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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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Theory and Design of Bridges

Covers current design techniques for both allowable stress and new load and resistance factor design (LRFD) approaches recommended by the forthcoming American Association of State Highway and Transportation Officials draft specifications. Addresses the need for repair or replacement of 225,000 U.S. highway bridges as well as the need for 70,000 new bridges in the next 15 years.
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This textbook is intended for studies in structural dynamics or wind engineering, with special focus on the stochastic theory of wind induced dynamic response calculations for slender bridges or other line- like civil engineering type of structures. It contains the background assumptions and hypothesis as well as the development of the computational theory that is necessary for the prediction of wind induced fluctuating displacements and cross sectional forces.

Theory of Bridge Aerodynamics

 The book contains detailed and complete examples of relevant cases that are useful for the understanding and the practical application of the theory. The text is at an advanced level in the sense that it requires some knowledge of basic structural dynamics, particularly of solution procedures in a modal format.

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Taking a fresh, holistic approach to the topic of architectural technology, this indispensable book looks at the ‘why’ as well as the ‘how’ of building science, providing a comprehensive, clear and concise introduction to the subject.

Building Science for Architects

The demands faced by architects in their training and education are constantly changing. Written by two practicing architects who teach building technology and design, this text ensures that the reader is given the full picture of the discipline, as it integrates technical material with design sensibilities.

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Setting Up the Experiment

Researchers conducted approximately 700 tests at the TFHRC Hydraulics Laboratory, with the physical modeling for the culvert study occurring in two phases. The first set of experiments optimized the bevel edge of the wingwalls and top edge using two-dimensional particle image velocimetry (PIV) in a 2.75-meter (9-foot)-long and 0.46-meter (1.5-foot)-wide flume, an artificial channel for measuring water flow. This technology uses a laser and particles of silver-coated and hollow glass spheres to make the flow visible. Cameras are used to measure instantaneous velocity vectors in a flow field.

The researchers tested several bevel edge conditions, including straight top bevels (square edge), beveled edge (45 degree bevel), and radius top bevels. The criterion they used to determine the best bevel performance was the contracted distance outside the viscous boundary layer, or the effective flow depth at the vena contracta (where the flow depth is lowest inside the barrel section). The researchers used integrated streamlines, which indicate the speed and direction of flow, to visualize the contracted area (the area where water flow narrows from a wider flow) inside the culvert.
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Recession deepening for contractors

Research from the Civil Engineers Contractors Association (CECA) has shown the recession to be deepening, with tender prices falling off a cliff, opening the door to a ‘double-dip’ recession.

While the April survey showed workloads deteriorating, but at a slower pace, the figures for July showed a renewed plunge.

This is the fifth successive quarter of contraction, and could indicate a double-dip recession, where the cycle of recession to recovery is hit by further weakness in the economy.

Forward order books have been in decline for more than a year, and 70% of the sample recorded lower order books than a year ago.

Tender prices began to decline in January this year for both new and repair and maintenance work. This trend has since become established and the July survey shows accelerating downward pressure on tender prices for both types of work.

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