On 29-Apr-2005, "J. Clarke" wrote:

Concrete for example
doesn't flex noticeably before it breaks so by your reasoning concrete
should never be used as a building material.

Concrete is a perfect example of the problem and one where overdesign is
a problem. Too much steel reinforcement in a small beam compared to less
steel in a deeper beam - the lightly reinforced beam will fail slowly with
the ductile steel failing in tension. The overbuilt beam with too much
steel will fail suddenly and in a brittle manner by failure of the concrete
in compression.

When dealing with wooden beams, making the beam stronger than called for is
not going to result in sudden failure with no warning unless the original
design would also fail suddenly with no warning at a lighter load.

The lighter beam would bend considerably before failure. The heavy beam
can carry a significant overload and can cause it's supports to fail without
warning. You can't look at a building by considering its components individually.
You have to look at the entire structure as a system.

I would like you to quote the statute which makes it a criminal offense to
build something stronger than is required.

If an engineer or architect is responsible for the design of a building,
they are required to ensure that it does not fail in a manner that does not
give warning (i.e it must fail in a ductile manner). If the design of one
component results in an unexpected failure, whether from over- or underdesign,
this results in professional liability. Maybe not the Code of Hammurabi, but
there are still legal consequences - such as criminal negligence causing death.

Mike

"Michael Daly" wrote in message
...
On 29-Apr-2005, "J. Clarke" wrote:

Concrete for example
doesn't flex noticeably before it breaks so by your reasoning concrete
should never be used as a building material.

Concrete is a perfect example of the problem and one where overdesign is
a problem. Too much steel reinforcement in a small beam compared to less
steel in a deeper beam - the lightly reinforced beam will fail slowly with
the ductile steel failing in tension. The overbuilt beam with too much
steel will fail suddenly and in a brittle manner by failure of the
concrete
in compression.

This is the classic case, but it is NOT a case of overdesign. It is a case
of WRONG design. Overdesign would be sizing the beam twice as deep as it
needs to be, not providing a faulty design.

When dealing with wooden beams, making the beam stronger than called for
is
not going to result in sudden failure with no warning unless the
original
design would also fail suddenly with no warning at a lighter load.

The lighter beam would bend considerably before failure.

But, we are considering overdesign. In this case we must assume that the
design with the lighter beam is SUFFICIENT to carry the load. It is not
expected to fail. Thus a heavier beam would be sufficient as well.

The heavy beam
can carry a significant overload and can cause it's supports to fail
without
warning.

Wouldn't the supports be overdesigned as well? You seem to be considering
loads that cause buildings to fail. In my mind these are things like
earthquake, wind and perhaps snow. With an earthquake if the supports are
going to fail under the load it doesn't matter if the beam is oversized or
not. You are crushed. Likewise with wind. Snow is a different story as it
accumulates slowly, and there you might have a point. But even then I
contend that while an engineering system tries to be balanced, in practice
there is enough variation in materials and fabrication that it is impossible
to be 100% certain how it will fail.

You can't look at a building by considering its components individually.
You have to look at the entire structure as a system.

Sure, and what if the overdesigner does this and overbuilds everything?

I would like you to quote the statute which makes it a criminal offense
to
build something stronger than is required.

If an engineer or architect is responsible for the design of a building,
they are required to ensure that it does not fail in a manner that does
not
give warning (i.e it must fail in a ductile manner). If the design of one
component results in an unexpected failure, whether from over- or
underdesign,
this results in professional liability. Maybe not the Code of Hammurabi,
but
there are still legal consequences - such as criminal negligence causing
death.

Mike

Perhaps you can quote the regulation that states this?
Also, give us a case or two where overdesign has resulted in criminal
negligence causing death.
If they exist you should be able to cite one or two examples.

-Jack

On 29-Apr-2005, "J" wrote:

This is the classic case, but it is NOT a case of overdesign.

Over design version "just throw some more rebar in there - it's
never bad to overdesign".

But, we are considering overdesign. In this case we must assume that the
design with the lighter beam is SUFFICIENT to carry the load. It is not
expected to fail. Thus a heavier beam would be sufficient as well

For the design load - yes. For the actual load - no. See my other post.
The issue is whether you get warning of impending failure. Overdesign
can result in brittle failure without warning.

Wouldn't the supports be overdesigned as well?

The case from which this derived is one where someone is considering
a single element, not designing the whole building. If someone in
a forum like this who is not an engineer or architect gets hold of
a ridiculous claim like "overdesign is never bad" all sorts of
unexpected evil can result.

Perhaps you can quote the regulation that states this?

Criminal Code in Canada.

Mike.

Michael Daly wrote:

On 29-Apr-2005, "J" wrote:

This is the classic case, but it is NOT a case of overdesign.

Over design version "just throw some more rebar in there - it's
never bad to overdesign".

But, we are considering overdesign. In this case we must assume that the
design with the lighter beam is SUFFICIENT to carry the load. It is not
expected to fail. Thus a heavier beam would be sufficient as well

For the design load - yes. For the actual load - no. See my other post.
The issue is whether you get warning of impending failure. Overdesign
can result in brittle failure without warning.

Uh, we're talking about _wood_ here. Please explain how substituting a
strong piece of wood for a weak piece of wood is going to result in
"brittle failure without warning".

Wouldn't the supports be overdesigned as well?

