Study on the spatial structure and driving force of urban areas in Beijing based on building space structure

Quantitative study of urban spatial is the core content of urban geography research. Based on analysis of the building space structure, we explored urban spatial and its change rules. According to the characteristics of the building space structure,we designed a vector model to explore urban spatial structure. In this model, we applied three different polygon-based data, administrative districts, concentric circles and fan divisions, to respectively analyze urban construction center, urban construction direction and intensity of urban construction. The results show that this method well characterizes the change rules of Beijing urban spatial structure. The characteristics and rules reveal that:(1)Beijing city develops in a single direction because of the effects of urban function diffusion and agglomeration. The inner city expands to the outer city, and the outer city agglomerates to the inner city;(2) Due to the influence of the major events, urban area may expand to the opposite direction or form a bidirectional development;(3) The reason of urban sprawl in Beijing is not only the expansion of inner city, but also the agglomeration of outer city;(4)The urban area of Beijing city develops towards the air while sprawling, and the new denser urban regions tend to occur in the urban fringe;(5) Biaxial structure of Beijing urban area has been established, but west-east axis is more notable than north-south axis. Now, the differentiation of Beijing urban development in each direction is decreasing, and Beijing has a balanced development in each direction.