Transportation, unloading and erection of the precast prestressed concrete girders shall be done under the direction of experienced engineer he should be present for all stages of girder loading, unloading and erection. We have divided all these process into 7 sections
This methodology describes a detailed procedure for the erection of PSC Girders. Minor changes to the methodology would be adopted to suit the site conditions.
2.SCOPE OF WORK:
The scope of this methodology covers Lifting, Transportation and Erection of PSC Girders for all Flyovers & Bridges.
The responsibilities of the entire operation shall be assigned to a Senior Officer of the company who shall take care as an In-charge regarding all
- A) Personnel to be deployed for smooth conducting work
- Section In charge-01 No’s
- Site Engineer/Site Supervisor-01 No’s
- Fore Man-01 No’s
- Segment man-02 No’s
- Rigman-04 No’s
- Kalasi-06 No’s
- Crane Operator-2 No’s
- Hydra Operator-2 No’s
- B) Personnel to be deployed for safety during work
- Officer Safety-01 No’s
- Supervisor Safety-01 No’s
- Marshal Man -02 No’s
5. MACHINERIES :
- Modular Trailers with capacity of 60 MT (2 Nos.).
- Tyre mounted 180 MT crane with Telescopic or Lattice Boom (2 Nos.)
- Tyre mounted mobile 80 MT service crane (1 Nos.)
- Pilot van (1 No.)
6.0 CONSTRUCTION METHODOLOGY
6.1 PREPARATION OF SITE AT ERECTION POINT:-
Following points to be ensured:-
- The site of erection and the approach to be leveled, dressed and rolled (if required) so that the machineries viz; cranes and trailers move and can be placed on s firm ground in correct position.
- Overhead obstruction (if any) to be removed.
- Adequate Area lighting to be provided for work at night.
- Proper and safe access to be arranged for supervisory staff to climb up to the top of Pier Cap to check correct alignment/ level of girder when erected.
- All lifting tackles viz; Slings, D- Shackle, U clamp ropes and temporary packing viz. wooden block etc. to be checked regarding the Quality/ Soundness and kept near site.
6.2 LOADING OF GIRDER AT CASTING YARD:-
Following points to be ensured:-
- The girders are to be loaded at the casting yard either by the help of Mobile Cranes.
- The site where the girders are to be loaded on to the trailer to be dressed leveled and rolled (if required) for smooth and safe movement of trailers and cranes.
- After girder is loaded on to the trailers, the same is to be securely tied at two ends (near support) so that the same doesn’t tilt during transportation.
- Girders to be loaded for erection are to be identified and checked carefully regarding length etc. so that there is no mistake regarding the sequence to erection.
- The engineer shall check the identification mark, length and finishing of girders before loading on to trailers.
- Lifting tackles viz; slings etc. to be checked and sleepers/ packing are to be kept in correct position before placing the girders on to the trailer.
6.3 ERECTION OF GIRDER:-
- Before starting erection work the positions of trailer and the cranes are to be ascertained carefully to ensure that during lifting, swinging and placing on to the pier cap is done smoothly.
- Before lifting the girders, the Radius and Angle of the crane booms to be checked to ascertain safe lifting capacity during erection.
- The outriggers of the cranes must have proper supports/ packing so that during lifting, swinging and placing the girder, cranes remain stable.
- Once the girder gets lifted from the trailer, it is to be moved out from the erection site so as to provide adequate space during erection.
- The girders thus being erected to be placed directly on the Neoprene Bearing (which are to be fixed prior to erection in correct position and level). In-case the girder cannot be placed directly on the bearing the same is to be placed on Pier Cap on wooden sleepers and shifted to correct location by changing the position of the cranes.
- Before removing the slings from the erected girders it is important to temporarily support the girders by the help of proper diagonal supports. When the second girder is erected in position immediate arrangement is to be made to tie two girders at the support and at the middle by proper tie member (i.e. Channels, Angles etc.).
- The position of the cranes is to be changed for erection at each girder suitably as required.
- Once all girders for one carriageway are lifted and placed in positions, cross diaphragm are to be cast so that temporary ties can be removed.
Safety during lifting, loading, transportation and erection is the most important and primary consideration of the entire operation. The following points need to be checked and ensured:-
- Capacity of cranes, trailers, lifting devices and packing (wooden blocks) to be ascertained before use.
- The approach for the cranes and trailers both at the loading and erection point must be leveled, dressed and rolled to ensure smooth and safe movement.
- During transportation/ movement of cranes all care to be taken to ensure smooth traffic flow on the highway.
- A Pilot van with flag/ batten light must escort the cranes and trailers during their movement.
- Safety officer along with traffic marshals must be available during the entire operation to ensure safety.
- All persons engaged must use P.P.Es viz. helmets, belts, gloves, shoes, jackets etc.