Laminated hardwood beams

[phuduhudu]

We are proposing using laminated saligna (species of eucalyptus) beams for a heptagonal (5 sides) hall roof. They will meet at the apex and be about 9.5m long from eaves to apex. For aesthetic reasons we want them also to taper slightly in depth towards the eaves. There will be an eaves tie to restrain them so they will develop moment and compressive force. Does anyone have experience of this type of structure and the things to look out for with design? I am particularly concerned about the connections and how to transfer some quite large forces through them. (e.g. 50kN eaves tie force). I am working in Botswana so any experience in the area will be helpful.

Carl Bauer

http://www.bauerconsultbotswana.com

 

[pba]

I have no experience in using eucaliptus. Based on your spans, you will be looking at some large timbers. Can these be brought inside the ring beam so that the load is applied as direct compression?

At apex the same thing occurs, with five members meeting at a point. The connection needs to be big enough to give space for the connection fittings.

Surely a five sided roof is Pentagonal? and an eight sided roof Heptagonal?

It strikes me that the proposed taper is the wrong way round (speaking structurallly). More load would be applied toward the outside due the the greater purlin spans and the maximum bending moment would also be closer the the outside support so that is where the 'meat' of the section should be.