Seismic Options design 1

[pba]

We are at early concept stage for a building in the UK which will require to be designed for seismic conditions.

We currently have a 9m (29.5ft) square structural grid and a regular building shape. I'm giving some thought to flat slab construction, possibly post tensioned.

This is where I hit a dead end as I have limited knowledge of either seismic design or PT. I'd apreciate your comments and/or advice.

For Seismic purposes (as I understand it) the columns need to be strong so that plasticity develops in the floor - For beams I think I understand how this could be achieved but for a flat slab?

Now for lateral bracing, I'm thinking shear walls, and I'm thinking the Architect won't like them! Are there other options?

Clearly, proper design will not be contemplated until we have the appropriate information and skills. Rest assured this is for a reputable client and I work for a reputable consultant!

Thanks in anticipation.

 

[DrADK]

Dear pba,

I do not think that we have in the UK a BS that takes into account seismic loads in the design of concrete members. However, check the related BS-8110, or the EC-8.

May I ask, why do you want to design agains seismic conditions?

It has become appallingly obvious that our technology has exceeded our humanity
- Albert Einstein

 

[pba]

DrADK,

You are correct - BS8110 does not allow for seismic loading and thus cannot be used directly. Advice to date suggests we design to ACI 349, for the seismic condition. This is an American code with which I'm currently unfamiliar! This is feasible but would require separate consideration for Building regulation compliance.

We would have something of an easier time with a steel frame as BS5950 can be used for seismic design with additional recommendations taken from American LRFD code - Indeed we have done so in the past.

Steel frame gives a potentially increased structural zone and limits our options for utilising thermal mass heating/cooling. It has not however been ruled out...

EC-8 is currently being sourced to assess it's validity to this project, but the client recommendation is ASCE 4, which again we will be obtaining.

The requirement to design for seismic is client imposed and reflects the nature and importance of the works to be undertaken in the facility. I can say no more.

 

[DrADK]

I see....then it seems that you don't have any other option really......other than using the american code. I could suggest some other European codes but I do not think you can find them in English.

Since I am not that familiar with the UK construction system......aren't you going to have any problems with the British building authorities for using a non-British building regulation?

Good Luck!

It has become appallingly obvious that our technology has exceeded our humanity
- Albert Einstein

 

[fndn]

California is the most seismically active region in the US and so you may contact

http://www.seaoc.org

for more information. This will suffice the structural design end of things but you also need geotechnical parameters for which you should look at the DVDs at

http://www.soilstructure.com

Lastly

http://www.ppi2pass.com

has 8th edition book on seismic design of buildings which is very comprehensive. Due to the many checks in the applicable codes, you may consider a licensed structural engineer currently practicing in California to review your final design.