flitch plate design

[lookattheplans]

i have a psl beam spaning approx. 21 feet. the beam is 7 inch wide and 14 inch deep supporting a 2x4 wall and roof above. the wall is not centered on the beam. need to add a 1/2 inch x 14 inch flitch plate. how do i determine the number and spacing of bolts required?

 

[tonyuk]

The approach we adopt is to assume that across the span the bolts are transferring the calculated load proportion from the timber to the plate, and at the bearings the load carried by the plate is transferred back to the timber. Standard UK practice is to make the plate slightly less deep than the timber to allow for timber shrinkage, thus the load is initially applied to the timber and the bearing is on the timber only. Once you have worked out an optimum bolt size, probably determined by the bearing of bolt on timber, you can work out the required spacing, though this should not be too large - we suggest 600mm (2'). At the bearings you need to ensure there is enough room for the required number of bolts.

http://www.sda.co.uk/info/sbw/flitch.htm

gives more

TonyB SDA UK

 

[lookattheplans]

o.k. i understand what you saying however maybe i should have been more specific. i'm looking for an equation or design example. if i want the wood and steel plate to act as a single memeber what equations/theory do i need to apply to calculate the size and spacing of bolts. i have a uniform load across the length. from mechanics do i just us my shear flow equations and used transformed areas to calculate this or is there a better approach.

 

[SlideRuleEra]

See pages 5 and 6 of "Design Guides for Flitch Plate Beams & Lally Columns" at this link (free .pdf download)

http://www.destefanoassociates.com/tech/flitch.pdf

http://www.SlideRuleEra.net

 

[connect2]

great handle! 'lookattheplans', love it. transfer the shear. ok thats it for me. 3 beers, no lunch and i'm outta here.