A composite steel box girder for high-speed railway and its construction method

Abstract

The invention discloses a combined steel box girder for high-speed railways and a construction method thereof, belonging to the field of high speed railway bridges. A top flange plate of the steel box of the combined steel box girder is provided with a shearing resistance connecting member which connects the above concrete slabs with the top flange plate. At the same time, a steel base plate and a prefabricated prestressed concrete plate are combined to collectively act as the base plate of the combined steel box girder for jointly bearing stress. Concrete slabs on the top flange plate can be cast in situ or prefabricated. since the girder which is made of the steel box, the concrete top plate and the prestressed concrete plate inside the steel box can be assembled in site, which is convenient for transmission and hoisting and it is possible to build longer span simply supported girder bridges on land. Compared with present whole simple girders of the same span, the provided combined steel box girder has increased cross section rigidity of the steel box girder, the weight of girders is reduced and the span of girders is increased. The combined steel box girder of the invention has reasonable construction stress and is convenient to construct; technical support is provided for building longer span simply supported girder bridges on land.

Description

technical field [0001] The invention relates to a combined steel box girder for high-speed railways and a construction method thereof, belonging to the field of high-speed railway bridges. Background technique [0002] At present, in the field of high-speed railways, simply supported beam bridges mostly use T-shaped section beams or box-shaped section beams. The former is referred to as T-beam and the latter is referred to as box girder. Because the T-beam bridge composed of T-beams has small lateral stiffness, poor torsion resistance, and poor stability during installation, the on-site operation time is long, so it is not suitable for use with large spans. Simply supported girder bridges with longer spans generally use box girders. [0003] Box girders include concrete box girders, steel box girders and composite steel box girders. When the span is large, the weight of the concrete box girder is very heavy, which brings difficulty to pouring or erection. For example, a 32...

AI Technical Summary

Problems solved by technology

If prestress is applied to the concrete after pouring, due to the existence of the steel floor, only part of the applied prestress acts on the concrete slab, and as the concrete shrinks and creeps, the prestress in the concrete will gradually decrease, which is an inefficient method, and it is still possible to use cracking under load

Another solution is to use a steel box as the bottom plate of the steel box girder, pour concrete or mortar into the interior, and then apply prestress. This is a good method and can meet engineering applications, but there are still the following disadvantages: Most of it is "consumed" on the steel box, and the steel box has a strong tensile capacity, so this part of the prestress is not needed; the concrete or mortar in the steel box still has problems of shrinkage and creep, and the internal prestress will be Reduced during use; if the concrete or mortar in the steel box is poured before erection, the hoisting weight will increase; if the concrete or mortar in the bottom plate is poured after the steel box is installed in place, and then prestressed, the construction progress will be affected ;Because the bottom plate of the steel box is used as a template for pouring concrete or mortar, its width cannot be large, and a composite beam cannot meet the needs of the entire bridge. It can only be assembled with multiple beams in the horizontal direction, which will Complicates field work and increases work time

Images