Why pacific regions using wall stirrups? American and European designers are not.

Question

About building design......

Answer 1

Asia Pacific lies in what they call 'the ring of fire'. An area of frequent earthquakes and volcanic eruptions.

Stirrups and ties constitute one of the most critical factors of quality and antiseismic strength of buildings. Essential factors for the liability of stirrups are the proper hooks at their ends and the bend diameter at corners. The hooks at the end of the conventional stirrups are absolutely necessary for ensuring the proper functioning of the stirrup or tie in case of a very strong earthquake, when the spalling of the concrete occurs and when the hooks is the only remaining anchorage mechanism.  

Answer 2

Structural engineers and architects have determined (thru various tests and programs) that wall stirrups may be redundant to ensure integrity of building designs at specified level of damage (e.g., at 50-psi level).  However, wall stirrups are still being used by some as added safety factor just so there will be no premature failure at higher overpressures.

Here in the States, these guidelines (e.g., minimum grade number of wall stirrups to use; usually No. 3) are outlined in each State's Building Regulatory Code.  Some States regard the wall stirrups as options, mandating instead that other reinforcement material(s) be used.

I'm guessing the use or non-use of wall stirrups is a matter of difference between old school and modern technology.