Hybrid Composite Beams - aka people are clever

[Shannow]

Dunno if any of you remember some of the discussions on concrete design where I explained that you always consider the concrete on the tensile side to be broken, and the only things holding the tension are the reinforcing ?

The concrete itself can handle compressive loads without the reinforcing.

Clearly somebody who does some thinking though well why put all that heavy concrete on the side that's considered broken anyway, and just add to the load on eht bridge with useless broken concrete...



That's clever.

 

[OneEyeJack]

John Hillman the engineer that developed that composite beam used ideas and methods developed by French bridge engineers. The composite beam is an example of taking great engineering and making it better. Maybe Hillman's beams can be used to rebuild all the US bridges that are falling apart or getting condemned. The savings in construction time and concrete alone should help pay for the job. Our politicians have to just stop running off with the road tax money that's supposed to be used to maintain the roads and bridges.

 

[Rick in PA]

We use to have a local company, I think their name was Eastern Prestressed Concrete, that made prestressed beams. They made long beams with embedded steel reinforcement in the lower area of the beam. During casting of the concrete, the steel would be put under great tension. In service the concrete would mostly be in compression. I remember seeing these beams being trucked out of the facility on tractor trailers that could be extended in length. There would be flag cars before and after these oversized loads. It was quite a process.

Once, I met a fellow who worked there. He said every once in a while they'd have a bad beam. What to do? They took them out back, bulldozed a trench and buried it. I wonder if some future owner of the site is in for a surprise when they find a bunch of huge concrete beams buried in the ground.

 

[Shannow]

Yep, pre-stressed concrete taken to the next level...no concrete at all in the lower tensile section

 

[andyd]

I worked in a pre-stressed plant for a while. You really don't want to be around when a cable lets go.