Flyover Formwork

NOVEMBER 2012

CASE STUDY OF BRIDGE FORMWORK

Introduction FORMWORK It is a structure which is usually temporary but can be whole or part permanent, it is used to contain poured concrete and other such materials to mould in into required dimensions and support until it is able to support itself.

Requirements of formwork  Strength  Rigidity  Less leakage  True to size  Smooth surface  Easy removal  Supports

ECONOMY IN FORMWORK 

Forms of regular sizes and shapes

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Allow reuse

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Design structural components to allow use of commercially available forms

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Clean and oil forms after use

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Pre-fabricate the forms on the ground

MATERIALS FOR FORMWORK 

Steel

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Timber

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Plywood

FORCES ON FORMWORK

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Dead load

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Live load

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Vertical loads

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Lateral pressure

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Lateral loads

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Special equipment loads

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Other loads

CASE STUDY ON GOTA FLYOVER

DETAILS OF FORMWORK

LAYOUT OF MIDDLE SPAN PEIR

J4

J3

50M

J2

J1 25M

J4

J3

FORMWORK ON MIDDLE SPAN

J2

J1

PRIMARY ISMB

SECONDARY ISMB

TRUSSEL

ARRANGEMENT OF PRIMARY BEAMS

OVERLAPPING OF ISMB

ARRANGEMENT OF TIE ROD

Tie rod are used to hold shuttering so that is does not collapse during concreting. It has two wooden blocks connected with a rod for tightening arrangement.

JACK

Jacks are used to provide flexible arrangement over the trussels so that it can be easily removed during deshuttering. During construction of pier wooden blocks are kept so that after concrete sets up, the wooden block is burnt so that formwork can be removed easily. Jacks should be strong enough to withstand the dead load of concrete so they are made of steel,

Formwork for RE-Walls

Precast RE-walls were constructed on site with the help of above formwork. Here mild steel formwork is used for construction. Both the approach roads were constructed using precast RE-walls.

SHUTTERING ON RE-WALLS

SHUTTERING

After erecting RE-walls cress barrier is constructed using ply shuttering and held with the help of tirods.

CASE STUDY ON FLYOVER NEAR ELLIS BRIDGE The floyover starts from ellis bridge crossroads and extends up to Gujarat college road. Due to heavy congestion of traffic at ellis bridge crossroads, need was felt to build a flyover that would help in reducing the traffic congestion and travel time which in turn would reduce traffic accidents. We observed mainly formwork erection of pier cap and bridge slab. During the visit at site, construction of pier was going on. The following are the main components of formwork for flyover 1. Steel Truss  The most used component in formwork.  It is made up using steel panels.  Dimension of each panel are 1.5’x1.5’  It is responsible for transferring the entire load to foundation.

2. CLAMPING OF STEEL SUPPORT USING I-SECTION AND BOLT Diameter of bolt is 12mm .

3. ERECTION OF STEEL SHUTTERS FOR PIER CAP  Steel Shutters are erected on the edge of pier.  The shutter assembly has holes on the edge which are to be fixed using bolts.

4. Connection between pier and steel shutter using bolts

5. SUPPORTING MECHANISM  Steel truss props are laid.  Over them, I sections are placed.  Adjustable rods are placed between I-sections and Steel Shutters

Formwork for Bridge Slab 1. Inverted N-TYPE truss used above the steel supporting member N-TYPE truss is placed above the supporting member.

2. I sections placed over N-TYPE  I sections transfer the load to N-type truss.  Over the I sections STEEL SHUTTERS are erected  Steel shutters have box sections behind them for support.  The final view after erection of steel shutters from below the bridge is as shown in picture.

 In case of curved portion of pier, above the I-section

 BOTTOM VIEW OF CURVED SURFACE

 ULTIMATE VIEW OF BRIDGE SLAB