Bridges Construction

Bridge construction tends to involve huge projects that encompass the utilization of skills related to several engineering disciplines including geology, civil, electrical, mechanical, and computer sciences. Therefore, integrating the efforts of all involved must be meticulous.

Bridges

Post tensioning is ideally suited for pre-stressing long span girder at the site of construction, without the need of costly factory type installations like pre tensioning beds. Segmental construction is ideally suited for post tensioning work. In this method a number of segments can be pre-stressed resulting in an integrated structure.

Post tensioning bridge decks are generally adopted for longer span exceeding 20m. Bridge deck with precast post – tensioning girder of either T- type or Box – Type, in conjunction with a cast in situ slab are commonly adopted for spans exceeding 30m.

Continuity tendons are stressed to join adjacent cantilevers and resist positive moments from superimposed dead loads, creep redistribution, and live loads. In general, they contain,

• Internal tendons - Plastic duct or steel duct
• External tendons - Permanent or Replaceable with duct or ductless (epoxy coated strands)
• Extra - dosed tendons

The top cantilever post-tensioning counters these effects by inducing a compression stress of equal or greater magnitude at each cross section along the cantilever.

All spans were cast-in situ, except for the main span which was constructed using precast segmental method. Some of the types are,
Based on Geometry:
* Simple monocellular box girders
* Monocellular box girders with ribs or struts
* Double-cell box girders
* Composite multiple box girders

Based on Material:
* Concrete Box Girder
* Steel Box Girder
* Composite Concrete Box Girder

I-Girder Bridge is a bridge that utilizes girders as a means of supporting the deck. A bridge consists of three parts: the foundation (abutments and piers), the superstructure (girder, truss, or arch), and the deck.

I-Girder Bridge is very likely the most commonly built and utilized bridge in the world. Its basic design, in the most simplified form, can be compared to a log ranging from one side to the other across a river or creek.

During construction of the stations, poured concrete or precast panels are used to form the various levels and internal structures. Scope includes installation of tendons, stressing of tendons, erection of segments and grouting of tendons. Placing, stressing & grouting of tendons is as similar as a procedure that is in other applications.