Merbau wood properties

[kmead]

I have been tasked with designing a small pedestrian bridge with Merbau wood. I have to admit, I've never heard of this specie of wood and can't seem to find its properties. I have searched extensively but didn't come up with anything useful, so any help as to the design properties of Merbau would be greatly appreciated.

 

[TehMightyEngineer]

From the 2010 Wood Handbook (you can find this online)

Merbau (Malaysia), ipil (Philippines), and kwila (New Guinea) are names applied to species of the genus Intsia, most commonly I. bijuga. Intsia is distributed throughout the Indo–Malaysian region, Indonesia, Philippines, and many western Pacific islands, as well as Australia. Freshly cut yellowish to orange–brown heartwood turns brown or dark red–brown on exposure to air. The texture is rather coarse, and the grain is straight to interlocked or wavy. The strength of air-dried merbau is comparable with that of hickory (Carya), but density is somewhat lower (800 kg m –3 (50 lb ft –3 ) at 12% moisture content). The wood dries well with little degrade but stains black in the presence of iron and moisture. Merbau is rather difficult to saw because it sticks to saw teeth and dulls cutting edges. However, the wood dresses smoothly in most operations and finishes well. Merbau has good durability and high resistance to termite attack. The heartwood resists treatment, but the sapwood can be treated with preservatives. Merbau is used in furniture, fine joinery, turnery, cabinets, flooring, musical instruments, and specialty items.

Looks like you're going to have difficulty getting any sort of graded lumber or NDS style strength data on it. I'd probably just design it like hickory as they stated and be conservative in the design.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[dik]

The texture is rather coarse, and the grain is straight to interlocked or wavy.

Often with interlocking or wavy grain, there could be a lot of 'reaction' wood... as noted with sawing, this may make it a little more difficult to work with.

Merbau is used in furniture, fine joinery, turnery, cabinets, flooring, musical instruments, and specialty items.

If this is the case, then it may be that the material has to be carefully selected.

Dik

 

[boo1]

See FLP link

https://www.fpl.fs.fed.us/documnts/...an_Oceanic/htmlDocs_SEAsian/Intsiabijuga.html

 

[kmead]

Thank you all for the helpful information

 

[hokie66]

What parts of the bridge are intended to be constructed of Merbau? We use a lot of Merbau in Australia for decking boards, but not for structural members.

 

[kmead]

hokie66,
The decking and railing will be Merbau and the beams will be glulaminated timber.

 

[hokie66]

Decking and railings are a good uses of Merbau. I don't know why, as TME's reference says they are the same thing, but when we use the material for decking, we call it Merbau, but for railings, we call it Kwila. I always thought they were different timbers, but maybe not. But both are considered excellent for exposed use. More expensive than say treated pine, but last much longer. For the decking, use stainless nails or screws. For the railings, either stainless or galvanized bolts. Would be interested to see the railing details.

 

[BAretired]

Never heard of it before, but some properties are listed here:

http://www.wood-database.com/merbau/

and here is a video which may be of interest:

http://www.eastteak.com/exotic-woods/merbau-lumber/

BA

 

[Toby43]

As Hokie66 said, here in Australia it is used extensively for decking due to its good durability in exposed environments. You can also get Glulaminated beams of Merbau, which here in Australia get certification/rating from the "Glued Laminated Timber Association of Australia" or GLTAA. This rating is typically GL10, GL13... GL17 etc... which properties from AS1720.1 apply. Not sure if other parts of the world have similar rating systems. Available sizes here, would not however be large enough to accommodate decent bridge spans. Another thing to watch with Merbau, is its tendency to "bleed" after wetting. It can make an absolute mess of anything it is attached to.