Spatial performance evaluation and optimization of integrated aboveground and underground spaces in urban commercial complexes

As urban areas experience economic growth and expansion, the development scale and intensity of urban commercial complexes have notably increased. Integrating aboveground and underground spaces enhances the vitality of the latter, thereby improving land development efficiency. However, these complexes encounter challenges, including disconnections in design, leading to poor underground continuity and suboptimal economic outcomes. Existing research predominantly discusses individual factors influencing aboveground and underground space integration, lacking a comprehensive assessment framework for integrated urban commercial complex development. This study introduces a spatial performance evaluation framework encompassing four key dimensions: functional spaces, transportation systems, public spaces, and landscape environments. Representative cases of three complex types - courtyard-style complexes with inward aggregation, courtyard-style complexes with outward radiation, and inner street-style complexes - are selected for spatial performance evaluation. Findings indicate that public space and transportation system performance exert the most significant impact, while functional space and landscape environment performance have a relatively smaller influence. Considering the distinctive characteristics of integrated aboveground and underground development, we propose prioritizing public spaces and transportation systems, emphasizing functional spaces, and advocating a balanced approach to landscape environments. Specific optimization directions for selected case studies are outlined. The study's conclusions guide the scientific development of integrated spaces in urban commercial complexes, ultimately enhancing overall efficiency.