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Attempts have been made to increase the safety of bridges with pin and hanger assemblies by adding some form of redundancy to the assembly. Retrofits that add redundancy to pin and hanger assemblies include adding a "catcher's mitt"—a short steel beam attached to the bottom of the cantilevered girder that extends out beneath the suspended girder to "catch" the suspended girder should ...
A chair screw (also known as coach screw [16]) is a large (~6 in or 152 mm length, slightly under 1 in or 25 mm diameter) metal screw used to fix a chair (for bullhead rail), baseplate (for flat bottom rail) or to directly fasten a rail. Chair screws are screwed into a hole bored in the sleeper. [17]
Strut is normally made of sheet steel, with a zinc coating (), paint, epoxy, powder coat, or other finish.. Strut channel is also manufactured from stainless steel for use where rusting might become a problem (e.g., outdoors, facilities with corrosive materials), from aluminium alloy when weight is an issue or from fiberglass for very corrosive environments.
Head: round flat metal piece formed at the top of the nail; for increased holding power; Helix: the nail has a square shank that has been twisted, making it very difficult to pull out; often used in decking so they are usually galvanized; sometimes called decking nails; Length: distance from the bottom of the head to the point of a nail
Tapcon screws are a popular anchor that stands for self tapping (self threading) concrete screw. Larger diameter screws are referred to as LDT's. This type of fastener requires a pre-drilled hole—using a Tapcon drillbit—and are then screwed into the hole using a standard hex or phillips bit. These screws are often blue, white, or stainless ...
In an underspanned suspension bridge, also called under-deck cable-stayed bridge, [21] the main cables hang entirely below the bridge deck, but are still anchored into the ground in a similar way to the conventional type. Very few bridges of this nature have been built, as the deck is inherently less stable than when suspended below the cables.
In a simple suspension bridge the deck lies on the main cables In a suspended deck bridge the deck is carried below the main cables by vertical "suspenders" Comparison of a catenary (black dotted curve) and a parabola (red solid curve) with the same span and sag. The catenary represents the profile of a simple suspension bridge, or the cable of ...
Screw foundations first appeared in the 1800s as pile foundations for lighthouses, [4] and were extensively used for piers in harbours. Between the 1850s through 1890s, more than 100 screw-pile lighthouses were erected on the east coast of the United States using screw piles. Made originally from cast or wrought iron, they had limited bearing ...