The following point has been taken as a safety consideration during girder casting and lunching operation:
- Gaps should be maintained between two lifting Strands to make all-round
- concrete bonding is available. The position of lifting and supporting points should be specified
- Forms shall be of sufficient thickness, with adequate external bracing, and shall be stiffened and adequately anchored to withstand the forces due to placement and vibration of concrete.
- Shutter Vibrator should be used in sufficient numbers.
- All joints of formwork shall be leakproof.
- The correct locations and orientation is to be maintained.
- The girders shall not be moved from the casting location until the stipulated strength is attained.
- The concrete shall have attained a minimum compressive strength of 20 MPa at the time of removal of side shutters.
- Curing of concrete may be achieved through water or steam in the initial curing period, followed by water curing.
- It shall be ensured that the entire length of each strand between the grips is free of any defects. A diamond bit saw or grinder with a cutting wheel shall be used to cut the strands.
- Strands and un-tensioned reinforcement shall be so arranged that the un-tensioned reinforcement and those strands which are required to be extended into the adjoining cast-in-situ concrete in the end diaphragm locations, do not get affected during cutting operation.
- Debonding of strands, wherever required, shall be carried out using HDPE debonding tubes. PVC tubes shall not be permitted for this purpose.
- After Pretension-ing the Strands and before concreting a recheck shall be made to ensure that the debonding tube is placed at the intended locations. Both ends of debonding tubes shall be effectively sealed against the ingress of any cement slurry using epoxy putty.
- The position of lifting and supporting points should be specified. The design should take account of the effect of lifting and placing on to supports.
- Adequate side supports or wooden packing on either side of the bearing should be provided to ensure true verticality before connecting with diaphragms.