Civil Engineer Expert

Oldcastle Materials Inc. considers rebuilding larger wheel loaders when they reach the end of their first life.

Extreme maintenance practices can help you extend equipment life spans — but be aware you are managing risk.

In today’s economy, we’re all trying to stretch things as far possible. Whether it’s stretching time between oil changes in your car or holding off on buying that new pair of work boots you know you need, we’re pushing the limits.

The construction industry is no exception. Its economic downturn has prompted many contractors to run equipment for more hours than normal. Capital for new machines is scarce so equipment is being kept longer and worked harder. Knowing that the equipment has to last, managers carefully watch oil samples for wear particle signals that mean component failure is approaching. And some equipment managers are even replacing small components, such as water pumps and alternators, before they fail.

“We’re probably adding 20 percent more to the life of our equipment than we would in normal economic times,” says Rex Davis, a vice president at RMCI Inc., Albuquerque, N.M. “Sooner or later we have to make some decisions (about trading in equipment). It doesn’t do any good to have new equipment if you don’t have work for it. Hopefully the economic tide will turn soon.”

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Twinkle Kisogawa bridge

An extradosed bridge employs a structure that is frequently described as a cross between a girder bridge and a cable-stayed bridge. The name comes from the French word extradossé, which is derived from the word extrados. Extrados is defined as the exterior curve of an arch.

This description is somewhat deceptive, since many cable-stayed bridges have some sort of box-girder deck. The difference is one of degrees.

A typical cable-stay bridge has a tower with a height above the deck at least half the span to the next support, since the cables are the vertical support and must come at a relatively high angle.

In an extradosed bridge, the deck is directly supported by resting on part of the tower, so that in close proximity to the tower the deck can act as a continuous beam. The cables from a lower tower intersect with the deck only further out, and at a lower angle, so that their tension acts more to compress the bridge deck horizontally than to support it vertically. Thus the cable stays act as prestressing cables for a concrete deck, whether made with I-beam girders or a box girder. The deck of an extradosed bridge can be thinner than that of a comparable span-beam bridge, but must be thicker than that of a conventional cable-stayed bridge of comparable span.
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Design of Highway Bridges An LRFD Approach

The up-to-date guide to applying theory and specifications to real-world highway bridge design. Design of Highway Bridges, Second Edition offers detailed coverage of engineering basics for the design of short- and medium-span bridges. Based on the American Association of State Highway and Transportation Officials (AASHTO) LRFD Bridge Design Specifications, it is an excellent engineering resource. This updated edition features:

• Expanded coverage of structural analysis, including axle and lane loads, along with new numerical analytic methods and approaches
• Dozens of worked problems, primarily in Customary U.S. units, that allow techniques to be applied to real-world problems and design specifications
• Revised AASHTO steel bridge design guidelines that reflect the simplified approach for plate girder bridges
• The latest information on concrete bridges, including new minimum reinforcement requirements, and unbonded tendon stress at ultimate and losses for prestressed concrete girders
• Information on key bridge types, selection principles, and aesthetic issues
• Problems and selected references for further study
• And more

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Gravel roads: Maintenance and Design Manual

There are over 1.6 million miles of unpaved roads (53% of all roads) in the United States.In some nations, the road network is predominantly unpaved and generally consists of gravel roads. This manual was developed with a major emphasis on the maintenance of gravel roads, including some basic design elements.

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Vehicle-Bridge Interaction Dynamics:With Applications To High-Speed Railways

The commercial operation of the bullet train in 1964 in Japan marked the beginning of a new era for high-speed railways. Because of the huge amount of kinetic energy carried at high speeds, a train may interact significantly with the bridge and even resonate with it under certain circumstances. Equally important is the riding comfort of the train cars, which relates closely to the maneuverability of the train during its passage over the bridge at high speeds.

Vehicle-Bridge Interaction Dynamics:

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Design Guide for Composite Highway Bridges

Composite construction, using a reinforced concrete slab on top of steel girders, is an economical and popular form of construction for highway bridges.

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AASHTO LRFD Bridge Design Specifications

This major step in improved bridge design and more accurate analysis is expected to lead to bridges exhibiting superior serviceability, enhanced long-term maintainability, and more uniform levels of safety. This edition includes newly updated foundation specifications, as well as updates throughout.

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