The success of optimal system selection depends on many factors, such as the nature of the project itself, design team collaboration, team leader's personality, and client input. Unfortunately, despite numerous existing studies on key impacting factors in various fields of construction design, the majority of them failed to focus on the key factors affecting the structure design decision-making process. This study aims to identify, investigate, and rank factors perceived to affect decision-making for the optimal system in the construction industry, particularly that of buildings, during the ea...