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From: tsuchiya@xxxxxxxxxxxxxx (N John Tsuchiya)
Newsgroups: alt.architecture
Subject: Re: A good book.
Date: 17 Sep 1993 04:22:34 GMT
Organization: Massachusetts Institute of Technology
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John Porter in a previous article was questioning the statement I made
earlier about a tensile structure being "weakened" by increasing the
tensile strength of its members. And actually, he was absolutely right on
all points. The original statement was sort of a "trick" statement, which
depends on the fact that for most materials, increasing the tensile strength
increases the modulus of elasticity (Young's Modulus). And, as John Porter
correctly pointed out, this would reduce the material's ability to distribute
out stresses. For large structures (as the original statement indicated),
this will tend to be a large factor in the strength of the structure, since
the stresses are already so high (i.e., causing the critical Griffith's
length to be dangerously small). Furthermore, for most structures, the
ultimate tensile strength (or compressive strength as well) is never
even approached, so increasing it adds nothing to the overall strength of
the structure.
Well, that was the trick behind the "magic"...
John Tsuchiya
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From: tsuchiya@xxxxxxxxxxxxxx (N John Tsuchiya)
Newsgroups: alt.architecture
Subject: Re: A good book.
Date: 17 Sep 1993 04:22:34 GMT
Organization: Massachusetts Institute of Technology
Lines: 20
Distribution: world
Message-ID: <27be2a$n8@xxxxxxxxxxxxxxxxxxxxxxxxx>
References: <26u6g7$pnu@xxxxxxxxxxxxxxxxxxxxxxxxx> <27al1l$jh9@xxxxxxxxxxx>
NNTP-Posting-Host: m66-080-22.mit.edu
John Porter in a previous article was questioning the statement I made
earlier about a tensile structure being "weakened" by increasing the
tensile strength of its members. And actually, he was absolutely right on
all points. The original statement was sort of a "trick" statement, which
depends on the fact that for most materials, increasing the tensile strength
increases the modulus of elasticity (Young's Modulus). And, as John Porter
correctly pointed out, this would reduce the material's ability to distribute
out stresses. For large structures (as the original statement indicated),
this will tend to be a large factor in the strength of the structure, since
the stresses are already so high (i.e., causing the critical Griffith's
length to be dangerously small). Furthermore, for most structures, the
ultimate tensile strength (or compressive strength as well) is never
even approached, so increasing it adds nothing to the overall strength of
the structure.
Well, that was the trick behind the "magic"...
John Tsuchiya