Structural frame selection processes: case studies of hybrid concrete construction projects

Selection of the most appropriate structural frame for a building during the conceptual design stage is crucial to the overall performance and value delivered to the client. Despite this, the decision making process is commonly characterised by subjectivity and heuristic reasoning making it difficult to map / analyse the factors underlying structural frame selection. This paper uses both live and retrospective case studies of Hybrid Concrete Construction (HCC) projects to gain an understanding of decision making for structural frames. These two case studies represent different building types: one is bespoke; and the other is a more standardised type of building. HCC comprises a combination of in-situ and precast concrete elements. Interviews with relevant members of the project teams were used as the main data collection technique. This paper explores various stakeholder views on the reasons for adopting a particular solution, and the particular challenges associated with the use of hybrid concrete. Although the small sample prevents generalisation to a wider population, the findings suggest that HCC is used for buildings where cost and time performance are not the most important criteria, but where architectural aesthetics and longer-term issues, such as sustainability prevail. Clients and architects were found to be the most influential team members in the frame selection process. Due to the increased complexity of HCC projects, team members need to be involved early and, most importantly, adopt a cooperative attitude which should be nurtured throughout the duration of the project. These findings provide useful lessons learnt and highlight the implications for practitioners using hybrid concrete structural frames in the future.