Membrane Structure for Aesthetics and Longer Service Life Anti-Aging Technology for Bridges

While maintenance and inspection to protect aging civil engineering infrastructure is becoming increasingly important, an issue from the perspective of urban development is its impact on the landscape. While protecting its function as social capital, it must also be landscape-friendly. Taiyo Kogyo proposes “bridge wrapping” as one solution to this difficult problem. This is a cosmetic technology that covers bridges with membrane panels, applying membrane structural architecture, and contributes not only to landscape improvement but also to extending the service life of the structure itself.

Revitalizing the urban landscape to create an attractive city

As the civil engineering infrastructure built during the period of rapid economic growth continues to age, road landscaping has become a major issue along with its maintenance and management. Postwar reconstruction, infrastructure development associated with the Tokyo Olympics (1964), and rapid development. These efforts have produced economic growth in Japan that has astonished the world and greatly improved the lives of the Japanese people. However, it is also true that this rapid economic development has had a negative side. In 2017, Keiichi Ishii, then Minister of Land, Infrastructure, Transport, and Tourism, announced the underground relocation of the Metropolitan Expressway, which crosses over the Nihonbashi Bridge in Chuo-ku, Tokyo, saying, “The Metropolitan Expressway, which was urgently constructed in time for the recent Tokyo Olympics, has played a major role as the main artery of the capital city, Tokyo. However, the loss of the precious waterfront space and other damage to the urban landscape and comfort of the city have resulted. He then stated his intention to go beyond simply renewing the aging Metropolitan Expressway and work toward “revitalizing an attractive urban landscape.

Taiyo Kogyo proposes “bridge wrapping” using a membrane structure as a solution to the question of “how to effectively utilize current assets and pass them on to the future. A panel-like membrane material is attached between the main girders and on the side overhangs of bridges to cover the exposed structural parts. The material protects against dirt and corrosion, greatly improving the environment under the inorganic, dark image of the elevated structure, and can also be applied to inspection scaffolds.

(The Ministry of Land, Infrastructure, Transport and Tourism’s “NETIS (New Technology Information System)” registration form is included in “Metropolitan Highway and New Technology”).

Stadiums, arenas, stations Membrane structures used in a wide range of architectural applications

The membrane roof of the Tokyo Dome, completed in 1988, has never been replaced and continues to function well today, Since its completion in 1988, the membrane roof of the Tokyo Dome has never been replaced and is still fully functional today.

Characteristics of Membrane Structure 1 Lightweight and Flexibility

At 1 kg/m2, the membrane material is extremely lightweight compared to decorative materials such as steel plates. Because of its excellent deformation-following property, the membrane absorbs the force of earthquake shaking, thus greatly reducing the load on the substructure such as columns. Unlike glass sash and metal, even if it breaks, it is unlikely to fall immediately. Even if it should fall, the light and soft material is extremely unlikely to injure people or vehicles.

Membrane Structure Feature 2 Long Life

Membrane materials do not rust or corrode on their own, so they do not require painting, repainting, or other maintenance.

Membrane Structure Feature 3 Brightness Performance

The membrane material has a solar reflectance of approximately 80%, a UV cutoff rate of approximately 99%, and a visible light transmission rate of approximately 13%. Compared to other materials, the lower part of the membrane provides an extremely bright space.

Membrane Structure Feature 4 Designability

The light and soft material makes it possible to respond to a variety of unique design requirements, including curved shapes.

Membrane Structure Feature 5 Environmental Performance

Membrane materials are characterized by extremely low CO2 emissions throughout their life cycle, from manufacturing to disposal.

 

Our Eco-Mark certified products are 100% recyclable, meaning that all used membrane materials can be recovered and recycled as effective resources. The membrane material has a photocatalytic function using titanium dioxide. Photocatalyst has been confirmed to be effective in adsorbing and removing nitrogen oxides (NOx) contained in vehicle exhaust gas, and it is estimated that the amount of NOx removed per hour from 1000m2 of membrane material is equivalent to the removal of 2.2 passenger vehicles. Photocatalyst has a self-cleaning function that uses sunlight (ultraviolet rays) and moisture in the air to decompose contaminants adhering to the membrane, so it maintains its original beauty for a long period of time.

To a bright and oppressive-free space, transforming the impression of the elevated space.

Bridge wrapping is a technology developed to utilize the features of membranes shown above for road maintenance and landscape improvement. One of the most important features of the wrapping is the improvement of brightness under the elevated roadway.

The visible light reflectance of the membrane material is approximately 80%. According to our measurements, the floor illumination under the girders on a sunny day is 2800 lx without the membrane material, while the brightness under the girders with the wrapping is 7000 lx, about 2.5 times brighter. The bright space not only improves the convenience of pedestrians using the elevated railway tracks, but also enhances security at night.

