30-08-2014, 03:54 PM
India’s first ‘Signature Bridge’, being constructed across the Yamuna River at Wazirabad, promises to be a great attraction of New Delhi. An ambitious project for the Delhi Tourism & Transport Development Corporation, the cable-stayed bridge will link National Highway number one near existing T-point at Wazirabad on Western Bank and Marginal Bund Road at Khajuri Khas on Eastern bank of Yamuna River, thus, connecting North Delhi with East Delhi. Considering The tremendous rise in population in the Trans Yamuna area, there is a pressing demand for an East-West corridor on the river.
About The Company-
Gammon India Ltd. Is a civil engineering construction company
Undertaking infrastructure projects, transportation projects.
Gammon India is not only one of the largest civil engineering companies in india but can also lay claim to having built the maximum number of bridges in the whole of the commonwealth.
For nearly a century Gammon has been undertaking and executing
The toughest engineering and construction projects. From the
Gateway of India to India’s First indigenously designed fast breeder
Reactor, Gammon has become one of the world’s leading construction companies, diversified in to areas including Infrastructure management, transmission lines and power sectors.
PROJECT INFORMATION-
India’s first ‘Signature Bridge’, being constructed across the Yamuna
River at Wazirabad, promises to be a great attraction of New Delhi.
An ambitious project for the Delhi Tourism & Transport Development
Corporation, the cable-stayed bridge will link National Highway number one near existing T-point at Wazirabad on Western Bank and
Marginal Bund Road at Khajuri Khas on Eastern bank of Yamuna River, thus, connecting North Delhi with East Delhi. Considering
The tremendous rise in population in the Trans Yamuna area, there is a pressing demand for an East-West corridor on the river.
Brief Description of Project:-
DIAPHRAGM:- Diaphragm is a member that resists lateral forces and transfers load to support. Some of the diaphragms are post tensioned and some contain normal reinforcement. It is needed for lateral stability during erection and for resisting and transferring earthquake loads. On this site, diaphragm segment is cast-in-situ on the pier to transfer the load of the superstructure to the piers. This bridge is not provided with a cast-in-situ diaphragm. A constant 1500mm rectangular gap shall be left in between tranverse/radial axis of pier adjacent segment. Pier diaphragm is one of the most difficult cast-in-situ structures on this site. Diaphragm’s reinforcement and shuttering schedule is very difficult to build on site, so it consumes a lot of time and attention of engineers on site.
FUNCTIONS OF DIAPHRAGM:- The main function of diaphragms is to provide stiffening effect to deck slab incase bridge webs are not situated directly on top of bearings. Therefore, diaphragm may not be necessary incase bridge bearings are placed directly under the webs because loads in bridge decks can be directly transferred to the bearings. On the other hand, diaphragms also help to improve the load-sharing characteristics of bridges. In fact, diaphragms also contribute to the provision of torsional restraint to the bridge deck.
REINFORCEMENT IN DIAPHRAGM:- All pier diaphragm concrete shall be 4000 PSI,610 cement concrete.
All reinforcement shown in these details shall be coated.
Labourer may use expanded polystyrene filler or a removable form to form the bottom of the pier diaphragm.
Place expanded polystyrene filler under the bottom flange at the edge of the shear key.
Prior to placing pier diaphragm concrete, line all surfaces of the shear key with closed cell foam.
Reinforcement used is about 10tons.
SELF COMPACTING CONCRETE IN DIAPHRAGM:- After the shuttering and reinforcement, final step is concreting.
Concrete used in pier diaphragm is Self Compacting Concrete.
Grade of concrete used here is M60.
Around 30m3 of self compacting concrete is consumed by a diaphragm.
Usually we need a needle vibrator to place the concrete but here as we are using self compacting concrete which automatically drives to all the corners so we don’t need any vibrator here.
Concrete is pumped to the diaphragm by concrete pumping machine
STRESSING:- After the alignment of segments between the two piers there is insertion of cables in the segments. Segments consist of holes having HDPE pipes through which cables is inserted.
Segment consist of 8 holes and each hole having 19 cables in it.
Then the stretching of wires is done from both the ends with the help of hydraulic jack and the pressure maintained for the stretching of wires is 515-520 Kg/cm2.
STRESSING OPERATION:- Applying initial pressure of 50kg/cm2 at stressing ends. Travel of jack piston with reference to the jack body is measured with the help of a scale.
Increase the pressure to 100kg/cm2 and measure the elongation. Continue stressing to required pressure at intervals of 50kg/cm2 and note down the ram movement. All these operation carried out simultaneously at both the end.
After reaching desired pressure and required elongation wedges are being locked by blocking operation. Release the jack to 50kg/cm2 and measure slip.
Release the jack and mount it to next station
WATER TESTING:- After the work of stretching of wires water testing of pipes is done. Water testing is done for the purpose of checking leakage in pipes. Pressure maintained in water testing of pipes in
3Kg/cm2. If there is any leakage in pipes then we will paste it by using material Randroplug paste.
GROUTING:- The purpose of Grouting the cable is to provide permanent protection to the post tensioned steel against corrosion and develop bond between pre stressing steel and surrounding concrete. The grout ensures encasement of steel for corrosion protection and fills the duct space to prevent water air passage.
Grouting should proceed as soon as possible after installation and stressing of the tendons. Depending upon environmental conditions , temporary protection may be necessary and temporary protection of the ends of the stands will be necessary
GROUTING OPERATION:- Grouting is done for different length of cables like 8m, 12m, 78m, 90m, the purposed time for completing the grouting for 8m length is 5minute and the flow of material is maintained about of 3kg/cm2. Material used for grouting consist of water, cement and ceebex 100
For 1m grouting 11kg paste is used
For 8m = 11x8 = 88kg
No. of bags of cement required for 8m = 88/50 = 1.03bag
BATCHING PLANT:- A concrete plant, also known as batch plant, is a device that combines various ingredients to form concrete. Some of these inputs includes Sand, Water, Aggregate(rocks, gravelsetc), Fly Ash, Potash and Cement. The centre of the concrete batching plant is the mixer. There are three type of mixer: Tilt, Pan and Twin shaft mixer. The twin shaft mixer can ensure an even mixture of concrete and large output. The conveyors are automatically operated with five sensors and weighing scale with which the conveyor can be stopped at any time if some errorsoccurred. The concrete output is approximately 30m3/hrof 3 compacted concrete for a batch size of 0.5m3. the plant design fully meets the
Requirements as a mixing plant for ready mix concrete or as a plant at building site.