Why Use Structural Steel in Bridge Construction?

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Resilience and Durability   

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In the United States alone, thousands of steel bridges are century old, including the historical, iconic, and epic Manhattan and Brooklyn Bridge in New York. Manhattan Bridge was built in 1909 while Brooklyn bridge was completed in 1883. With the right maintenance measures, these steel bridges have manifested extraordinary resiliency and durability to withstand harsh environments and extreme natural events.

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In Japan, the use of structural steel is favored by engineers not only for buildings but also for bridges because of its proven capabilities against seismic activities. With the aid of modern technologies in designing and advanced material engineering, the earthquake-prone country has built many popular and record-breaking steel bridges like the Akashi Kaikyo Bridge. The bridge has the longest span among suspension-type bridges in the world at a span of 1.9 kilometers. The Akashi Kaikyo Bridge is located in an earthquake zone and was able to survive an 8.5 Richter Scale magnitude during its construction, unscathed.

 

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Lightweight

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Steel bridge superstructures are generally lighter than other bridge superstructures of different material composition which typically result in smaller and less costly foundations. Lighter superstructures also reduce seismic forces by significant amounts which can be a major advantage in regions with high seismic activities.

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Shorter Construction Period 

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Take the Bailey bridge for instance, steel bridges has been instrumental since the World War-II because of their rapid assembly and ease of handling.

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Due to their modular design, steel bridge structures can be built quicker than employing conventional construction methods. In most instances, steel components and other smaller elements are fabricated off-site, simultaneously with other work scopes and then transported to the job site. Assembled in modules or sections of calculated weight, launching and installation of the bridge parts such as beams and girders can be done with ease, in matter of hours.

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Green Building Material

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Steel is one of the materials that are certified under the Green Buildings Rating System such as LEED (Leadership in Energy and Environmental Design). It is considered highly sustainable because it can be re-used repeatedly and recycled unlimited times without degradation of its mechanical properties.

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Since the wide production and usage of steel in various industries, overall carbon emission was found to be reduced by at least 36%. Steel production requires lesser energy, produces lesser waste, does not release harsh chemicals or toxins, and can be easily retrieved. Steel simply has many ways of minimizing environmental impacts.

 

Quality

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Steel bridge components are fabricated in highly regulated conditions and controlled environments such as in shops and warehouses ensuring high quality and degree of workmanship.

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High surface quality and highly defined lines and edges of steel also allows easier and effective implementation of inspection and quality control.

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Maintenance

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When required, steel bridges can be repaired while in service, and most probably not requiring complete replacement.  Components can be strengthened, moved, replaced, or modified without closing the bridge to traffic.

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All components and members of a steel bridge are visible, permitting easy detection of damages or signs of deterioration. Since all members are accessible, maintenance works like re-painting are not really complicated.

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Complex Geometry

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Steel bridges are not just strong yet durable structures that connects societies. Long ago, bridges have been fundamentally aestheticized and transformed into symbolic architectural landmarks and neofuturistic sculptural designs giving unique qualities to the urban and natural landscape.

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Structural steel bridge components can be fabricated and erected to unlimited ideas of complex geometrical configurations. Unimaginable turned into reality, these are some of the steel bridges that caught people in awe: The Three Graces, The Bridge of Light, Changsha Bridge, The Helix Bridge, and many more.

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Modification and Adaptability

 

Steel bridge can be modified to adapt socio-economic changes like deck widening to address increasing volume of traffic, or re-configuration of its structural integrity to cope up with changing load and weather conditions. Other materials do not have the same adaptability and oftentimes require replacement for new loadings or changes in configuration.

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Thanks to the weldability of steel which facilitates easier connections among structural steel members from different directions and angles.

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Long-span Construction

 

Structural steel bridge has the capability of covering a single span of over 500 feet, in the form of plate girders, tied-arches, suspension bridges, cable-stayed bridges, and trusses. The world’s longest bridge span is so far recorded by a suspension steel bridge with a length of 1.9 kilometers.

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The ability of steel bridge to stretch over longer spans eliminates extreme difficulties of constructing foundations in bodies of water, mountains, and protected natural areas. The elimination of expensive foundation works also means avoidance of negative impact to environment and wildlife.