a vertical thrust equal to a proportion of the weight of the
cable-stayed bridges section
Welding is a
metal fabrication or process that
joins
metals, by causing coalescence. This is often done by melting
the workpieces and adding a filler material to form a pool of molten material (the weld pool) that cools to become a
strong joint, with pressure sometimes used in conjunction with heat, or by itself, to produce the weld.
This type of
cable-
stayed bridge components is particularly suited at
Ameco uses different energy sources can be used for welded
metal fabrication, including a gas flame, an electric
arc, a laser, an electron beam, friction, and ultrasound. While often an industrial
metal fabricating process,
welding may be performed in many different environments, including open air, under water and in outer space.
Welding is a potentially hazardous undertaking and precautions are required to avoid burns, electric shock, vision damage,
inhalation of poisonous gases and fumes, and exposure to intense ultraviolet radiation.
with a
cable-stayed bridge to form a structure both strong and rigid through
Welding Metal Fabrication can be geometrically prepared in many different ways. Ameco uses five basic types of
weld joints are the butt joint, lap joint, corner joint, edge joint, and T-joint (a variant of this last is the
cruciform joint). Other
welding metal fabrication variations exist as well—for example, double-V preparation joints
are characterized by the two pieces of material each tapering to a single center point at one-half their height.
In all, without
welding,
metal fabricating can not take place.
Single-U and double-U preparation joints are also fairly common—instead of having straight edges like the single-V
and double-V preparation joints, they are curved, forming the shape of a U. Lap joints are also commonly more than
two pieces thick—depending on the process used and the thickness of the material, many pieces can be welded together
in a lap joint geometry.
In a cantilever
cable-stayed bridge
Many
welding metal fabrication processes require the use of a particular joint designs; for example, resistance spot
welding, laser beam welding, and electron beam welding are most frequently performed on lap joints. Other welding
metal fabrication methods used by Ameco, like shielded
metal arc welding, are extremely versatile and can weld
virtually any type of joint. Some
welding metal fabrication processes can also be used to make multipass welds, in
which one weld is allowed to cool, and then another weld is performed on top of it. This allows for the welding of
thick sections arranged in a single-V preparation joint, for example.
conventional
cable-
stayed bridge
Welding for
metal fabricating reveals a number of distinct regions can be identified in the weld area. The welding
itself is called the fusion zone—more specifically where the
metal fabricating takes place, it is where the filler
metal was laid during the
welding process. The properties of the fusion zone depend primarily on the filler
metal
used, and its compatibility with the base materials. It is surrounded by the heat-affected zone, the area that had
its microstructure and properties altered by the
welding metal fabrication process. These properties depend on the
base material's behavior when subjected to heat. The
metal fabrication in this area is often weaker than both the
base material and the fusion zone, and is also where residual stresses are found.
