Improving Global Quality of Life
Improving Global Quality of Life
Improving Global Quality of Life
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9 Needs and challenges <strong>of</strong> major industry sectors for future applications<br />
Bridges are classified as redundant and non-redundant. With non-redundant bridges, certain elements are<br />
deemed “fracture critical”. If fracture critical elements fail, the entire bridge is expected to collapse. The<br />
foregoing challenge <strong>of</strong> inspection is all the more critical for such structures.<br />
A major challenge to steel buildings is corrosion. Bridges have been painted for years, but painting is expensive,<br />
not only for a new structure, but as an ongoing maintenance cost <strong>of</strong> existing structures. The greatest cost<br />
is when severe corrosion is not detected and members fail due to loss <strong>of</strong> section. Weathering steel has<br />
been used successfully in some applications although it <strong>of</strong>fers no advantage in situations involving salt<br />
spray. Hot dipped galvanised members have also been used, but the economics are typically unacceptable.<br />
Thermal Spraying with corrosion resistant materials is yet another technically viable option that lacks cost<br />
effectiveness. New materials with better corrosion resistance or more viable coating methods will result in<br />
better bridge systems and will expand the role for welded metallic structures.<br />
The development and refinement <strong>of</strong> fatigue enhancement methods, both for existing structures as well as<br />
new structures is an ongoing opportunity for the bridge segment. For more widespread application <strong>of</strong> such<br />
technologies, the degree <strong>of</strong> enhancement must be carefully defined, and the means <strong>of</strong> application must be<br />
safe, practical, repeatable and verifiable.<br />
Breakthrough designs are needed to make steel bridge construction more cost effective with concrete<br />
alternatives. Such advancements will likely make use <strong>of</strong> other than I-shaped girders. Innovative composite<br />
designs with concrete filled tubes for example should be pursued. As the strength <strong>of</strong> steel used is increased,<br />
welding-related problems such as fabrication cracking and in service fatigue will be <strong>of</strong> greater concern.<br />
Fracture mechanics analysis suggests that as material toughness levels are increased, there exists the potential<br />
for increases in allowable stresses, or relaxed inspection and acceptance criteria. Accurate characterisation<br />
<strong>of</strong> material properties, particularly for multiple pass welds and for heat affected zones, as well as accurate<br />
models for prediction <strong>of</strong> fatigue cracking may reduce the frequency for ongoing in-service <strong>of</strong> bridges.<br />
Bridges are essential to the transportation <strong>of</strong> goods and people. No form <strong>of</strong> surface transportation can<br />
survive without them. Bridge needs vary from country to country (for example in financing, planning,<br />
method <strong>of</strong> construction, and maintenance <strong>of</strong> bridges), but all nations have strategic issues in common.<br />
Rather than routine engineering details for designing, construction and maintenance <strong>of</strong> bridges, focus on<br />
the strategic goal <strong>of</strong> what one may call “transportation solutions” that are vital and significant but more<br />
importantly that are influenced by the bridge industry and particularly relate to welded steel bridges and<br />
welded products, is dealt with here.<br />
To advance integrated bridge technology to meet transportation needs for planning for long lasting<br />
bridges, several factors must be considered:<br />
The impact <strong>of</strong> growing population.<br />
The need to travel faster but safely and efficiently.<br />
A greater emphasis on protecting the environment.<br />
Information that is available to practicing bridge engineers today through research and technology<br />
developments.<br />
New avenues and values because <strong>of</strong> expedient communication and globalisation.<br />
These factors, in addition to the routine considerations for cost effective bridges using conventional<br />
standards for design, construction and maintenance, are significant in meeting challenging demands <strong>of</strong> the<br />
communities that must be considered and supported by the government, bridge industry and academia in<br />
a coordinated manner to meet today’s demands on bridges.<br />
Through Optimum Use and Innovation <strong>of</strong> Welding and Joining Technologies<br />
<strong>Improving</strong> <strong>Global</strong> <strong>Quality</strong> <strong>of</strong> <strong>Life</strong><br />
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