This report outlines the findings of two independent studies by PTL Structural Consultants (PTL) and Holmes Consulting LP
(HCLP) which have validated the use of an earthquake induced lateral force distribution, develop by Dr D.
Gardiner (at University of Canterbury). The method for determining the lateral force distribution for
designing the diaphragms of buildings is known as “the pseudo-Equivalent Static Analysis (pESA)”.
In the Canterbury Earthquakes it was observed that reinforced concrete coupled wall buildings displayed more strength and lower ductility in comparison to their design intent. As an approximate method to account for axial restraint in the design of coupled walls it is recommended that a redistribution of design demands be used to reduce the coupling beam design capacity and to achieve a more desirable coupled wall behaviour.