Launching gantry
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A Launching gantry is an item of bridge construction equipment. It is used to install precast girders in highway and high speed railway bridge construction projects. There are three kinds of launching gantries.
Honeycomb girder
The main girder is of welded plates in isoceles triangle section. Regular hexagonal honeycomb holes are cut in the inclined web plate for air currents to pass through. This reduces wind impact.[1] Welded plate by plate,if there is a mistake welding occasionally, the welding surface will not lose stability easily. Since the honeycomb girder launching gantry was created in 1999,（ZZHZ） it is found that its applicable lifting weight is from 5t to 300t. Nowadays it is used in highway bridge construction projects
Truss girder
The main girder is of welded steel poles. Point to point welding (steel poles to pole welding)has a high demand on welding technology With small self weight and large deflection, the truss girder launching gantry is suitable for highway bridge construction projects
Box girder
The main girder is of welded plate. This type is usually used in high speed railway bridge construction projects.[2]