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Re[2]: Seismic/Non-Seismic design

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>Petro-chemical process plants, electric power generation plants, and 
>other similar industrial "nonbuilding" structures share the same 
>concerns.  Concentric braced frames generally work the best to resist 
>the earthquake (regardless of zone) or wind forces.

......How so?

     
>Another major concern is the control of lateral drift.  Although the 
>pseudo static lateral loads are lower with EBF's or SMRF's it should 

.....I don't think there is a comparison between drift performance of 
an EBF vs SMRF. The latter IS designed to drift with integrity, and the 
former is designed for limited drift of concentric braced frames in 
addition when maintaining similar integrity as the latter.


>be noted that the better seismic performance is due to the ability to 
>absorb energy as the structure displaces laterally.  This displacement 
>can fracture piping and attachments, and put the plant out of service. 
>Evaluate the performance goals of buildings as opposed to the required 

.....in other words: for drift sensitive structures, limiting the drift 
is more effortlessly (more economically) accomplished using other than 
moment frames.     OK.


>performance of a process plant.
 
 >The lower R value (indicative of concentric braced frames as opposed to 
 >EBF's) implies more of a required elastic response.  The systems that 
 >dissipate seismic energy better also displaces more
 ..............yes, but it is much easier to control displacement of a braced 
 frame than it is a moment frame.
 
 >  Generally the best
 >seismic systems for industrial process structures are concentric braces. 
 
 .....................................I agree if building hight requires more 
 than one level of braces.
 
 >Within this family of systems you can still select a Special Concentric
>Braced Frame (which has good seismic performance with rather easy 
>detailing design requirements), the traditional X brace, single diagonal 
>brace, Chevron brace, etc.  Generally, I select from the family of 
>concentric braced frames based on the process piping requirements and 
>clearances.
     
>Occasionally I will use a moment resisting frame for pipe racks to 
>optimize piping layouts, but care needs to be exercised to accommodate 
>lateral drift and piping anchorage design.  Generally, if the piping 
>layout requires a moment frame, I will use an Ordinary Moment Frame as 
>opposed to a SMRF.  The penalty (lower R value) is generally offset by 
>the lower lateral drift and ease of design.


Do you know Sam Peiris? He used to work for B&V out of LA. If you know 
him please give him my regards.