Timber Bridge Lateral Bracing
Timber Bridge Lateral Bracing
(OP)
Hi,
I have a short timber bridge which is 10'0" long x 8'-0" wide. The architect wants a concrete abutment at one end and diagonal braces from the bottom of the concrete abutment to support the other end of the bridge. We would like to keep the bridge independent from the existing structure.
I am concerned about the lateral stability of the bridge since in effect I have a cantilevered diaphragm. Are there any limitations to this? And what rule of thumb would you use to calculate the lateral load since it is pretty much an open light bridge.
Thanks
I have a short timber bridge which is 10'0" long x 8'-0" wide. The architect wants a concrete abutment at one end and diagonal braces from the bottom of the concrete abutment to support the other end of the bridge. We would like to keep the bridge independent from the existing structure.
I am concerned about the lateral stability of the bridge since in effect I have a cantilevered diaphragm. Are there any limitations to this? And what rule of thumb would you use to calculate the lateral load since it is pretty much an open light bridge.
Thanks






RE: Timber Bridge Lateral Bracing
RE: Timber Bridge Lateral Bracing
RE: Timber Bridge Lateral Bracing
Any comments?
RE: Timber Bridge Lateral Bracing
RE: Timber Bridge Lateral Bracing
It could be designed as a diaphragm, but you would need to go through the same design requirements as per a shear wall. After including the restraint needed for wind loads on the beams, it's probably easiest to follow bridgebusters suggestions.
RE: Timber Bridge Lateral Bracing
Why can't I use 1x6 T&G planks as a diaphragm. What's the difference between that at plywood other than the spacing of the joints (ie every four or 8 feet for plywood and every 6" for the decking)
For the load to transfer across the joints I've always looked at it as the load getting into the nails, then the rafters, back through the nails across the joint and then back into the diaphragm.
Am I missing something
RE: Timber Bridge Lateral Bracing
Why can't I use 1x6 T&G planks as a diaphragm. What's the difference between that at plywood other than the spacing of the joints (ie every four or 8 feet for plywood and every 6" for the decking)
For the load to transfer across the joints I've always looked at it as the load getting into the nails, then the rafters, back through the nails across the joint and then back into the diaphragm.
Am I missing something?
RE: Timber Bridge Lateral Bracing
Any significant lateral loads on the bridge could fail the connections (likely pullout of the nails). This is the reason most areas have banned the use of shiplap sheathing in shear walls and require OSB, plywood, etc. instead. Even if it does not fail the connections, you will likely have large lateral deflections.