Review related to structural analisis - earthquake eng & design

[budis]

Dear All CivilEA Members

I create a thread contains my review on some postings, I focus on seismic design / pushover analysis + other topics that I know
I already give several review in following thread :

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I will constantly add my new review at there.
I hope my thread can be a "sticky/permanent thread" so that easily to find & read by all members of CivilEA

I need suggestion from Admin/Protector/Moderator where is the correct forum for my thread & also correct name for my thread.
I feel that my thread in that temporary location ( in Suggestion Forum ) should be moved to an appropriate forum so that easily to find & read by all members of CivilEA.

If that thread moved by Admin/Protector/Moderator to an appropriate/correct forum please give me notification about the new location of it so that I can continue add my review.

I hope my review useful for all of you
Thx

review related to structural analisis - earthquake engineering & design based on ACI318/318M, UBC 1997, IBC & related code

[parhyang]

(a) Just imagine, what if a building located in lowest seismic hazard are & use SMRF ?
(b) Just imagine, what if a building located in highest seismic hazard are & use OMRF ?
Trust me your structure will survive

the building i talk is an old, using codes before capacity design implemented and i think is before intelligence programs such as SAP/TABS familiarly used in our country. most building in the same areas collapse too. u can see in this report i posted,

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i have specific documents from expert EE/SE investigators, but i did not posted in here since language is not in english.

are u have building designed in the same areas and same year periods?

back to my questions,

when using fully ductility for low seismic region, i just have some questions: for what seismicity region maps? and for what complex detailing requirement (unnecessary)

one big reasons using capacity design concepts are economics perspective views, for this reasons why not using elastic design base shear with complex detailing, additional main bars and others requirement for full ductility?







my lecturer master thesis discussed about it, still can not posted in here for language reasons.

[essenza]

the building i talk is an old, using codes before capacity design implemented and i think is before intelligence programs such as SAP/TABS familiarly used in our country. most building in the same areas collapse too

I confused, i think we are not at the same phase. Your statement and paper clearly shows how important confinement is even for lowrise, residential building like one in Yogyakarta even in low seismic area.

are u have building designed in the same areas and same year periods?

I just stated my design experience, I'm not designing any building now.

when using fully ductility for low seismic region, i just have some questions: for what seismicity region maps? and for what complex detailing requirement (unnecessary)

well then will you design 100 story building in zone 1 or 2 using OMF where confinement requirement as in SMF is unnecessary? which one you trust your seismic map (sumatera before and after 2004)?? or your power as engineer to provide ductility?. So once again in this case as i stated before if you provide full ductilily even you are slightly wrong in calculating the magnitude of seismic force, the likeliness of your structure to survive is better than using smaller R than what required from OMF but less confinement, no strong column weak beam etc.

one big reasons using capacity design concepts are economics perspective views, for this reasons why not using elastic design base shear with complex detailing, additional main bars and others requirement for full ductility?

Not good engineering decision if you speak about economics perspective. Why elastic design base shear when you are permitted to reduce the level of seismic force?. So it's contradictive. But i'm okay with IMF R but SMF detailing, or OMF R with IMF detaling this is not unnecessary, it is common practice, at least in my experience.

[parhyang]

Your statement and paper clearly shows how important confinement

not for this reasons i linked, just to show where the building place and how about the others.

which one you trust your seismic map

seismic region maps will always be same, no slightly differences even for next years. differences are only in maximum ground accelerations scale in gravity (RS curve). is this structural or earthquake engineers problems?

well then will you design 100 story building in zone 1 or 2 using OMF where confinement requirement as in SMF is unnecessary?

from which i state, i designed a building with low ductility (OMF) in high seismicity regions (zone 1 or 2)? i just state "complex detailing and additional bars for full ductility requirements are unnecessary in low seismic regions"

Not good engineering decision if you speak about economics perspective.

economic is not always about money, for engineer is means material consumptions. are all engineers neglected? contradictions.

all argument i posted here's for explanations my agreement with budis,

... to use "normal" relation Framing Type & Seismic Zone - Seismic Design Criteria

and try to answering your questions and gave opinions (with citations) to your states,

(a) Just imagine, what if a building located in lowest seismic hazard are & use SMRF ? What's wrong with (a). I always use special moment frame whatever the zone is?

thx

[budis]

I will give my opinion, I try to be fair & objective.

