SP Clamp Method
The Steel Pipe (SP) Clamp method is a slab replacement on a simple span composite prestressed concrete (PC) main girder bridge to retain the existing load capacity by using a precast PC slab.
Conventional slab replacement work, in which existing slabs are cut by waterjets and new slabs are constructed by in situ concrete casting, has issues of a long construction period.
After cutting the upper side of an existing rebar stirrup on a main PC girder, a crimped steel pipe is installed at the end of the rebar. This pipe has the same load capacity as the rebar stirrup. In addition, by extending the existing rebar stirrup with the crimped steel pipe at the box-out of the PC slab, the necessary load capacity against yawing of the main girder web can be maintained.
Existing slab
Example of slab removal
Replacing slab
Features
- By using the existing PC main girders and a precast PC slab, the SP clamp method realizes faster construction while maintaining the existing load capacity.
- The wire saw cutting method can be applied at the same time when the existing slab is removed from the PC main girders. This can reduce the construction period.
- This method is assumed to cut the upper side of existing rebar stirrups on the PC main girder, which is likely to be corroded by anti-freezing agents. Doing this assures improved durability of the bridge.
Example of construction work
Crimping machine of steel pipe
Completion of crimping work
