The document provides design details for reinforcement around prestressing cable anchor blisters, including calculations for the required areas of bursting, linking, anti-spalling, and tie back reinforcement. Bursting reinforcement of 5 turns of 10mm spiral steel around each anchorage was determined to be sufficient based on calculated bursting force values. Linking duct reinforcement of 12mm diameter bars at 401.6mm2 was also sufficient based on calculated values from jacking force and duct radius.

1. 300 mm
200 mm
2ypo = Length of the side of Prestressing Anchor = 100 mm
2yo = Length of the side of Loaded area
Fbst = Bursting Force
Pk = Jacking Force = 1160 kN
Vertical Lateral Vertical Lateral Vertical Lateral
1 400 600 0.25 0.166667 0.23 0.23
Area of Bursting Reinforcement, A = Fbst/0.87fy
DESIGN OF ANCHOR BLISTER
600 mm
400 mm
Prism Dimensions ypo/yo Fbst/Pk
Cable No.
Prestressing
Cable

2. Bursting Reinforcement Requirement is as follows,
Vertically Laterally
1 738.9558 738.9558
Providing 5 turn spiral 10 mm dia round each anchorage over a length of 600 mm
resulting an area of 785.4 mm² ; Hence OK
Area of Links Tying Curved Duct, A = Pk/(R*0.87fy)
Radius of Curvature of Duct, R = 2.00m
Required Area of Link Reinforcement, A = 1.606426 mm²/mm considering
= 401.6064 mm² ; 12mm dia
Provided 12mm dia
Area of Anti Spalling Reinforcement, A = 0.04*Pk/0.87fy
Required Area of Spalling Reinforcement, A = 128.51406 mm²
U-bar at
Area of Tie Back Reinforcement, A = 0.5*Pk/0.87fy
Required Area of Tie Back Reinforcement, A = 1606.4257 mm²
;use 16mm dia Rebar at 125mm C/C
200mm C/C both way
Cable No.
Area of Rebar (mm²)
250mm C/C
at 250mm C/C
at 281mm C/C
;use 8mm dia U-bar at 391mm C/C
Provide 8mm dia