This thread is continuation from :

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My opinion in this thread related with above thread from post#12 until post#17

My post #12
(a) Just imagine, what if a building located in lowest seismic hazard area & use SMRF ?
(b) Just imagine, what if a building located in highest seismic hazard area & use OMRF ?
Simply both extreme examples above are "improper design"

Essenza wrote ( post#13 )
What's wrong with (a)?, of course not (b)

In general case, I'm 100% agree with Parhyang doing such design is inappropriate, or I said in posting#12 as "improper design"
For general/common design such action that is building in lowest seismic design with SMRF --> cause cost inefficiency.

BUT, IN VERY SPECIAL CASE / REASONS, please underline it ( very special reasons ) it could be happen ( Essenza not fully wrong, wrong if used in general design )
JUST EXAMPLE, if in Zone 0 UBC 1997 built tallest building in the world, if the engineers consider blast load ( such as possibility of terrorist attack ) it could be done with SMRF design in lowest seismic Hazard area.
Simply of the idea is adding more reinforcing & detailing to increase ductility
I read such method / technique ( give more reinforcing & detailing to increase ductility ) in many technical paper about blast design.

About posting #15 - #17
Most important thing about Parhyang & Essenza's posting : suggestion to give close attention on seismic detailing, this stuff is very important in seismic design process.

My opinion about Parhyang & Essenza opinion in this thread

About Parhyang post#2 in this thread
For general case, I agree with point of Parhyang answer "one big reasons using capacity design concepts are economics perspective views"
And again as I said above for special reason ( for example blast design ) adding more reinforcing & detailing could be happen, but for general design, economic perspective is important.

Do you both ( Parhyang & Essenza ) still remember director/project manager in consultant firm always/often said :

"I think the dimension ( beam,column, wall ) could be smaller, try !"

For example, general project such as family class apartment tower if the developer think a consultant firm "do inefficient design" of course they will go to other consultant firm that give them lower cost for their tower !
Why ? Because they will sell their apartment units & still there competition from other developer.
Right ?

SUMMARY :
(1) I still in my opinion : I suggest our members to use "normal" relation Framing Type & Seismic Zone - Seismic Design Criteria.
Please underline it ---> it's for general case
(2) I get point from Parhyang's opinion, he agree with me about use "normal" relation Framing Type & Seismic Zone - Seismic Design Criteria
THE SIMPLE REASON IS to reach economic design, read my example above.
(3) I get point from Essenza's opinion, for special case add more reinforcing & detailing could be done.
I give example above about adding more reinforcing & detailing to increase ductility for blast design ( to consider possibility of terrorist attack ).

I hope we ( me, Parhyang & Essenza ) can review new Indonesian Seismic Design Code that will be launched in early of 2011.
Btw, I'm not yet have the draft, plz inform me if there anyone know link for draft of new Indonesian Seismic Design Code ?

I hope our ( me, Parhyang & Essenza ) discussion useful for all of you.
Thx

[essenza]

Budis, your comment is very right actually that's what i want to pointed out that ductility is not related just only to earthquake design, it is properties of structure we can employ to get a robust structure even in low seismic area so why not use it, it provides you margin of safety against possible relatively excessive settlement and overall it provides you eventually stronger structure against possible overloads.

However regarding the economic, i just curious do both of you think that OMF in low seismic area will be more economic than IMF or SMF??I just have impression that it will not in case of semi highrise or highrise building. But perhaps yes if it is lowrise building, but i'm not sure. Do u have document that help you with your statement? because if it is, this is good for my business, at least do OMF with less confinement required from SMF/IMF :P.

Parhyang, u must understand that the seismic map is made from PSHA. U must know that the source of earthquake recorded is scarce, and in just this recent years that more develop and even online technology of recorded earthquake acceleration is available. From the source data, the attenuation relationship and probability model, the earthquake acceleration is "heavily probabilistic". Who will think of more than 7.5 or 8 magnitude will happen before 2004. So the 2002 version from SNI 1726, the 2008 version from SNI 2833 and the latest one the 2010 is in many place is significantly different, thinking that building lifespan is 50 years or more, we don't know what we will face ahead. So my opinion that seismic map is evolved, place that have been considered less risk can be change into medium risk (Singapore for example). Of course it is earthquake engineering problem and not structural problem because guess what?? we have ductility. Pls help me also with other definition of economic besides cost or money? and why do u think material consumption is not money or cost?

