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Reciprocality Design Problem:

Design Philosophy:

The site is located at in China Mixia Village, Pinghe Township, Luchun County, Honghe State Yunnan.

Reciprocality 1. A form of mutual dependence or action or influence through which a relationship of mutual dependence is developed and sustained. 2. The supporting of the inanimate by the living and the supporting of the living by the inanimate. 3. A self-supporting process through which the principles of community, sustainability and environmental appreciation can thrive. 4. Each element is supported by the next, resulting in a rigid, overall interlocked approach.

The existing bridge (photograph below) is a simple bamboo structure spanning about 18m, at least 4m height over River Mixia with a central pier made from a bamboo basket filled with stones. However, the structure has to be repaired or reconstructed every year after the high water seasons when it is washed away by the decklevel river water. Without the bridge, movements between the three villages in the area are broken and schooling to children has to be halted.

This concept, along with the aims identified above provide the basis of the design approach and the framework through which a sustainable solution can be found and delivered. The approach has been applied to the design, construction and maintenance of the river crossing. The proposal will enhance the visual and physical relationships between the crossing and any surrounding features and uses. This holistic approach is valuable in developing design features that are not only functional but also improve the relationship between the river crossing and the surrounding community.

Design Response: The aims of this proposal are outlined below: 1. Cross the River Mixia using a minimal amount of resources. 2. Create a slimline structure that does not have an overbearing presence on the landscape, allowing people to appreciate the surroundings and to facilitate interactions between users. 3. Use simple engineering principles to create a functional and beautiful design. 4. Create a strong and secure crossing with the structural components integrated into the intended design and form. 5. Prevent or limit the rebuilding each year or see rebuilding as an event. 6. Avoid peak water flows, reducing the forces enacted on the structure. 7. Maintain and enhance physical and social links between the local communities. 8. Design a feature that becomes celebrated and cared for, a place to meet, educate and celebrate. 9. Encourage the dissemination of knowledge between the young and old, passing skills through future generations. 10. Create a crossing that reflects the local distinctiveness and is not an alien feature to the area.

This will be achieved through the careful design of the proportions and shape of the deck, supporting structure and the connections with the land. These elements are encountered visually from the wider landscape around the crossing and experientially from the crossing itself. The design considers both of these aspects with the aim of fully integrating with the surrounding area. To achieve the desired result the proposed structure is based around the reciprocal frame concept. A reciprocal frame is a self-supporting structure made of three or more beams and which requires no center support. Each element is supported by the next, resulting in a rigid structure.

Wu Zhi Qiao Bridge Design Competition

Bamboo construction has been used successfully for many years and will be used as the primary material for the structure. This philosophy respects culture and tradition and encourages local pride and ownership in the crossing whilst also being a structure that local people can maintain and repair on their own when required.

Community Benefit:

The design negates the need for central structural support, except during construction, preventing the River Mixia from exerting forces on the structure. The height of the crossing will avoid peak river flows during the wet season, preventing it from being washed away, maintaining connections between the surrounding communities.

The concept of reciprocal frames can be taught in local schools encouraging the learning of ancient Chinese architecture and also developing an understanding of how the River Mixia crossing is constructed. These projects can be done individually or in teams, depending on the scale, developing community spirit.

This design approach can be easily replicated or adapted for use in similar situations at surrounding locations or communities.

This is of value to the community as, when they grow up, the next generation will already have the skills not only to maintain the structure but also to build new ones without the requirement of external help.

Design Development: The models shown right explore the potential of reciprocal frames and present possible design solutions using them. They show how these self-supporting structures work and how they can be arranged to create a reciprocal frame crossing for Mixia. To increase the frame strength in real world applications it can be bound at the joints and the main structural components can be multiplied to create additional support. The deck of the structure can be attached directly to the frame resulting in a simple and functional crossing. The graphic below provides a summary of the design development and shows how community, environment and sustainability aspects have been considered throughout.

Context Community

The reciprocal frame has been used since the twelfth century in Chinese architecture and was also a concept explored by Leonardo da Vinci during the fifteenth century. The design is simple in form but effective in structure, making the most of the intrinsic strength of the materials used. This intrinsic strength reduces the need for over-exuberant structural components, resulting in a slim and elegant crossing that allows attention to be focused on the surrounding environment during use.

