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The most effective method of shear strengthening with FRP sheets is to wrap the entire cross section of
the beam with FRP. Typically, this is not feasible from a job site standpoint. The presence of monolithic slabs or other supported elements often precludes wrapping the sheet around the top of the section. One
option might be to drill holes through the slab and wrap strips or bands of FRP around the section. However, this method is often too complicated and costly.
a. FRP wrapped entirely around the beam: in this case Carbopree Sheet HM 300 in the specification is suggested;
b. FRP "U" wrap mechanically anchored with Carbopree Rods: in this case Carbopree Sheet HS 300 in the specification is suggested;
c. FRP "U" wrap mechanically anchored with bolted steel L profile: in this case Carbopree Sheet HS 300 in the specification is suggested;
d. FRP "U" continuous wrap: in this case Carbopree Sheet HS 300 in
the specification is suggested;
e. FRP "U" wrap placed in strips: in this case Carbopree Sheet HS 300 in
the specification is suggested;s suggested;
f. FRP 45 wrap: in this case Carbopree Sheet HS 300 in the specification is suggested;
g. FRP 0/90 wrap: in this case Carbopree Sheet HS 300 in
the specification is suggested;
The most common method of shear strengthening is to wrap the sides and bottom of the section. This method, referred to
as a "U" wrap, is typically feasible and is fairly effective in increasing the section's shear strength. The use of the "U" wrap is, however, only highly effective in positive moment regions. In
negative moment regions, shear cracking initiates from the top of the section near the slab. Due to its location below the slab, the FRP may not be able to control the initiation of these cracks. Once these cracks
open, there is the potential for the crack to drive through section without any reinforcing effect from the FRP.
The transverse FRP reinforcement may be in the form of evenly spaced strips or it may be a continuous jacket. The use
of strips may be effective in optimizing the amount of material used. Furthermore, if the entire length of the beam is to be wrapped, the use of strips may allow for better moisture migration through the concrete.
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