Earthquake resistance: Linear, or not...? - Page 5

>
>
> Kris Krieger wrote:
>
>>>>>
>>>>I know the Richter scale is exponential, but I'm still wondering
>>>>whether a structure builkt to withstand X.Y fails at X.Y+1. So, they
>>>>aer currently retrofitting the Golden Gate Bridge to withstand
>>>>soemthng like 8.3, but does that mean it will fail (i.e.
>>>>disintegrate) at 8.4, or what?
>>>>
>>>Can't be done, except in a computer model, cause there's too many
>>>variables. First, you have to define *failure* then design around that
>>>parameter. In SW FL for example the homes I design are supposed to
>>>sustain a 130 to 150 mph wind and usually they do.
>>>But that doesn't mean things won't fail.
>>>
>>SO, if it's designed to withstand 150mph, and a 160mph wind occurs, the
>>whole thing simply disintegrates instantly...?
>>What I'm trying to figure is, if people are in a bldg (house, highrise,
>>whatever) rates to withstand X.Y, but a quake of X.y+1 occurs, does the
>>bldg just completely disintegrate/implode into shards at that point and
>>kill everyone inside?
>>
>
> The answer is that the failure is not necessarily so. Building do not
> normally implode without controlled explosions. the design itself can
> mitigate against specific failures as you suggest with your wind
> example

> below. One resource, partially paid for with your taxes:
> http://www.bssconline.org/

>
>>
>>>On my own house, it went through several hurricanes but some things
>>>did fail, though nothing structural.
>>>If any of those hurricanes would have stalled on my house there very
>>>well may have been structural failure.
>>>Some of the soffit tore loose, a design flaw (which was later
>>>corrected), that allowed wind to penetrate the envelope.
>>>If this wind would have sustained it may have lifted that portion of
>>>the roof and once that happens its all over.
>>>(I installed more, and longer, nails along the edge of the fascia that
>>>attaches the soffit and used 24 tubes of silicone caulk to secure the
>>>soffit to the stucco wall and fascia. This had the added benefit of
>>>thwarting the yellow jackets from nesting in the valleys of the
>>>soffit) Regarding the Golden Gate, what did they do, put it on pulleys
>>>so it'll sway like a pendelum?
>>>
>>I couldn't really teel from the program - in many areas, it looks like
>>they're reinforcing it, but I don't knw whether other areas might be

>>onto rubber "floats" - I couldn't tell. But San Francisco (IIRC) has
>>been literally lifted and placed onto rubber plugs that are supposed to
>>absorb the shaking. THey also described the swaying that some wooden
>>houses can withstand.
>>So that's what all got me wondering about building for earthquake
>>resistance, and what the limits of that are.
>>I'm not sure I asked the question properly, either.
>>
>
> happy reading. in the links below:
>
> http://www.bssconline.org/links.html
>
> For your own hazards related calculations there are several FEMA tools
> and you can even get free training in them.
>