The simplicity of the design means it can be built at any scale by anybody. This has a range of benefits to the community as a whole.


Design Concept:


Three local villages use the crossing which consist of a diverse set of cultures.

The rebuilding of the crossing has become part of the local culture.

Local people live off and rely on the land for their health, food and wellbeing.

A functional feature is required that should also be something the local people can take ownership of.

Yunnan Province is the most biodiverse in China.

The River Mixia is a dominant feature.

The area contains farmland valuable to the local people and economy.

Steep topography limits access to the site.

Concept Create a feature that all three villages can appreciate and be proud of, encouraging use and interaction between them. See any yearly rebuilding or maintenance work as a tradition that is celebrated.

Work with the topography rather than change it and respect the power of the River Mixia.

Existing Crossing Low Water Level


Involve local schools and villagers to teach them construction methods. See the construction as an event rather than a process.

Plant bamboo for use in future maintenance and as a design feature. Take as little physical footprint as possible.

The area is subject to extreme weather events.

The surrounding land and environment is of high value to the local people.

Encourage biodiversity and make the crossing part of the environment rather than an alien object.

The current crossing is unsecure and needs to be rebuilt each year.

It is a difficult and timeconsuming process to rebuild the crossing each year.

Use locally available materials and grow new materials for future maintenance.

Create permanent elements that will not be washed away.

This increases the time and material resources used on the structure.

Limited construction materials are available locally, even bamboo comes from other villages.

Pass knowledge down generations through yearly maintenance and construction events.

Use minimal if not no resources that are not available locally.

Proposed Crossing High Water Level

Design & Construction

Protect and enhance the environment around the crossing.

Grow future materials for use in maintenance.

Sheet 1 of 2

Reciprocality Components:

Plan and Elevation:

Construction & Maintenance:

1:100 @ A2 2m deck width provides adequate space for both people and livestock. It will facilitate interctions and reduces the need for permanent railings

The deck will be constructed from short, thin lengths of bamboo laid permendicular to the external frame. This will provide a neat, compact and smooth surface which can be easily repaired in short sections. The deck will be attached to a thin frame which in turn is connected to the main frame below. The external frame will be constructed of thicker and longer lengths of bamboo organised into a reciprocal frame to provide the structural support. It will be fixed to the ground at each end to prevent movement and retain the strength of the structure.

Wu Zhi Qiao Bridge Design Competition


Bamboo planted near the crossing providing a gateway and resource

<0.5m height of the structure itself creates a slimline element that does not impose on the surroundings.

20m span in order to gain a clean footing at each side of the River Mixia

5m height from the bottom of the River Mixia means high water levels will not exert any forces on the structure

Materials: Frame Sides: 10 x 8-10m bamboo (100mm dia) Frame Centre: 5 x 2.5m bamboo (100mm dia) Deck Surface: 400 x 2m bamboo (50mm dia) Deck Frame: 10 x 5m bamboo (50mm dia) Length of rope to bind joints

The proposed crossing can be easily constructed by local people under the guidance of a technical expert. A simplified five-stage construction process is set out below: 1. Create a foundation / footing for the structure to rest on or fit into. 2. Build a temporary support scaffold in the river at low water level. 3. Place each length of bamboo in the correct positions in the correct order. Build from the centre towards the river banks. 4. Use rope to tie each joint together and hold them in place. 5. Remove the temporary support an tighten the ropes again (note, the ropes do not provide any structural support as the bamboo structure will support itself, the rope locks the bamboo in position to ensure that the strength is maintained). All materials for the initial construction can be sourced from nearby towns and villages. However, the materials for future repairs and maintenance will come from within 100m of the crossing, from the bamboo planting proposed. A handrail can be attached to the structure during the wet season if desired. This can be seen as an event to mark the changing seasons and place the crossing at the centre of local culture. The skills required to build the proposal already exist within the community, it is just the simple structural layout that will be taught which can then be passed down generations and used for other projects. The design uses a minimal amount of materials to create a simple, functional and locally distinctive crossing.

Proposed View

Proposed View

Existing View

Existing View

Sheet 2 of 2

Team No.38