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Question

I am working on the repair of a flood damaged house in Townsville. The timber joists supporting the floor of the house have bowed significantly (up to 60mm over 5m span) due to differential foundation motion. Can the joists be re-used, or should they be replaced?

Woodsolutions Answer +

Your question needs some on-site assessment. If the joists are still wet, and still in place, perhaps you can apply weights to straighten them. Timber that dries under load retains its new shape, in this case resuming original straightness. If the joists have been removed from the floor and have dried with a bow it might be possible to re-use them if they are 'crippled' (partially cut). The cut needs to be located centrally over bearers or other supports. Note that the span needs to be checked as crippled joists are classed as simply supported, ie. single span, not continuous. If neither of these strategies are practical the joists may need to be replaced.

Bowed joists
Question

Have you got details of a code or manufacturer's details for Post and Beam construction bracing. The timber framing code has some detailed bracing values for sub floor but not for rest of building. In addition the metal strap systems etc are detailed for stud walls but not post and beam. I see them used extensively for post and beam such as American type barn. Do they need site specific engineering in Australia?

Woodsolutions Answer +

Bracing solutions for stud walls may not be applicable for post and beam construction since the frames in post and beam are generally spaced further apart than the standard 600mm stud spacing. Engineering design is generally required. The Canadian Wood Council has a presentation on post and beam that might be helpful although it refers to Canadian practice. It can be viewed here: https://www.tboake.com/2014/172-Post_Beam_Construct2013.pdf.

Post and beam
Question

Would you be able to help me out designing the following detail? Thanks in advance.
There are a series of 3 LVLs (150x77) next to each other. All of them are cut at an angle (longitudinally) to match the soffit of the element that will be supported by the LVLs.
- Which would be the allowable bearing pressure (compression perpendicular to the fibre)?. This cut means the horizontal fibres will be cut, is that affecting the behaviour of the fibres?
- What would be your suggestion for fixing these 3 LVLs together? Drill a hole and put a long M16 bolt through? This connection is mainly for stability for horizontal loading.
 

Woodsolutions Answer +

It would be best to put this question to the companies that produce LVL (Wesbeam, Carter Holt Harvey, Tilling, etc.) Design properties are likely to vary from one company to another, depending on the composition of their beams. Some companies have a range of LVL products, with different structural properties. All the major producers of engineered timber products have a technical advice line and you will find their details on the net. 

LVL
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