# how does thickness affect the maximum crushing strength and modulus of rupture of wood?

I have modulus of rupture (MOR) and maximum crushing strength of various species of wood. I am trying to understand how the thickness of wood a wood beam laid flat on the ground would affect both modulus of rupture and crushing strength. The practical application is this: We make "crane mats" which are essentially 6 pieces of long timbers bolted together. Each timber is 18 feet by 7.5" x 7.5". The entire mat therefore is 18' x 7.5" x 45". One species we use is eucalyptus grandis, and has a MOR and crushing strength of 118 and 60 MPa respectively. In contrast, red oak has an MOR and crushing strength of 75 and 42 respectively.

If my eucalyptus mat is, for example, 7.5" thick, and it lies flat on the ground, is that equal in MOR or crushing strength to a 12" thick mat of red oak?

I would be very appreciative for any tutoring. I have spent a full day trying to figure this out by myself but I'm not trained as an engineer. Thank you!