(1) Except as provided in Sentence (2), buildings and their structural members shall be designed in conformance with the procedures and practices provided in this Part.
(2) Provided the design is carried out by a person especially qualified in the specific methods applied and provided the design demonstrates a level of safety and performance in accordance with the requirements of this Part, buildings and their structural components falling within the scope of this Part that are not amenable to analysis using a generally established theory may be designed by,
(a) evaluation of a full-scale structure or a prototype by a loading test, or
(b) studies of model analogues.