Beam bridges

Figure 1.4 Size maximization (a) truss bridge, (b) beam bridge.

Reinforced concrete Concrete containing a network of reinforcing steel bars to make a composite material that is strong in tension as well as in compression. Smaller volumes of material can therefore be used to make beams, bridge spans, etc, compared vith unreinforced concrete, brick or masonry. 

Beam Bridge Simplest type of bridge consisting of two or more supports holding up a beam ranges from a complex structure to a plank of wood. 

Truss. A truss bridge is popular because it requires a relatively small amount of construction material to carry a heavy load. It works like a beam bridge, carrying loads by bending and causing compression and tension in the vertical and diagonal supports. 

Cantilever. Cantilevered means something that projects outward and is supported at only one end (similar to a diving board). This type of bridge is generally made with three spans with the outside spans supported on the shore and the middle span supported by the outside spans. This is a type of beam bridge that uses tension in the lower spans and compression in the upper span to carry a load. 

Key words filament winding, hybrid beams, bridge decks, concrete, confinement. 

It has been found that the contrast in film density caused by very small local variations in mass density of the concrete is considerable, e g. S D = 0.12 for a 6 mm diameter hole in a 250 mm thick concrete beam. The image quality provided by fine-grained films (Agfa Gaevert D7) was sufficient to distinguish the thin walls of a pre-stressing duct in a 750 mm thick concrete bridge slab. 

A number of pool, also called swimming pool, reactors have been built at educational institutions and research laboratories. The core in these reactors is located at the bottom of a large pool of water, 6 m deep, suspended from a bridge. The water serves as moderator, coolant, and shield. An example is the Lord nuclear reactor at the University of Michigan, started in 1957. The core is composed of fuel elements, each having 18 aluminum-clad plates of 20% enriched uranium. It operates at 2 MW, giving a thermal flux of 3 x 10 (cm -s). The reactor operates almost continuously, using a variety of beam tubes, for research purposes. 

Typical diameters are up to 150 ft. and machines have operating torques to 750,000 fir-Lbs. The Bridge - or Beam or Truss - spans the diameter of the tank and supports the drive and rake mechanisms. The underflow is removed from the discharge cone at the bottom center. 

A bolometer is essentially a thin blackened platinum strip in an evacuated glass vessel with a window transparent to the infrared rays it is connected as one arm of a Wheatstone bridge, and any radiation absorbed raises the temperature of the strip and changes its resistance. Two identical elements are usually placed in the opposite arms of a bridge one of the elements is in the path of the infrared beam and the other compensates for variations in ambient temperature. Both the above receptors give a very small direct current, which may be amplified by special methods to drive a recorder. 

The advantage of this approach is not only the free choice of surface stractures which can be created, the material contrast which can be realized by the combination of chemical lithography and amplification with SIP, but also the potential to bridge the gap in structural feature sizes ranging from the microscopic to the nano-scopic scale. Since the feature sizes reported are still limited to the features of the mask used, direct writing with a focused e-beam should result in patterned polymer brushes of features matching the size of the immobilized macromolecule. 

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