>
>>
>>>> Kris Krieger wrote:
>>>>> I was watching something about earthquakes and building (or
>>>>> retrofitting) for earthquake resistance. I'm assuming it's a
>>>>> "curved graph", but maybe not? So I was wondering, if something is
>>>>> made to survive an earquake of X.Y , would it fail catstrophically
>>>>> at X.Y+1, or would damage increased in a way that'd be mroe of a
>>>>> cruved line of a graph...? I'd assuem teh latter, but what seems
>>>>> logical, isn't always how things work.
>>>> It doesn't work like that. The interactions involved are more
>>>> complicated that the question assumes. FYI, the Richter scale is
>>>> exponential:
>>>> http://en.wikipedia.org/wiki/Richter_scale
>>> I know the Richter scale is exponential, but I'm still wondering
>>> whether a structure builkt to withstand X.Y fails at X.Y+1. So, they
>>> aer currently retrofitting the Golden Gate Bridge to withstand
>>> soemthng like 8.3, but does that mean it will fail (i.e.
>>> disintegrate) at 8.4, or what?
>>
>> Can't be done, except in a computer model, cause there's too many
>> variables. First, you have to define *failure* then design around that
>> parameter. In SW FL for example the homes I design are supposed to
>> sustain a 130 to 150 mph wind and usually they do.
>> But that doesn't mean things won't fail.
>
> SO, if it's designed to withstand 150mph, and a 160mph wind occurs, the
> whole thing simply disintegrates instantly...?
>
> What I'm trying to figure is, if people are in a bldg (house, highrise,
> whatever) rates to withstand X.Y, but a quake of X.y+1 occurs, does the
> bldg just completely disintegrate/implode into shards at that point and
> kill everyone inside?
>
>
>> On my own house, it went through several hurricanes but some things
>> did fail, though nothing structural.
>> If any of those hurricanes would have stalled on my house there very
>> well may have been structural failure.
>> Some of the soffit tore loose, a design flaw (which was later
>> corrected), that allowed wind to penetrate the envelope.
>> If this wind would have sustained it may have lifted that portion of
>> the roof and once that happens its all over.
>> (I installed more, and longer, nails along the edge of the fascia that
>> attaches the soffit and used 24 tubes of silicone caulk to secure the
>> soffit to the stucco wall and fascia. This had the added benefit of
>> thwarting the yellow jackets from nesting in the valleys of the
>> soffit) Regarding the Golden Gate, what did they do, put it on pulleys
>> so it'll sway like a pendelum?
>
> I couldn't really teel from the program - in many areas, it looks like
> they're reinforcing it, but I don't knw whether other areas might be put
> onto rubber "floats" - I couldn't tell. But San Francisco (IIRC) has
> been literally lifted and placed onto rubber plugs that are supposed to
> absorb the shaking. THey also described the swaying that some wooden
> houses can withstand.

>>>>> Kris Krieger wrote:
>>>>>> I was watching something about earthquakes and building (or
>>>>>> retrofitting) for earthquake resistance. I'm assuming it's a
>>>>>> "curved graph", but maybe not? So I was wondering, if something
>>>>>> is made to survive an earquake of X.Y , would it fail
>>>>>> catstrophically at X.Y+1, or would damage increased in a way
>>>>>> that'd be mroe of a cruved line of a graph...? I'd assuem teh
>>>>>> latter, but what seems logical, isn't always how things work.
>>>>> It doesn't work like that. The interactions involved are more
>>>>> complicated that the question assumes. FYI, the Richter scale is
>>>>> exponential:
>>>>> http://en.wikipedia.org/wiki/Richter_scale
>>>> I know the Richter scale is exponential, but I'm still wondering
>>>> whether a structure builkt to withstand X.Y fails at X.Y+1. So,
>>>> they aer currently retrofitting the Golden Gate Bridge to withstand
>>>> soemthng like 8.3, but does that mean it will fail (i.e.
>>>> disintegrate) at 8.4, or what?
>>> Can't be done, except in a computer model, cause there's too many
>>> variables. First, you have to define *failure* then design around
>>> that parameter. In SW FL for example the homes I design are
>>> supposed to sustain a 130 to 150 mph wind and usually they do.
>>> But that doesn't mean things won't fail.
>> SO, if it's designed to withstand 150mph, and a 160mph wind occurs,
>> the whole thing simply disintegrates instantly...?
>> What I'm trying to figure is, if people are in a bldg (house,
>> highrise, whatever) rates to withstand X.Y, but a quake of X.y+1
>> occurs, does the bldg just completely disintegrate/implode into
>> shards at that point and kill everyone inside?
>>> On my own house, it went through several hurricanes but some things
>>> did fail, though nothing structural.
>>> If any of those hurricanes would have stalled on my house there very
>>> well may have been structural failure.
>>> Some of the soffit tore loose, a design flaw (which was later
>>> corrected), that allowed wind to penetrate the envelope.
>>> If this wind would have sustained it may have lifted that portion of
>>> the roof and once that happens its all over.
>>> (I installed more, and longer, nails along the edge of the fascia
>>> that attaches the soffit and used 24 tubes of silicone caulk to
>>> secure the soffit to the stucco wall and fascia. This had the added
>>> benefit of thwarting the yellow jackets from nesting in the valleys
>>> of the soffit) Regarding the Golden Gate, what did they do, put it
>>> on pulleys so it'll sway like a pendelum?
>> I couldn't really teel from the program - in many areas, it looks
>> like they're reinforcing it, but I don't knw whether other areas
>> might be put onto rubber "floats" - I couldn't tell. But San
>> Francisco (IIRC) has been literally lifted and placed onto rubber
>> plugs that are supposed to absorb the shaking. THey also described
>> the swaying that some wooden houses can withstand.
> Earth tremours are usually cyclic, so anything like rubber plugs will
> certainly help. I've experienced a Richter 7.8 in PNG, and seen what
> happens to structures in similar shakes. In timber structures,
> multi-bolted plates are preferable to single bolts, also trussed
> structures work well. In PNG joints in traditional buildings are
> constructed out of a complex weave of bush vine; acts as a torsion
> joint - moves, but tightens as it moves.
> Much depends on the land form and geotechnics. Gravelly, sandy soils
> absorb the shock waves well, but there may be landslides. Soldered
> copper pipes more likely to burst that threaded compression joints. A
> 7.8 in Mexico City will cause far more destruction because its all
> clay in a bowl of rock - wobbles like a jelly. I guess the problem in
> SF would be shear. The whole west side is slowly on its way to Hawaii

