General

This is a park gate for Longxing town in Chongqing China. The town is a famous as its buildings and streets of traditional Chinese styles, preserved from hundreds year ago. Since last 20 years, the town has been modernised with the development of the country. As a gate of a newly built park, its architecture characteristic is expected to reflect both modern development and local traditional aspects.

Figure 1: A traditional gate structure in Longxing Town, Chonqqing China

Figure 2: The park gate for Longxing Town, Chonqqing China

Excellence

Figure 3: The gate roof steel frame warped by FRC coating

Normally, the stability of a simple gate (as figure 1) relies on the fixed footings, requiring that the columns need to be embedded deeply into the foundation to obtain sufficient shear and bending stiffness. However due to the ground condition and construction quality, the simple gate may lost still stability under extreme load case (e.g. Gust wind).

In the structural design, the nonlinear performance of the gate has been fully taken into account. A small lateral displacement of the roof as a rigid diaphragm would make the short columns rotate significant angles from the vertical directions, and form hidden hinges with other columns which are still almost straight. Therefore the structure will become a braced structure instead of a sway frame.

The elegance of this structure is achieved using the safety margin from an instantaneous changeable structure, which pushed the boundary of the modern structural design principles.

Creativity and innovation

Figure 4: The steel roof frame warped by FRP cladding

This non-building structure consists of a double curved roof of anti-classic surface and vertical columns. Even though in form of instantaneous changeable structure, the structural stability can be easily achieved by the non-developable roof surface and steel pipes of varied lengths. Additional to the fixity of the joints, the significant lateral structural stiffness can be obtained by very little deformation of the vertical columns of short lengths without generating excessively large forces in the structure under large wind or seismic load.

Elegance and good detailing

A number of steel pipes of 60mm diameter and up to 10m height are post-installed as tensile elements between the roof and ground, creating an impressive view effect of the heavy roof supported by extremely slender and straight columns without structural buckling.

Figure 5: Extremely slender column of straight geometries.

Sustainability

Figure 6:The steel roof frame was lifted onto the place as one element

The whole steel roof fabricated in the factory, was lifting onto the position, significantly reducing the use of temporary false work and construction time. The connections between the roof and vertical columns are simplified since the structural stability does not only rely on the fixed connections of a typical sway frame. That would greatly benefit the maintenance and repair work, and also reduce the cost of the deconstruction after the design life ends.

Figure 7: Installation of the steel columns

Value

The park gate is located in the “mountain city” of Chongqing, where ground levels are complicated and varied. Just in the small area of the park, the ground level variance is up to 14m high. The gate structure has a roof of hyper shape, with a sloped profile of large level difference matching the key characteristic of the city. The fantastic gate structure contributes to the whole park project, and promotes the average building qualities for the local area, eventually greatly improve the relevant residential property sale of the Client.

Summary

This structure is designed following the requirement of the client regarding the local architectural aspect and modern construction, reflecting the local culture of the city. In structural aspect, the gate has an elegant geometry with the neat supporting system, and the stability is largely enhanced by the roof of the anti-classic geometry and the columns of variance length, which enable the structure obtain additional structural stiffness under small displacements without producing excessive forces. This design is a great attempt of using instantaneous changeable structure to enhance the stability of a non-building structural type, which was generally avoided by traditional structural design. Since the completing of the construction, the gate structure has successfully withstood the maximum wind and snow load as recorded in last decades