The case from which this derived is one where someone is considering
a single element, not designing the whole building. If someone in
a forum like this who is not an engineer or architect gets hold of
a ridiculous claim like "overdesign is never bad" all sorts of
unexpected evil can result.

Perhaps you can quote the regulation that states this?

Criminal Code in Canada.

Yeah? Where does it say that?

Mike.

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On 29-Apr-2005, "J. Clarke" wrote:

Uh, we're talking about _wood_ here.

No we're talking about overdesign.

Criminal Code in Canada.

Yeah? Where does it say that?

Criminal negligence causing death is a punishable offence in
the Canadian Criminal Code. You want an exact quote, contact a lawyer.

Mike

Michael Daly wrote:

On 29-Apr-2005, "J. Clarke" wrote:

Uh, we're talking about _wood_ here.

No we're talking about overdesign.

No, you're trying to take the thread off topic.

Criminal Code in Canada.

Yeah? Where does it say that?

Criminal negligence causing death is a punishable offence in
the Canadian Criminal Code. You want an exact quote, contact a lawyer.

You made the assertion, it's up to you to support it. If you don't want to
support it them don't make the assertion. Now, do you have case law in
which making a part of a structure stronger than required resulted in a
conviction for criminal negligence in Canada or are you just a Chicken
Little wannabee?

Mike

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On 30-Apr-2005, "J. Clarke" wrote:

No, you're trying to take the thread off topic.

Thread topics change. Get over it.

You made the assertion, it's up to you to support it.

I didn't say it has happened, I said it could happen. If the circumstances
arise, all it takes is a zealous crown prosecutor to make the case. Since
the law has been applied in other cases, that's not much of a stretch.

Mike

I have been watching this thread trying to keep out of it but I lost the
struggle .....

Michael Daly wrote:
snip

For the design load - yes. For the actual load - no. See my other post.
The issue is whether you get warning of impending failure. Overdesign
can result in brittle failure without warning.


Wouldn't the supports be overdesigned as well?
I don't recall seeing anything that said that oversizing one component
in a system will/could/might cause a failure at the "design" loads.
Very obviously the entire system does need to be considered _if_ loading
is going beyond the design on any given component.

What I am seeing is a debate that a single (or multiple) over designed
component in a system can cause a failure else where in the system but
losing sight of "designed" and as has been said several times this is
untrue _if_ we are still talking at _designed_ loads.

By the virtue than one constructs a beam capable of carrying double the
designed load by no means ensures that the rest of the system, posts,
footings, etc, are capable of carrying this. But also this same
oversided beam at the _designed_ loads will not cause catastrophic
failure in any other components unless they were themselves either under
designed or inadequately constructed or had a load increase beyond design.

If one constructs a structure like a beam that is, for e.g. capable of
carrying 50% more loading than design but the posts used are still at
designed specs loads, then for sure, if you load the beam to its
increased capacity the posts and other parts are liable to fail.

This is almost an urban legend type of issue. The real item is that all
parts of a structure need to be designed and constructed to meet the
needs and loading requirements. Over sized/designed construction of one
part will not increase the capacity of the system and is where people
become misdirected like some of this discussion. The failure is always
due to trying to load at a level to the specs of the over built piece
rather than the original design. ... and thus results in these
misconceptions that over designed beams, as in the examples in this
thread, cause failures in the posts and where in reality the posts were
never designed or capable of carrying these loads.


The case from which this derived is one where someone is considering
a single element, not designing the whole building. If someone in
a forum like this who is not an engineer or architect gets hold of
a ridiculous claim like "overdesign is never bad" all sorts of
unexpected evil can result.


Perhaps you can quote the regulation that states this?


Criminal Code in Canada.
Sorry this doesn't match in my mind.
Yes, it is criminal to construct an occupancy build that does not
conform to minimal standards stated in various regulations and as result
incur a failure causing 3rd party losses in property, life, well-being,
etc. There is absolutely nothing I have seen that says I can not exceed
any building construction standards and requirements.

Ed

On 29-Apr-2005, Ed & Sue Beresnikow wrote:

There is absolutely nothing I have seen that says I can not exceed
any building construction standards and requirements

But if you do not design a component to conform to standards, but merely
oversize the component, you can cause the structure to behave in a
manner that causes failure. Think especially in terms of statically
indeterminate cases, where load distribution is a function of stiffness.

If you overdesign a component but can show that the overdesign is not
a problem, then there is no risk. Columns in high rise buildings are
an example - you can design several stories to use the same column even
though the upper columns carry a lighter load. However, you have to
_design_ it that way.

Mike

Michael Daly wrote:


On 29-Apr-2005, Ed & Sue Beresnikow
wrote:

There is absolutely nothing I have seen that says I can not exceed
any building construction standards and requirements

But if you do not design a component to conform to standards, but merely
oversize the component, you can cause the structure to behave in a
manner that causes failure. Think especially in terms of statically
indeterminate cases, where load distribution is a function of stiffness.

If you overdesign a component but can show that the overdesign is not
a problem, then there is no risk. Columns in high rise buildings are
an example - you can design several stories to use the same column even
though the upper columns carry a lighter load. However, you have to
_design_ it that way.

So when was the last time a high rise building was constructed from 2x10s?

Mike

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On 30-Apr-2005, "J. Clarke" wrote:

So when was the last time a high rise building was constructed from 2x10s?

You can get drugs to treat your obsessive behavior.

Mike