> Troppo wrote:
>>>>>> Kris Krieger wrote:
>>>>>>> I was watching something about earthquakes and building (or
>>>>>>> retrofitting) for earthquake resistance. I'm assuming it's a
>>>>>>> "curved graph", but maybe not? So I was wondering, if something
>>>>>>> is made to survive an earquake of X.Y , would it fail
>>>>>>> catstrophically at X.Y+1, or would damage increased in a way
>>>>>>> that'd be mroe of a cruved line of a graph...? I'd assuem teh
>>>>>>> latter, but what seems logical, isn't always how things work.
>>>>>> It doesn't work like that. The interactions involved are more
>>>>>> complicated that the question assumes. FYI, the Richter scale is
>>>>>> exponential:
>>>>>> http://en.wikipedia.org/wiki/Richter_scale
>>>>> I know the Richter scale is exponential, but I'm still wondering
>>>>> whether a structure builkt to withstand X.Y fails at X.Y+1. So,
>>>>> they aer currently retrofitting the Golden Gate Bridge to withstand
>>>>> soemthng like 8.3, but does that mean it will fail (i.e.
>>>>> disintegrate) at 8.4, or what?
>>>> Can't be done, except in a computer model, cause there's too many
>>>> variables. First, you have to define *failure* then design around
>>>> that parameter. In SW FL for example the homes I design are
>>>> supposed to sustain a 130 to 150 mph wind and usually they do.
>>>> But that doesn't mean things won't fail.
>>> SO, if it's designed to withstand 150mph, and a 160mph wind occurs,
>>> the whole thing simply disintegrates instantly...?
>>> What I'm trying to figure is, if people are in a bldg (house,
>>> highrise, whatever) rates to withstand X.Y, but a quake of X.y+1
>>> occurs, does the bldg just completely disintegrate/implode into
>>> shards at that point and kill everyone inside?
>>>> On my own house, it went through several hurricanes but some things
>>>> did fail, though nothing structural.
>>>> If any of those hurricanes would have stalled on my house there very
>>>> well may have been structural failure.
>>>> Some of the soffit tore loose, a design flaw (which was later
>>>> corrected), that allowed wind to penetrate the envelope.
>>>> If this wind would have sustained it may have lifted that portion of
>>>> the roof and once that happens its all over.
>>>> (I installed more, and longer, nails along the edge of the fascia
>>>> that attaches the soffit and used 24 tubes of silicone caulk to
>>>> secure the soffit to the stucco wall and fascia. This had the added
>>>> benefit of thwarting the yellow jackets from nesting in the valleys
>>>> of the soffit) Regarding the Golden Gate, what did they do, put it
>>>> on pulleys so it'll sway like a pendelum?
>>> I couldn't really teel from the program - in many areas, it looks
>>> like they're reinforcing it, but I don't knw whether other areas
>>> might be put onto rubber "floats" - I couldn't tell. But San
>>> Francisco (IIRC) has been literally lifted and placed onto rubber
>>> plugs that are supposed to absorb the shaking. THey also described
>>> the swaying that some wooden houses can withstand.
>> Earth tremours are usually cyclic, so anything like rubber plugs will
>> certainly help. I've experienced a Richter 7.8 in PNG, and seen what
>> happens to structures in similar shakes. In timber structures,
>> multi-bolted plates are preferable to single bolts, also trussed
>> structures work well. In PNG joints in traditional buildings are
>> constructed out of a complex weave of bush vine; acts as a torsion
>> joint - moves, but tightens as it moves.
>> Much depends on the land form and geotechnics. Gravelly, sandy soils
>> absorb the shock waves well, but there may be landslides. Soldered
>> copper pipes more likely to burst that threaded compression joints. A
>> 7.8 in Mexico City will cause far more destruction because its all
>> clay in a bowl of rock - wobbles like a jelly. I guess the problem in
>> SF would be shear. The whole west side is slowly on its way to Hawaii
>
> I thought it was headed *under* the east side, and slightly south....
>

