How The Railway T-Beam Girder Is Made
The Standard Railway Project will among others involve the construction of a railway from Mombassa to Nairobi. Mombassa being in a costal area provides a gradient challenge for the railway engineers as it climbs to Nairobi.
The Standard Railway Project will among others involve the construction of a railway from Mombassa to Nairobi. Mombassa being in a costal area provides a gradient challenge for the railway engineers as it climbs to Nairobi. To counter this challenges bridges will be constructed at strategic points. The Tsavo National Park is a sensitive ecological system and a migratory corridor for animals. Bridges and animal passages shall also be constructed. All this shall requite the T-Beam beam held up by pillars for the railway to pass above.
A girder is basically a support beam that is used in construction. Its the most common type used in construction of bridges. The T-Concept allows for longer spans and low maintenance costs. In some documentation its called a beam to mean the same thing. The T-Beam Girder, the top series as a compression member in resisting compression stress while the web of the beam below serves to resist the shear stress. For the SGR, Reinforced Concrete steel beam are used.
At the Section 7 construction site, the T-Beam production process involves 15 steps which last upto 6 hours. Currently they are doing 2 beams per day. The beams are precast then hoisted to storage for further controlled drying awaiting transportation to the installation site.
Template Cleaning and Oiling
To prevent the concrete from sticking to the beam, the mould has to be oiled thoroughly and left to dry for some few hours before the concrete is poured.
Tie Plate Reinforced and Beam Plate Steel
The second step involve the addition of the reinforce steel onto the base plate, This is the largest step and also involves the largest workforce. The steel reinforcement steel is assembled. Steel fixers and welders are involved in this step. Steel increases the strength of the T-Beam
End Plate Installation
After the reinforced steel has been added to the mould, the end to end steel plates are locked in to provide a point of entry for the inner stress steel cables.
Black Tube Insertion
A series of black rubber tubes are inserted into the steel frame. Once dried these black tubes are with drawn leaving a hole for the inner tension cabling.
On each side of the T-beam, 7 columns are created by adding for steel for each column. In each beam there are 14 columns in total.
Assemble Lateral Template
At this stage the side templates are installed to form a complete set ready pouting of concrete. Top assembles are also added to prevent the mould from falling apart when vibrating the concrete.
This is the stage where wet concrete is poured continuously for 3 hours into the mould. On each pour super vibrators are turned on to ensure that it sets in and eliminating the formation of air bubles.
Drawing of Black Tubing
After a few hours after the pouring of concrete, the black tubes are withdrawn before the concrete has fully dried. This leaves hollow openings through the beam.
Template Removal and Beam Modification
After 8 hours the T-Beam is ready for mould removing. The mould does not come of easily so a careful process has to be used. After removal of the mould, the beam is smoothed if small air hold are visible.
Once the beam has been declared finished, it is hoisted by the gantry cranes to the storage area where it undergoes controlled drying. The whole process starts again.