Fundamentals of Road Bridge Construction

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Learn how to Construct Road Bridges

See step by step guidelines & procedure.

bridge is a physical structure built to cover a physical obstacle such as water bodies, roads, or rail without blocking the way underneath. It is constructed to provide passage over the obstacle, which is something difficult or impossible to cross.

One such bridge is a road bridge to overcome the difficulties faced by the commuters due to huge traffic jams. So, let us understand the construction procedure of such bridges.

Two drawings are very important for any construction of the bridge.

  1. Lay out Plan
  2. Structural Drawing

Step 1

Layout Plan: – Layout is an arrangement, plan or design and it helps to get marking onsite for boring.

Structural Drawing: – It is very important because all the reinforcement details are available in this drawing which tells us about the depth of the Pile and based on the depth, the boring hole can be possible.

Structural Drawing of Bridge Constructions

Why Structural Drawing is important in Bridges?

It is important because all the reinforcement details are available inside the pile which tell us the Size (diameter) of the reinforcement cadge to be placed inside the borehole.

Step 2:

How can we do boring on Construction Surface?

Boring can be possible with the support of the Auger Boring Machine. The structural drawing gives the information about (Size) diameter/s.

Auger Boring Machine
Solid Casing Work

During the boring, inside the pile, place solid casing which helps to remove the damage of the boring hole from the hard particle (Stone, Rock) which comes from the hole.

Also Read: What is Soil Testing and how is it done for Bridges, Buildings, and Dams?

Step 3:

How to Convert Loose Soil into Hard Soil Inside the Boring Hole?

It is a major point to convert loose soil into hard soil which stops damage to boring holes. Ref below image wherein we can see some liquid is poured inside the boring hole with the support of pipe and this liquid is called bentonite polymer mix. This is an admixture to convert loose soil into hard soil and prevent damage to boring holes.

Bentonite Polymer Mix Liquid at the Bottom of Solid Casing
After Bentonite, place a solid particle in the bottom side of the pile hole
with the help of a bucket.

Step 4:

Why & How to insert Steel Casing inside the Pile?

With the support of a mechanical hydraulic crane, place steel casing inside the pile because manually it is not possible to do.  Steel casing is important because concrete that is put inside the boring hole will place in the proper way.

After steel casing: Insert reinforcement cadge inside the boring hole as per the structural design, after that put concrete inside the hole with the help of a concrete funnel tube.

Inserting reinforcement cadge into borehole
Fig. 1: Developing Reinforcement Cadge
Fig. 2: Developing Reinforcement Cadge

You have to do concrete pouring inside the hole slowly otherwise it will damage steel cadge or boring hole.

Step 5:

Pier & Super Structure

What is Pile Chipping & Pile Capping?

Pile chipping: Itis the extra pile above the cut-off level, which is provided for good and sound concrete. The main purpose of chipping is to remove the surplus slushy concrete over the cut-off level.  It can do in both ways – manually or mechanically.

Pile Capping: Very important part of the bridge construction. It is just above the cut-off level, we do pile capping because whatever load are coming from the bridge, will not go directly to the pile.

So, we can say foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics to support them.

What is Pier & Super Structure and why do we do it?

Super Structure

Pier: It is a vertical structure as per the structural design connected with the superstructure.

Super Structure: A superstructure is a structure that is directly connected with a pier where traffic will move. Two types of girders are available for construction are:

Precast Girder: Precast Bridge Girders are a dominant structural component used to support bridge decks and traffic loads for short to medium span bridges. They provide a low-maintenance and cost-effective solution.

Precast Girder

Casting C.2 GirderAs per the structural design, concert pouring is done on-site.

Casting C.2 Girder

What is the role of sonic logic measurement test in pile?

It is an important test as it helps to get information that the concrete which we are putting inside the pile is placing in a proper way or not. In the Sonic test, the top of the pile is tapped with a lightweight plastic hammer and the reflected waves are recorded by suitable equipment.

Sonic Logic Measurement Test
Sonic Logic Measurement Test

Equipment for Testing

Impact Echo cross-hole-sonic-logger-champ Pile_Driving_Analyzer Shaft Quantitative Inspection Device (SQUID)

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