Engineering and economic feasibility of a new prefabrication ecosystem for steel construction in diverse low-rise residential buildings

The old urban fabrics of Iranian cities are characterized by diverse lot shapes and sizes, influenced by a long history of private real estate ownership. As a result, new residential buildings can only be designed and constructed as unique, one-off structures, reflecting the individuality of each site and the preferences of the owners. This complexity makes the adoption of mass production techniques, such as modular construction or prefabrication impractical and financially nonviable in renovation plans. On-site construction typically demands a highly trained and skilled workforce, which is often in short supply, particularly in less affluent neighborhoods where wages tend to be lower. Consequently, the challenge of delivering quality housing, which could otherwise be addressed through industrialization, has emerged as a significant concern in many cities across Iran. This has raised important issues related to social justice. To address this dilemma, this study aims to propose a new engineering ecosystem where slightly overdimensioned standardized members are used for buildings of different configurations that fulfill an envelope of specifications. Such members can be prefabricated in one factory and deployed to different building sites across the city, leveraging economies of scale to rationalize the cost. The research includes a comprehensive feasibility analysis focused on steel construction and special moment-resisting frame systems in low-rise individual buildings with diverse column layouts and number of stories. Moreover, comparisons between the standardized designs and conventional designs have been carried out in terms of structure weight and cost. Finally, considering the importance of deployment scheduling integration, a model has been developed to optimize the allocation of prefabrication factories to different construction sites to serve queues of registered orders. The findings indicate that, although standardized designs result in a 30% to 43% increase in frame weight and a 7% to 12% increase in total construction costs compared to conventional designs, they offer enhanced construction quality, improved seismic performance, and an 8% to 13% reduction in overall life-cycle costs of the structure.