## 5 Findings and Discussion
### Implications  
The application results of the fuzzy set algorithm refer to 57 sustainability indicators that span widely over three dimensions, namely social-technical sustainability (36 indicators), economic sustainability (10 indicators), and greenness (11 indicators). These dimensions stress the importance of technical concerns in achieving sustainability and thus better match the uniqueness of steel structures. This implies that all social-technical, economic sustainability, and greenness elements are necessary to account for the scope of the sustainable steel structure. The improved three dimensions provide a theoretical basis for exploring the sustainability of different structural types. The research findings suggest that different types of building structures may exhibit inconsistent sustainability performance, and different management measures should be taken to achieve sustainability in practice.  
The research findings imply that the divergent concerns between designers and constructors over the sustainability indicators are synthesizable by using a fuzzy set algorithm. The results also indicated that the sustainability assessment system for steel structures has shifted from a single view of design or construction to a synthesized one. While the fuzzy set algorithm is advocated to use as an alternative approach to improve current sustainability indicators, it is implied that the application of sustainable urbanization in this area should account for the uniqueness of steel structure projects. For instance, by absorbing designers and constructors' opinions, the sustainability indicators of steel structures have to consider a long product lifecycle and high steel structure performance.  
A large scale of steel structure projects is being initiated, but the relevant unsustainable accidents are enlarging in the meantime. Most of these accidents are due to designers and constructors who stay in their positions to implement and assess the steel project's sustainability. The synthesized sustainability indicators suggest that designers and construction parties should cooperate and communicate in advance, and provide implications for practitioners to integrate the views of both designers and constructors. The research findings would be a useful reference for other countries to develop a steel structure assessment system. Specifically, by using the indicator system, constructors can recognize unreasonable schemes and unbuildable steel structure components at an earlier stage. Thereby, reducing design changes, saving money and construction time, and using less materials will be actualized. The sustainability indicators help designers to understand the main concerns of constructors in the construction process, such as steel ductility, construction accuracy, and structure reliability. Besides, the client may find it supportive for assessing the potential performance of steel structures and gauging the design or construction phase deficiencies. Therefore, the findings can help to identify the inconsistency of designers and constructors in building steel structures and help to propose measures to alleviate these inconsistent problems.  
Furthermore, the above conclusions can be combined with information technologies to realize the integration of design and construction in the management process. For example, importing comprehensive indicators into the network information platform reminds both parties to identify contradictions and deficiencies in advance, which will help both parties to cooperate more efficiently. The platform can also transparently store and analyze a large amount of project information and data, which helps to explore the internal mechanism of the sustainable development of steel structure buildings. For example, the relationship between different types of indicators can be discovered through data analysis of the platform, which helps to realize the supervision and prediction of the cost, construction period, and quality of steel structure projects.