steel reinforced concrete. The reason is because they are based on different approaches.

For the case of the CFRP grid reinforced concrete a method that can produce ductility

factors in the spirit of the ductility factors for steel reinforced concrete is needed. Such a

method will be a measure of the plastic deformations of the FRP reinforced structure that

take place due to concrete confinement.

 500

 400

 S300

 S200

 100 -+- Control
 -e- Tube

 0 0.0002 0.0004 0.0006 0.0008 0.001
 Curvature (rads/in)

Figure 4-25. Experimental M-D curves for both beams

 The following method, to determine ductility factors for CFRP grid reinforced

concrete is recommended. Because the mode of failure for the grid reinforced structures

is concrete crushing and not yielding of steel there is a need for a new parameter that will

replace yield displacement or curvature in the ductility factors. This need is especially

evident in the case of concrete structures with FRP flexural reinforcement. The new

parameter to replace yield displacement or curvature is named displacement or curvature

at crushing (6c or Oc). This follows the same logic as the yield displacement or curvature.

For the yield displacement or curvature first yield is used to define the displacement or

ductility while for the CFRP grid reinforced structures first crushing is used. First

crushing is defined as the point at which the load causes the cover concrete to spall which

is assumed to happen at a concrete compressive strain equal to 0.003 (ACI Committee