by 28′ wide bridge costs just over $100,000. The bridge I designed has 2:1 berm slopes and is the DOT favorite spill-through abutment bridge. The advantages of the spill-through bridge are working in the dry, wider stream opening and because it is the most commonly built bridge, it has access to a lot of standard parts.

Spill-through Abutment Bridge

The biggest drawback is that it costs more and counties are strapped for cash. My ABC design should be built in 5 days but the cost will be closer to $200,000. Yikes!

Hoping everyone has a Happy Holiday and a great New Year.

A typical ABC pier can be built with two precast columns tied to concrete drilled shafts (or forget the precast columns and use the drilled shafts as the columns). Then tie the precast pier cap to the columns.

Of course this type of pier is only useful on land. The pier columns are typically not suitable for river environments because of ice and water loads. Also this type of frame pier suffers from non-redundancy (is that a word?). Meaning if one of the drilled shafts settles or gets hit by a vehicle the whole pier could fall down.

For this reason most DOTs like the idea of pile foundations.

Because the chances of multiple piles failing is rare.

The Mills Street Bridge was built in 2004. Here is a great overview of the process and directions for improvements.

Also includes information on the Mitchell Gulch bridge.

Some of the work the University of Wisconsin-Madison is doing. Includes a short video of a precast abutment being installed. The abutment is similar to some of the piers shown earlier, precast panels slid down onto steel piles.

You have to place the piles very accurately and lock the system together. A big problem is when you place this in a river channel. You have to excavate fairly deep and hold the water back.

I guess this is only news to me. It looks like Governor Patrick signed a $3 billion dollar bond (last August) ” to repair and replace approximately 250-300 bridges in Massachusetts.”

I thought this was interesting because a) it is a ton of money and b) I saw a job posted on the web for a structural Accelerated Bridge program engineer. ABC must be making strides if they are hiring engineers expressly for the ABC program. Maybe this isn’t a fad?

This powerpoint (big file), by Joseph Hanus, explains how the military would implement ABC.

My favorite quote,

Any rigid material cut to fit will be too long. When corrected, it will be too short.

Okay I have beaten the pier thingy to death but the point is your typical pier is constructed in one piece. (It may be several actually concrete pours but it is considered an cast-in- place integral pier with no joints.)

Imagine the pier sits on a rock river bed. No joints, no way for the water to get to the steel and the system works as a whole.

When you try for a ABC pier the first thing you are talking about (typically) is segmental construction. Meaning that the pier comes in pieces and you tie it together in the field.

So you have to fit the pier together and add compression, in the form of post tensioning, to make the system act together.

The joints are problematic. How do you make sure the water stays out and does not get to the post tensioning strands?

Realizing, if the strands go, the pier goes….