Perspective discrepancy between designers and constructors on the sustainability of steel structures: Are they synthesizable?

City growth and its resulted environmental issues are promoting a citywide application of sustainable steel structures. However, designers and constructors often hold conflicting perspectives on the sustainable construction of steel structures, which has been identified as a barrier to achieve sustainability in this area. Given that the existing sustainability indicator systems of steel structures are either design-oriented or construction-driven, this study aims to develop a new one by synthesizing both designers’ and contractors’ opinions in the development of such indicators. Semi-structured interviews were conducted to identify potential indicators. A questionnaire survey was then used to collect the viewpoints of designers and constructors on the identified indicators. Finally, a fuzzy set algorithm and hierarchical clustering were employed to detect the indicators’ relationships. The results present a three-dimensional indicator system composed of social-technical sustainability, greenness, and economic sustainability. Furthermore, it is found that designers and constructors have discrepant opinions on social-technical sustainability and greenness, while their views on economic sustainability are similar. The research findings provide managerial hints to the attainment of sustainable steel structures and enhance stakeholders’ understanding of design-and-construction integration in steel structure projects.