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Re: TROPICAL HARDWOODS

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At 17:28 29/09/97 -0800, you wrote:
>
>I am looking for the shear strength of "ipe", a Brazilian tropical hardwood 
>for use in a boardwalk.  Yes, it is spelled IPE.  Other common names for it 
>include Amapa (Mexico) & Lapacho negro (Argentina).
>
>Some good news and bad news.  The bad news is the boardwalk needs to allow 
>for a 70,000 pound fire truck to cross (16,000 pound wheel load).   The good 
>news is the boardwalk planks bear on sleepers which bear on a grout bed 
>which bear on a structured concrete floor, so if a plank fails, the truck 
>won't fall too far!
>
>I have found the following values for ipe (ultimate values I think).
>
>     Bending strength 22,000 to 28,000 psi  (depending on moisture content)
>
>     Modulus of elasticity  2,920,000 to 3,350,000 psi
>
>     Maximum crushing strength  10,350 to 14,000 psi
>
>Any thoughts on factors of safety to apply to the above values for use in 
>allowable stress design?  Or if LRFD (yikes!), any thoughts on capacity 
>reduction factors (phi) combined with load factors?
>
>Also I could not find a shear strength.  (Something equivalent to 95 psi for 
>Douglas Fir Larch).  Has anyone worked with ipe before?   I thought about 
>proportioning the shear strength up based on the ratio of modulus of 
>elasticity to get a ballpark estimate.
>
>Steve Uthoff, S.E.
>

                            specific mass   shear paralel to the fibers
                              15% humity       strenght limit
                                 g/cm^3          kgf/cm^2         
          
IPE ROXO or IPE PRETO             1.21             145
(tecoma irpetiginosa)

IPE TABACO or IPE AMARELO         1.03             189
(tecoma eximia)

IPE PEROBA                        0.72             121 
(paralelocoma peroba)


Glauco de Deus Ribeiro
Structural Engineer