Architectural design

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Over the past 20 years, our country has built a large number of urban squares, which have significantly changed the situation of traditional cities lacking public spaces. At the same time, they have also altered the spatial structure of cities and influenced people’s lives. Apart from playing a role in regulating spatial density in cities and highlighting important buildings, these squares rarely serve as actual venues for the daily activities of citizens. Plazas with a single design and lacking behavioral support truly end up being neglected. The need for diverse functions in a plaza requires that many of these functions be integrated together. The variety of functions in a plaza determines the diversity of its space, and therefore designers should use indirect methods of spatial separation to ensure that each type of space has its own designated area where it can function effectively. There are essentially two methods for functional integration through spatial separation: one is in the horizontal plane, and the other is in the vertical cross-section. The best approach to adopt in design depends on real-world conditions, requiring a case-by-case analysis. 1 Separation of spaces (in the case of commercial plazas): Nowadays, it has become one of the social functions that large plazas must fulfill, as businesses use these plazas to carry out promotional activities for their products. However, such promotional activities often do not complement the square’s normal functions. On these promotional days, colored balls, banners, and flyers become the main features of the square, while the sound of speakers, music, and drums replaces the gentle sounds of pigeon whistles. This situation causes trouble for both the square managers and ordinary citizens. Take Shijiazhuang Cultural Square as an example: on average, there are more than 110 promotional activities held there each year. Apart from the over 50 artistic performances held during the “Colorful Weekend” events, most of these activities are promotional in nature. Such a high number of promotional activities makes the square resemble an outdoor market. ”Appropriate promotional activities are a good thing in themselves, but disrupting the public’s regular use of the square will inevitably lead to complaints. Therefore, for such incompatible and heterogeneous functional activities, designers should designate dedicated spaces for them, carry out necessary spatial organization, and confine them to specific areas. The “Public Welfare Plaza” in Hangzhou’s Wushan Square is a great example of this. The design designates a strip of land near the entrance to the plaza at the foot of the mountain as a \"community plaza.\" Through simple spatial separation and appropriate shading, this plaza at a lower elevation occupies a prominent position, making it easy to attract people’s attention and facilitating the conduct of community and promotional activities, without causing any interference with the use of the main part of the plaza. 2. The composite urban plaza in cross-section serves as a hub for urban functions; in addition to traditional roles such as leisure, culture, and social interaction for citizens, it functions as a node in the city, undertaking tasks such as transportation transfer, urban parking, and even serving as a commercial and entertainment center. To secure more urban space and integrate complex, diverse functions, extending plaza spaces into the third dimension and making use of cross-sections has become an inevitable trend in the design of large-scale plazas. The sectional composite approach allows the functional aspects of the domain surface and its architectural functions to be separated or combined, as well as brought closer together or kept at a distance, offering considerable flexibility. Its advantages in terms of functional integration for plazas are unmatched by any other spatial organization approach. In terms of specific methods, they can be divided into three types: integration underground, integration above ground, and simultaneous integration underground and above ground. (1) Integration into the ground is the most common method, as seen in places such as Shanghai People’s Square, Jinan Quancheng Square, Xi’an Bell and Drum Tower Square, and Shaoxing City Square. The number of underground levels in such plazas can vary depending on the specific circumstances; it is usually one level, but in some cases it can reach three levels (as in the Xidan Cultural Plaza in Beijing), or even four levels (as in the plan for Tianfu Plaza in Chengdu). Firstly, the advantages of underground integration: ① For plazas with subway transfer functions, the underground integration approach allows for a good degree of integration with subway spaces, making it easier to manage the relationship between the subway station and the plaza. ② It has a minor spatial impact on the plaza surface itself. If the design aims to eliminate any visual obstructions in the plaza and achieve a completely open spatial feel, an underground complex layout can be chosen. ③ The number of layers in the downward composite can vary; the functional capacity of the additional building spaces beneath the plaza area is highly adjustable, providing sufficient flexibility to support the development of the city. ④ Underground spaces are enclosed and less affected by surface climate changes, allowing for energy savings. The development of the multi-level underground space at Beijing Xidan Cultural Plaza is a success story; its three-story underground shopping mall connects various shops as well as subway stations, bringing new opportunities for the development of the Xidan commercial area in Beijing. Secondly, the limitations of underground composite construction: ① The large volume of earthwork in underground projects leads to **increased costs and technical difficulties**. ② For some special site conditions, the development of underground space involves significant damage to the site’s ecological