Budis i believe you already know that the indonesian code will be similar with asce 7 2010. From some engineers that i know who have been comparing the 2002 version and the new one, Jakarta will not affected very much, hopefully. West of sumatera, south of java and east indonesia is the most affected one. In one seminar they say that seismic map of east part of indonesia is extrapolated due to limited seismic source before 2000, though from geological perspectives shows a possible major earthquake might happen there. If i'm not mistaken, the east part of Indonesia is shifting north. Due to the limited data, they are quite conservative for the east of Indonesia at the moment. One thing they say again that there is a possible unidentified fault line beneath Jakarta if it looks from the map of fault lines. Just hope it will never come true, otherwise God knows :D.

[parhyang]

OMF in low seismic area will be more economic than IMF or SMF??

cost comparison for OMRF to IMRF or IMRF to SMRF will not slightly different, some references says is less than 5% for building with storey greater than 10. not in case of OMRF to SMRF.

the source for additional cost are from,







above are for IMRF to SMRF, required additional point compared to OMRF for minimum main bars reinforcement.

and the latest one the 2010 is in many place is significantly different

for seismicity region maps: of course yes it's a difference, but as i says not slighty comparing to significantly in peak ground acceleration from previous to present and next change in codes. but maps still look similar, only have minor changes, again not in case of PGA.

less risk can be change into medium risk

you says about SNI there's contains 6 class categories, which class, how significantly up? one, two, three, four, or five grades change? when you says less is mean 6 and medium is mean 3 or 4, so grades change up to 3? i'll look back where's.

material consumption is not money or cost

money or cost are relative, not as absolute in material consumption. example is in castellated and prestressed. less material consumptions but required additional cost for construction due to equipment/technology. so when the engineers talk about economics i believe is about efficiencies in less material consumptions, not only about money.

[essenza]

@ Parhyang

Thanks for the info so the additional cost only in stirrups and splicing, however it is just member of the structure beam or column i believe of the same dimension and definitely just comparing formula and spacing requirement, any kid can do that ...hmm not too convincing. It is not telling the whole structure down to the foundation. Surprise me!

I think about seismic map you just seen it as a matter of zone and colors and not looking at the big picture and how really it is obtain. So there's no point to argue with u. And you said minor changes, wow good luck with your design.

Hmm so you try to tell me that an increase of 0.05 g is small, very interesting. I wonder why the need site specific analysis if it just reducing 0.05 g or perhaps 0.1 g from the code:JC_shakehead:

Cost and money is relative, relative to what? did you pay your cost with candy perhaps:dash2:. So can i say that 100 story OMF building will require less material and simple technology than 100 story SMF building?

[parhyang]

any kid can do that

the picture i post taken from papers by a persons with Phd degrees in the University of Mississippi, he's a member of some regions concrete society. why you said he's a kid? i think i did better give opportunities to trust him rather than anonymous like you.

not looking at the big picture and how really it is obtain

the big pictures are in pga/rs, as two times i says before. not seismicity region maps as you says.

you try to tell me that an increase of 0.05 g is small

again from which i state, pga is significant and i give most concern about it not as in seismicity region maps. i usually use judgment for region categories, rounding to one grade highest. using type of MRF in normal selection, low-medium-high to ordinary-intermediate-special. not as you do special for low seismic regions.

material consumption is not money or cost

you ask and i'm done answering.

Cost and money is relative, relative to what? did you pay your cost with candy perhaps

maybe the kids are you, not the doctor i mentions :)

[essenza]

wow that PhD from Misisipi must have work hard comparing those formula or perhaps it is his/her post doc study or you are the Misisipi PhD? yea applause :clap:

yeah yeah PhD rule the world, those who build Pyramid must have PhD degree. Thanks to you i think i will offer my doctorate for free. People like you is an insult to civil engineering community.