>

>>
>>> On my own house, it went through several hurricanes but some things
>>> did fail, though nothing structural.
>>> If any of those hurricanes would have stalled on my house there very
>>> well may have been structural failure.
>>> Some of the soffit tore loose, a design flaw (which was later
>>> corrected), that allowed wind to penetrate the envelope.
>>> If this wind would have sustained it may have lifted that portion of
>>> the roof and once that happens its all over.
>>> (I installed more, and longer, nails along the edge of the fascia
>>> that attaches the soffit and used 24 tubes of silicone caulk to
>>> secure the soffit to the stucco wall and fascia. This had the added
>>> benefit of thwarting the yellow jackets from nesting in the valleys
>>> of the soffit) Regarding the Golden Gate, what did they do, put it
>>> on pulleys so it'll sway like a pendelum?
>>
>> I couldn't really tell from the program - in many areas, it looks
>> like they're reinforcing it, but I don't knw whether other areas
>> might be put onto rubber "floats" - I couldn't tell. But San
>> Francisco (IIRC) has been literally lifted and placed onto rubber
>> plugs that are supposed to absorb the shaking. THey also described
>> the swaying that some wooden houses can withstand.
>
> Earth tremours are usually cyclic, so anything like rubber plugs will
> certainly help. I've experienced a Richter 7.8 in PNG, and seen what
> happens to structures in similar shakes. In timber structures,
> multi-bolted plates are preferable to single bolts, also trussed
> structures work well. In PNG joints in traditional buildings are
> constructed out of a complex weave of bush vine; acts as a torsion
> joint - moves, but tightens as it moves.

>
> Much depends on the land form and geotechnics. Gravelly, sandy soils
> absorb the shock waves well, but there may be landslides. Soldered
> copper pipes more likely to burst that threaded compression joints. A
> 7.8 in Mexico City will cause far more destruction because its all
> clay in a bowl of rock - wobbles like a jelly. I guess the problem in
> SF would be shear.

liqufaction <?sp?>
> The whole west side is slowly on its way to Hawaii
> ...