conditions. Jinan Quancheng Square is located near Baotu Spring, known as the \"best spring in the world\". The construction of its underground facilities has had a certain impact on the underground spring system, which undoubtedly adds to the problems faced by Jinan’s already dwindling natural underground springs. ③ Excessive development of underground space will inevitably place excessive strain on traffic and municipal facilities in the city center. The plan for Chengdu Tianfu Square, which features four levels of underground space covering 185,000 m2, has drawn a lot of criticism. Many experts point out that there are already three major shopping areas in Chengdu’s old city center, so it is not reasonable to build such a large commercial complex. (2) Composite towards the ground surface; this type of sectional composite is not yet common. Based on the proportion of the upward-combined area relative to the entire square, it can be divided into two different types: partial upward combination (the Taizhou Citizens’ Square plan) and overall upward combination. The overall upward composite approach is generally adopted to completely separate pedestrians in the plaza from urban rapid transportation, and is suitable for traffic plazas of limited size. The partial upward compounding of the plaza is a type with even broader application potential and prospects. Based on the different locations where the plaza is elevated, it can be further divided into central elevation (the Taizhou Citizens’ Plaza plan) and elevation on one side (Anji Ecological Plaza, Yancheng Jiefang Road Plaza). Firstly, the advantages of combining it above ground: ① Compared to underground projects, it saves on investment, reduces the amount of earthwork required, lowers the technical complexity, and causes relatively less damage to the ecological conditions of the site. ② A local elevation of the space allows the plaza to span urban roads, serving to integrate spaces that are separated by such roads and thus lack continuity. ③ The local elevation of the space allows the plaza to be connected to the surrounding buildings at various elevations, **strengthening the connection between the functions of the plaza area and those of the surrounding buildings, which facilitates the formation of a functional complex comprising the plaza and the buildings. ④ It completely breaks away from the traditional two-dimensional spatial form of urban plazas, turning them into true “three-dimensional plazas” and “spatial plazas”. It has secured greater freedom in the design of the plaza’s spatial landscape. Designers can fully utilize their imagination to create a variety of terrain contours in the plaza, offering users rich and diverse vertical variations as well as landscape experiences. Second, the limitations of integration with the ground level: ① Poor integration with subway transportation. ② Due to the impact on the landscape of the plaza area, generally only one layer can be added above the ground, which limits the architectural space available beneath the plaza and reduces the flexibility in terms of functional capacity. ③ The impact of the side surfaces of the elevated portion of the plaza on the plaza’s landscape imposes higher requirements on design. If handled improperly, with too much rigidity and a lack of hierarchy, it will inevitably result in certain areas of the plaza becoming enclosed, oppressive, and lacking in openness. (3) Composite simultaneously underground and above ground. Digging down half a layer and lifting up half a layer, while combining actions both underground and above ground, represents a compromise between the first two methods. Its advantages and limitations also counterbalance those of the first two composite methods; an example of this can be seen in Anyang Central Square in Ruian, Zhejiang. Here, special emphasis is placed on the series of softening techniques employed in the design of the side interfaces of the elevated section of Anyang Central Square. The designer treated the side surfaces as tiered, sloping green spaces, and used gentle steps planted with trees to connect the lower and upper elevations of the plaza area, thereby effectively avoiding any obstruction to people’s lines of sight caused by the raised sections of the plaza. (4) The proportion occupied by the composite space. The method of composite sections generally appears only in the local spaces of plazas. Large squares are enormous in scale; it is neither possible nor necessary to cover the entire square with “double-layer” or “multi-layer” spaces. So, what proportion of the square’s total area should the projected area of the composite space account for? The larger the overall scale of the square, the lower the proportion of the projected area of the composite space relative to the total area of the square ； Conversely, it is a bit higher. The minimum proportion of the projected area of the composite space to the total area of the plaza is 15%, while the maximum should not exceed 60%. If it is less than 15%, the efficiency of spatial composite utilization is significantly low, making it uneconomical. Over 60%, the plaza has completely become an \"accessible roof\". Planting trees requires more than 2 meters of soil covering, which is not conducive to the fulfillment of the square’s ecological functions. In the Xi’an Bell and Drum Tower Square, this figure reaches 72%, which directly results in too few tall trees in the square; there is no shade during the summer, making it difficult for people to stay there. 3 Conclusion A city square can be understood as a complex of material and non-material elements. Firstly, urban squares possess urban values, namely their significance in controlling urban space and their own characteristics as public social spaces. It is both an urban design element and a multifunctional social institution ； It is a public open space integrated into the urban fabric, which meets people’s needs and influences their behavior ； It is the core of cities and urban public life; it represents social integration.