 

The placement of the membrane material under the elevated bridge also has the effect of reducing the noise of vehicles traveling on the bridge (approximately -15dB). The smooth underside of the membrane also has the effect of smoothing the flow of wind and reducing wind shear noise.

 

Since the land under many elevated urban expressways is not used for direct traffic, there have long been calls for effective utilization of this land, but from the standpoint of road management, its use has been limited to a very small number. In 2009, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) issued a notice stating that the land should be used more effectively, including its provisional use. Although the bridge has been used for parking lots and bicycle parking lots in the past, the bridge wrapping will completely change the brightness, sound, and impression of the bridge. The high seismic performance of the membrane structure and the fact that the covered membrane material prevents road structural members from falling will also help to expand the use of the space to parks, nursery schools and kindergartens, which are in line with local needs.

Prevents corrosion and deterioration and greatly improves maintenance costs

Bridge wrapping, on the other hand, not only improves the landscape, but also improves the maintainability of the road structure. One of the causes of dirt under elevated structures is fecal damage caused by pigeons and other insects. In addition to the impact on passersby and aesthetic problems caused by droppings falling onto the elevated structure, leaving them unattended can also hinder visual inspections. In some cases, measures such as installing nets on the ceiling have been taken, but bridge wrapping completely covers the area under the elevated railway tracks with a membrane, so there is no need to worry about birds nesting or gathering. Chloride adhesion, which causes serious corrosion especially in coastal areas, can also be greatly reduced by covering with a membrane. Since anti-corrosion coating and periodic re-coating are no longer required for maintenance, it also contributes to maintenance cost reduction.

 

If the area under the elevated structure is a public roadway, vehicle exhaust gas is also a major cause of contamination. In addition to preventing exhaust gas contamination by covering the structure with bridge wrapping, the membrane material used for wrapping has a photocatalytic function, so that ultraviolet rays and moisture in the air can break down the contamination on the membrane, maintaining the beautiful scenery for a long time. The photocatalytic function also decomposes and removes NOx (nitrogen oxide), an air pollutant contained in exhaust gas. According to test data, the amount of NOx removed per hour is equivalent to that of 12.6 passenger cars.

High affinity with lighting Road structure becomes a city icon

橋梁ラッピングによる景観改善効果が顕著に現れる場所として、駅前、繁華街があげられます。都市部の高速道路は鉄道路線、駅上、繁華街を貫くように走っているケースもありますが、こうした場所に橋梁ラッピングによる明るい空間を生み出すことは、駅利用者、繁華街を歩く人々の利便性、防犯効果を高めるだけでなく、空間の価値を向上させることにもつながるからです。

たとえば地域再開発等と連動し、独特の曲面構成を施したデザインとすることで、道路構造体が街のアイコンの役割を担い、街の賑わいを生み出す効果も期待できます。また膜構造の特徴として、照明との親和性の高さがあります。商業施設などでは季節や催事に合わせたライトアップを施す事例がありますが、これを道路構造体に応用することで地域と一体となった振興策への貢献や、広告、道路情報、災害時などの情報提供機能を備えた、サイネージとしての利用も考えられます。

Maintenance of elevated structures will change. Membrane structures will be used for inspection scaffolding.

Membrane panels utilized in bridge wrapping itself maintain a certain level of strength and durability, but Taiyo Kogyo has further strengthened this load design to enable use as a permanent inspection scaffold (membrane inspection scaffold).

In the “Ministerial Ordinance Partially Amending the Road Law Construction Regulations” that was revised and enforced in 2014, Bridges, tunnels, etc. are required to be visually inspected in close proximity once every five years according to uniform standards set by the government. Inspection work to check for small cracks and other defects is extremely sensitive, and the conventional work environment is not always comfortable due to the dark environment.

Unlike aluminum panels, the membrane inspection scaffold is not a dark place despite being a closed space, and the soft diffused light through the membrane keeps the interior bright. Our measured values are 29,000 lx inside the overhang and 1,900 lx between the main girders, which is bright enough to ensure sufficient illumination in the work area. In addition, the diffused light transmitted through the membrane does not cause shading, which contributes to improved work efficiency, such as improved visibility when checking the work in hand. In addition, the membrane-type inspection scaffold allows inspection work to proceed without delay in windy weather and other conditions that would otherwise interfere with outdoor work.

summary

The use of membrane structures in road structures is not limited to the bridge wrapping introduced here. Diffusers to prevent glare on semi-underground roadways, snow shelters to prevent roads from freezing in winter, and shelters to prevent flying balls from golf courses, as well as toll gates, SAs, and PAs, are also used in many other situations.

However, the characteristics of the membrane structure, such as light weight, decay resistance, weather resistance, and translucency. Above all, when considering the landscape improvement and facility protection functions introduced in the bridge wrapping, the role played by membranes is not limited to the current situation. Taiyo Kogyo will pursue what membranes can do and what value only membranes can provide, and contribute to making roads, an asset indispensable to our daily lives, safer, more secure, and more comfortable.

 

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