Just back from Madeira, and this bridge that took my fancy in Sao Vicente.
I'm not convinced, the bolts go through the width of the planks, this makes them vey weak. There must be something strong holding the laminations together, if there isn't, I am not using that bridge.
Looking at that fist pic it appears as if the bolts are between the timbers ...as if grooves have been created to take the bolts or a hole drilled where the faces meet .
Seen similar construction technique used for buildings in this country. IIRC several motorway services stations have roofs supported on large beams of this "laminate".
With machine finished surfaces and modern glues I'd put money on the grain giving before the joints do.
Looking at , they claim the same strength from a 550mmx135mm laminated softwood beam as for a 305x165mm steel I-beam. If you imagine that bridge made from I-beams, the wooden one actually looks like it might be overengineered...
Dear Reentrant There may not be any glue evident but there are certainly signs of it. Something is holding the lamina together and as it has all the appearance of a Glulam beam it is probably a phenol resorcinol glue applied in the factory. All the bolts and metallic fixings are doing is holding the laminated members in the right places! It is a pretty standard engineering system
Chris George
PS you have to go to Japan and China (or some UK TF structures) to see non-glued engineered frames. I would have preferred it to have had some precambering aesthetically!
and is sure
I bought a solid oak table last year constructed from a similar material it is showing no signs an early death.
The adhesive is likely a modern casein or phenolic resin not glue (made from cow's hooves or fish bones).
The bridge looks eve perhaps a little over the top for just foot traffic, but this is probably to allow for possible future timber decay. It probably needs are fairly dry climate, or at one where damp conditions are temporary rather than prolonged.
It's hard to imagine what the failure mode of this structure would be. I'm guessing it would some sort of stability failure with both top beams deflecting sideways relative to the deck beams.
It might also be a bridleway. It also has quite a long span, which explains the use of the strong "subdivided Warren Truss" design.
It would more likely be washed off its bearings in a flash flood ...
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