This Futuristic pedestrian suspension bridge utilizes solar panels that absorb diffused as well as reflective light.

Photos by Margot Krasojević
T he brainchild of Margot Krasojević Architects, which specializes in hydroelectric architecture, the Piezoelectric Pendulum Bridge in Tianmen, China, spans two mountains and boasts a design that simulates the surrounding snow-capped mountain landscape. It responds to the cloud-edge effect, capturing direct and reflected light to increase solar energy production. On cloudy days, its solar panels absorb diffused as well as reflective light to allow the bridge to achieve maximum exposure to solar energy. In addition, its canopy is clad and fabricated with a highly reflective shifting carbon-fiber aluminum composite embedded with photovoltaic and piezoelectric cells.

Standing 650 feet above the ground, the bridge provides pedestrians with a birds-eye aerial view that changes with the weather. The unique design creates an illusion that seems to camouflage the bridge amidst the clouds and environment.

Naturally there were distinctive challenges involved in the bridge’s design, which was initially started in 2015.

Maintaining static equilibrium balance and counterbalance is of structural importance, as the height – along with the exposure to elements – creates an unstable environment.
With rotational inertia a primary concern, integrating swinging cantilevered walkway lengths stabilizes the structure as well as increases the moment of inertia without making it rigid — similar to the experience of a tightrope walker. The design moves and sways gently, which is a response to the upward air movement and cloud formation, offering pedestrians spectacular views as well as exposure to the very nature of the site.

Two interlaced footpaths are suspended from the structural axes of rotation, which dislocate and shift to rebalance the bridge, allowing for a safe crossing. The canopy structure then fragments in order to recalibrate the shifting weights along the bridge’s cross-section in a more efficient manner. This counterbalance is directed by the bridge’s pendulum weights suspended beneath the structure, which tighten and shift to restore equilibrium and maintain structural stability.
Balance is retained and controlled by the cantilevered elements that swing slowly and methodically to reinstate the bridge to a stable horizontal position.

The canopy’s dislocating fragments are clad with a carbon fiber-reinforced aluminum composite, which is lighter than aluminum, flexible enough for the cantilevered movements yet stronger than steel. This helps in limiting wear and tear in addition to providing stability through 45-degree torsions and adapting to the external forces of the cantilever frames’ movements while accommodating complex shifting shapes.

On cloudy days, its solar panels absorb diffused as well as reflective light to allow the bridge to achieve maximum exposure to solar energy.
In addition, a motion-capture system records the canopy movements, choreographing the synchronicity between the edge cloud cover, solar panels, and footpath walkways made from steel-framed sections lined with rubber to absorb unnecessary load-bearing changes that might arise due to the bridge retaining horizontal inertia. Self-healing polymers have been used to support internal mechanisms and slide surfaces seamlessly to transfer loads between separating canopy elements and skeleton frames. Furthermore, the canopy’s structural deformity under load has a series of polymer sheaths inbetween the separating elements that protect the design from wear and tear, similar to an airplane’s wing.

The canopy also shifts with passing clouds, revealing glimpses of the horizon and views visible for one minute and lost in the next. Light levels are monitored using sensors across the cross-section of the bridge, which anticipate a break in cloud cover to expose the natural surrounding landscapes in the process, underscoring the co-existence of natural and artificial phenomena.

Over the past five years since the project was first started, the bridge continues to be in the process of being technologically revised to be more dynamic and energy-efficient. The bridge moves with air currents, and like mountain climbers, the people crossing this bridge are exposed to the natural elements. Harnesses are available for use when crossing the bridge, but are not mandatory.

Shifting canopy elements resemble solar kites embedded with photovoltaic cells; these are lightweight, durable, non-corrosive, and highly reflective, creating a continuous surface cantilevered from the primary axial structure. These solar kites are CNC-fabricated and can be positioned in several configurations depending on the structural frame. Lightweight yet durable, these canopy elements split apart and can be easily locked into position. For a static surface canopy, there are laser-cut sections that can be repositioned as well as replicated for other sites and programmatic uses.

Digital fabrication is another essential construction technique employed in this project; all elements can be replicated and replaced cost-effectively and can be adapted to different scales. The bridge also generates electrical power, making it easier to structurally maintain it by keeping those fabrication tools on site. Moreover, the bridge is self-motorized with direct and cloud-edge solar power that generates enough electricity to animate, float, and mechanically move the structure in order to restore balance by shifting dynamic loads.

The colorful mural along the wall inside Fred’s Restaurant appears to “glow” thanks to the illumination provided by concealed lighting fixtures and those accenting the decorative coves on the ceiling.
Semi-conductor piezoelectric crystal cells are applied as gate voltage to the design, embedding them within the canopy and walkway to generate electricity through resistance. When mechanical pressure is exerted on these elements – for example, as pedestrians walk across the bridge or environmental mechanical dynamics alter the direct pressure on the fragmented canopy – the piezoelectric cells change the resistance, generating and releasing direct electrical current to the motor in order to move the structure. This type of electronics maximizes the efficiency of generating power as a direct response to instability in design and context. In short, the piezoelectric pendulum bridge uses a natural equilibrium to monitor and capture electrical energy from either solar or mechanical movement while trying to stabilize the momentum of inertia so that it can function safely as a footpath and observation deck. The dual nature of the design responds directly to its immediate context.

As of press time, an expected date of completion has not been released for the Piezoelectric Pendulum Bridge.

ABOUT THE ARCHITECT

Margot Krasojević completed her architectural education at the Architectural Association School of Architecture and University College London. She worked with Zaha Hadid Architects and was lead undergraduate and masters studio director, investigating digital and sustainable design programs at UCL, University of Greenwich, and University of Washington. She then opened a multidisciplinary architectural design studio focusing on integrating environmental issues, renewable energy, and sustainability as part of the design process.

Krasojević is currently working on projects in Asia, where she is integrating and harnessing renewable energy as part of a buildings service infrastructure. She is also designing hydroelectric homes and hotels, which redefine how not only tourism but everyday rituals are affected. Krasojević is investigating hempcrete as a sustainable and carbon-negative building material in her project for Catalonia’s Cannabis agricultural farm design.

Krasojević won the 2018 LEAF Award for “Best Future Building – Under Construction and Drawing Board” for her Self-Excavation Hurricane House in Louisiana. Her Hydroelectric House design is a permanent exhibit at The Futurium in Berlin, Germany. She was nominated for the Energy Globe awards 2020 and her Turbine hotel is part of a TV documentary by RAUM Films in Austria.

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