STRUCTURAL STRENGTHENING OF CONCRETE WALL WITH FIBER REINFORCED POLYMER COMPOSITE MATERIAL AT VITAL NUCLEAR POWER PLANT FACILITY FOR WITHSTANDING 360 MPH TORNADO WINDS

MISSION CRITICAL PROJECT No. 7:

• Bunker type superstructure for storing critical emergency equipment for manually shutting down the nuclear reactor during a seismic or flood beyond design basis event.
• The structure must be capable to withstand a 360 mph tornado wind, and missiles impact.
• All existing reinforced concrete walls are 24” thick except for one that it is 18” thick.
• The objective of this critical mission was to increase the structural capacity of the 18” wall in order to be able to withstand the loads generated by the 360 mph tornado winds and missile impact.

PROPOSED SOLUTION:

Reinforced 18” thick concrete wall, bending structural strength capability increased with FRP (i.e. Epoxy & Carbon Fiber).

INPUT SUMMARY & REQUIREMENTS:

1. Concrete compressive strength = 3 ksi
2. Density of reinforced concrete = 150 lb/FT
3. Rebar yield strength = 60 ksi
4. Tornado wind load = 360 mph
5. Required to withstand horizontal missile 1: 4” x 12” x 12’ wood plank Missile speed = 300 mph  Missile weight = 180 lb
6. Required to withstand horizontal missile 2: automobile Missile speed = 17 mph Missile weight = 4,000 lbs
7. 18” thick wall’s original bending capacity = 164 kip-in/ft
8. The demand bending moment is 540 kip-in/ft for horizontal axis, and 409 kip-in/ft for vertical axis. Final FRP solution (i.e. Epoxy and Carbon Fiber composite system):

FINAL FRP SOLUTION (I.E. EPOXY AND CARBON FIBER COMPOSITE SYSTEM):

9. 18” new design bending capacity = 724 kip-in/ft about the vert & hor directions, after FRP composite system is applied at the wall’s inside face.
10. 18” core wall only required two (2) bi-directional plies of frp composite system to increase the bending capacity to 724 kip-in/ft. Each ply was 0.05” thick.
11. Total unit weight of two bi-directional plies = 2.5 lb/yard . Thus, total composite weight is negligible.

CONCLUSION:

This is an example of an excellent cost-effective technical solution project for increasing the structural capacity of a wall using advanced engineered FRP composite systems. The useful life of this composite application will outlast the remaining useful life of the facility of 25 years.