## 2 Literature Review
### Synthesizing the Perspectives of Designers and Contractors in Sustainability Attainment  
In appreciating the complexity of steel structures, designers and constructors are increasingly aware of the need to invest in sustainable practices. To this end, designers' intention should be realized by constructors, while the constructability issues of steel structures should be evaluated in the design phase ([PERSON] and [PERSON], 2016). The design stage is dominated by designers who provide design solutions (e.g., building size, function, landscape, and facilities) based on the clients' sustainability requirements ([PERSON] and [PERSON], 2016; [PERSON], 2016). Meanwhile, constructors take the responsibility of satisfying clients' sustainability requirements at the construction phase, such as reducing carbon emissions, decreasing wastewater discharge, improving constructability, and ensuring timely delivery ([PERSON] and [PERSON], 2016). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Indicator** & **Code** & **Indicator** & **Code** & **Indicator** & **Code** \\ \hline Shape Coefficient of Building & x\({}_{1}\) & Inter-Story Displacement Angle & x\({}_{0}\) & Stress Relaxation of Components & x\({}_{19}\) \\ Earthquake Fortification Intensity & x\({}_{2}\) & Structural Disaster Resistance & x\({}_{11}\) & Fatigue Strength of Components & x\({}_{20}\) \\ Coefficient for Importance of Structure & x\({}_{0}\) & Structural Constructibility & x\({}_{12}\) & Ultimate Strength of Steel & x\({}_{21}\) \\ Bearing Capacity of Structure & x\({}_{4}\) & Functional Variability & x\({}_{03}\) & Steel Yield Strength & x\({}_{22}\) \\ Energy Consumption Capacity of Structure & x\({}_{5}\) & Structural Adaptability & x\({}_{44}\) & Ductility of Steel & x\({}_{23}\) \\ Vulnerability of Structure & x\({}_{6}\) & Living Comfort of Steel Structure & x\({}_{55}\) & Fire Resistance and & \\ Structural Self-Reposition & x\({}_{7}\) & Matching between Structure and Architectural Function & x\({}_{6}\) & Construction Accuracy & x\({}_{55}\) \\ Natural Period of Vibration of Structure & x\({}_{8}\) & Deformation of Structural Members & x\({}_{72}\) & Reliability of Construction Plan & x\({}_{62}\) \\ Lateral Displacement Stiffness of Structure & x\({}_{9}\) & Deformation of Non-Structural Components & x\({}_{83}\) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The social-technical sustainability indicators. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Indicator** & **Code** & **Indicator** & **Code** & **Indicator** & **Code** \\ \hline Pre-Consulting Fee & x\({}_{29}\) & Transportation Cost of Steel and Components & x\({}_{00}\) & Repair Cost & x\({}_{03}\) \\ Design Fee & x\({}_{28}\) & Operation Cost & x\({}_{31}\) & Dismandling Cost & x\({}_{04}\) \\ Procurement of Materials & x\({}_{29}\) & Maintenance Cost & x\({}_{02}\) & Installation Cost & x\({}_{05}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The economic indicators. In traditional procurement systems, clients enter into contracts with designers and constructors separately. Such a project delivery mode leads to potential conflicts between these two entities due to their different perspectives in serving clients. Empirical studies have shown that the lack of effective interactions and poor teamwork between designers and constructors cause unsustainable problems (e.g., rework, low quality, change orders, schedule delay, and cost overrun) [31; 32]. To resolve such issues, [PERSON] [33] suggested that constructors should be involved into the design phase and designers should also extend their services forwards to the construction stage. Thus, the sustainability of steel structures will be attained by keeping both designers and constructors working consistently. On many occasions, construction plans, and detailed drawing schemes are mistakenly followed after the design phase [34]. The involvement of constructors in the design stage helps to improve the design quality by integrating the expertise of contractors in design solutions.