Horizontally Curved Steel Box Girder Bridge Long Span Steel Girder Bridge in Railway

History

Girder bridges have existed for millennia in a variety of forms depending on resources available. The oldest types of bridges are the beam, arch and swing bridges, and they are still built today. These types of bridges have been built by human beings since ancient times, with the initial design being much simpler than what we enjoy today. As technology advanced the methods were improved and were based on the utilization and manipulation of rock, stone, mortar and other materials that would serve to be stronger and longer.

In ancient Rome, the techniques for building bridges included the driving of wooden poles to serve as the bridge columns and then filling the column space with various construction materials. The bridges constructed by Romans were at the time basic but very dependable and strong while serving a very important purpose in social life.

As the Industrial Revolution came and went, new materials with improved physical properties were utilized; and wrought iron was replaced with steel due to steel's greater strength and larger application potential.

Design

All bridges consist of two main parts: the substructure, and the superstructure. The superstructure is everything from the bearing pads, up - it is what supports the loads and is the most visible part of the bridge. The substructure is the foundation, transfers loads from the superstructure to the ground. Both must work together to create a strong, long-lasting bridge.

Configuration of a multi-girder bridge

In multi-girder construction, a number of similarly sized longitudinal plate girders are arranged at uniform spacing across the width of the bridge, as shown in the typical cross section below. The deck slab spans transversely between the longitudinal girders and cantilevers transversely outside the outer girders. The girders are braced together at supports and at some intermediate positions. Composite action between the reinforced concrete deck slab and the longitudinal girders is achieved by means of shear connectors welded on the top flanges of the steel girders.

The arrangement shown in the image below is common where permanent formwork is used and shows four girders of equal depth and with a slab surface that follows the camber of the road. A footway/verge is provided either side of a 2-lane single carriageway and parapets/restraint barriers are mounted on the edge beams.

Features
1) Cost saving and transportation convenient, customer design available.
2) The main beam and column are qualified steel.
3) The steel structure makes the house resisting heavy wind of 140km/h and 8 grade earthquake.
4) Good ability to assemble and disassemble for several times without damage.
5) Widly used in construction site,office building,dormitory etc.
6) Environmental protection effect is good. Steel structure housing construction greatly reduces the sand, stone, the dosage of the ash, used materials mainly green, recyclable or degradation materials, building dismantled, most of the material can be recycled or degradation, won't cause much rubbish.

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