Is There a Regulation in the Expansion of Urban Spatial Structure? Empirical Study from the Main Urban Area in Zhengzhou, China

The city is a fundamental regional unit of development. Urban spatial structure is a relationship performance among the physical environment, functional activities, and cultural values. Identifying the urban spatial structure and functional areas accurately is of great significance for optimizing urban planning and promoting urban development. Previous studies have focused on the distribution for the single-functional area in some big cities and urban agglomerations from a view of a static time node, with little focus on multifunctional areas’ distribution from the perspective of comprehensive evolutionary in underdeveloped regions, especially in provincial capitals in the Central Chinese region. Therefore, taking Zhengzhou, a representative National Central City in the undeveloped central part of China as an example, we investigate urban spatial sprawling in the main urban area. Our interest is twofold. Firstly, we investigate the urban center as to whether, and to what extent, scaling in the spatial structure. The second point of importance concerns the comparison of specific types of functional area in the spatial structure and morphology from a microlevel perspective. The identification framework has been constructed to identify and evaluate the urban spatial structure. The research shows the following: (i) There is a strong correlation between the urban center which is extracted and the density in spatial distribution. The density value of POIs decreases from the urban center to the suburbs. This result is in line with objective facts. (ii) The urban center area has expanded by 25.16 km 2 in 2 years. In the center of the main urban area of Zhengzhou, it is generally accepted that the spatial structure pattern monocentric, but is polycentrically patterned in function. The compactness is increasing in the urban center area. (iii) By identifying the mixed functional area, it presents a circle-layer expanded layout with the comprehensive functional area as the core in 2016 and 2018. The comprehensive functional area has developed significantly and maturely, and in the multifunctional area, the development of the public–residential–business functional area and the public–residential–leisure functional area is relatively mature. In short, this study not only helps strategic planners to strengthen refined management, practical planning, construction, and management integration but also to assess whether policies or actions have been delivered as effectively as planned by identifying the urban spatial structure and revealing the evolution regulation.