Steel bridge

[farmerjo]

Hi,

Anyone who can help me with load bearing on C channel (150x75x10)

I'm building a steel bridge across a creek,3 metre span.

It needs to be able to take a 5 ton tractor(wheel base length 2300mm)but various width(narrower) vehicles will also use it.

So the plan was 2 x C channels 2200mm width apart(tractor width 2100mm) and another in the centre of the 2 making 3 main beams with 50x50x3 angle across them

at say 250mm apart.

So my questions are before i proceed,which way will the C channel be strongest.On its side or the 150mm flat side on top.

And will this design be adequate.

Thanks.

 

[VocalNeal]

Generally a beam will be stronger across the wider section so they should be mounted on their side.

 

Surface prep and good painting will stop you disappearing into the void in ten year's time when you have forgotten when you built it.

[canuckamuck]

2 C channel back to back make a kind of I-beam, so stronger, but I cant imagine using them for a 5 ton tractor. You woud be much better off with real I-beams

Also flat spans are weak. Any sort of an arch design underneath will help greatly.

[VocalNeal]

Food for thought if you already have the material? 

 

 

In this picture 3m is only the centre section

 

Something else i found. Also food for thought.

 

[bankruatsteve]

3m?  Why not just throw down a culvert or two and fill it in?

[wayned]

The C section with the 75mm on the top will give the least amount of vertical deflection under load and twist should not be an issue with the 50x50x3 tracks welded every 250mm .  With the material being 10mm thick It should work either way but stronger if mounted with the long side in the vertical.

[farmerjo]

1 hour ago, bankruatsteve said:

3m?  Why not just throw down a culvert or two and fill it in?

I have the steel,can fabricate in my workshop then drag to position.

When it flows at its peak the area is right now for water holding capacity with a bridge(old wood one now) above.

 

[farmerjo]

15 minutes ago, wayned said:

The C section with the 75mm on the top will give the least amount of vertical deflection under load and twist should not be an issue with the 50x50x3 tracks welded every 250mm .  With the material being 10mm thick It should work either way but stronger if mounted with the long side in the vertical.

Ok will make with the main beams on their side.

Even though tractor is nearly 5 ton the highest load i guess would be the rear wheel weight at 1.5 metres which maybe 3 ton.

[eyecatcher]

to be clear the 150mm height is your strongest position.

 

another idea would be to set up 4 channels with 2 in the middle back to back.

inside the flanges you can set up a few concrete planks at 50mm depth as permanent shutters and then you can mix insitu concrete to fill up the remainder 100mm.

what you have then is a very strong steel and concrete structure.

 

4 channels and half a dozen concrete planks cut in half