Is code of practice BS8110 seismically compatible 2

[azh]

Can anybody tell me if British Standard BS8110 (reinforced concrete code of practice)is seismically compatible ? If so what sort of richter scale can it stand? I am quite sure that the code did not specifically described seismic loading.
This question came to my mind because during one of the conferences I attended, most speakers discussed about how to detail the reinforcement in seismic prone structures without referring to BS 8110. And ironically, most of the detailings are already covered by BS8110.eg the requirement of closed links or stirrups in columns.
So, please can any of the experts clarify this query!And how about BS 5950 (steelwork)

 

[Qshake]

It is likely life-safety based if the code doesn't specifically address behavior (hinging) and level of service or performance. Most codes are life-safety as you would expect. Under life-safety, the structure should perform well in low seismic events, expect damage in moderate events and allow limited performance during large events such that people may actually survive within the structure despite severe damage.

 

[azh]

Thanks Qshake.What sort of range in the richter scale do you mean when you say low, moderate and large?

 

[Qshake]

AZH, here is what I define low, moderate and large (high)

4-4.9 - Low (light)
5-5.9 - moderate
6-6.9 - large

Major is anything at or above 7.0.

 

[azh]

Thanks a lot Qshake.
Sorry Qshake, but I like to ask you again, does this mean that during major events , structures designed under this code are not expected to be resistant?

I would like to request Carlbauer and IJR to chip in this thread please. Because both of you seem to be familiar with BS8110. Others are welcome !

 

[Qshake]

I am not familiar with the British Standard, but wish to note the code must extend basic life safety in order to mitigate the potential collapse mechanisms. To see if this is the case, take a look at confinement requirements, transverse reinforcing, splice locations, connections, end-panel treatment etc. Generally, if it leaves you with the impression that placing concrete will be difficult with all of the steel the it extends beyound life safety. X-)

 

[IJR]

Azh

Qshake has laid out the basics of seismic design pretty well.

I have with me a copy of BS8110 and a couple of texts I use occassionaly. No direct mention of seismic design. But I know that the code is not blind to seismic events. When I come across how it deals with it, I will post it here.

UK is not a seismic zone and in my last preliminary work for a factory in Manchester seismic design was not required.

To help you make a bold move:

You wil be surprised to learn that most codes have a lot in common when it comes to seismic design, and can be summarized as follows:
a)Determination of min seismic loads-This one is usually based on local data
b)Design (often detailing) to satisfy the selected life-safety criterion(See Qshakes comments)- This one can be handled by good knowledge of performance of a structure during seismic events, and most codes have a lot in common here.

If you are working with a consultant who works for the owner then he should tell you which local codes to use along with BS8110. You could also convince him to let you use Eurocodes 8 because Britain supports Eurocodes and is a major contributor. In the eurocodes 8, seismic design is well covered.

To summarize

a)Find the design seismic loads according to local codes and use BS with appropriate load factor(BS has that down)

b)Satisfy min force and detailing requirements according to local codes(This is where Qshake's confinement, transverse reinf etc come in)

c)In absence of local codes, use Eurocodes 8.

I followed a) and b) a couple of years ago when I was required use BS5950 in Turkmenistan, where russian code SNIP governs seismic design. Before using local codes try to find equivalence in material and quality specs between the two, because strength reduction factors (or material factor) may differ from area to area. Steel fabrication in US is not the same as in other areas and is usually a source of concern in codes. Especially with RC design this is more pronounced because tests make use of local grades of concrete and steel, and conclusions are made accordingly. In my case there was no problem and materials were well specified by the consultant.

Once I find more info on BS approach to seismic design I will post it here.

Good luck
IJR

 

[abhio]

Design for seismic events requires a dynamic analysis of the structure, which is not covered under BS 8110. The analysis is done by a number of methods viz: seismic coefficient method, response spectrum method and time history method. For all these methods, local variables of expected earthquake motion must be used to scale the applied load. In fact, in the time history method, the time history of earthquakes used is mostly that of 5 "standard" earthquakes including the Loma Prieta earthquake and the San Fransisco earthquake, suitably "scaled" to provide an approximation to earthquakes expected in the locality.
In most countries, the design codes (steel/concrete) are separate from the seismic analysis codes, and a special code is also prepared for "ductile detailing" for earthquake resistance.