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About the performance of FRP Rebar
2013-06-21 18:28:43

    Glass reinforced the basic physical and mechanical properties
    
Different glass and steel and steel, are anisotropic materials, the spindle axis, between the different components of the physical properties of FRP bars are different, because the fibers and the type and content of the resin, fiber orientation, size effect, the production process quality control and production methods on the performance of products plays an important role. In addition, the structure of the material and its application FRP bars is also affected by the mechanical properties of loading, duration, and temperature and other factors related to now briefly introduce some of the basic physical and mechanical properties of tendons.
    
A relative density
    
The relative density of FRP rebars is generally between 1.25-2.10. 4-5 times lighter than steel, (as shown in Table 1-13). Making its transport costs. Processing at the job site to reduce installation time, construction is convenient.
    
Table 1-13 Relative density fiber reinforced plastic ribs


    
(2) Tensile strength and tensile modulus of elasticity
    
FRP bars and reinforced FRP rebars is different when it reaches the ultimate tensile strength without any substantial yield deformation. The stress-strain relationship has a special function. FRP reinforcement bars and performance comparison as shown in Table 1-14, while FRP bars with size effect, that since the shear lag reasons, FRP bars close to the fiber cross-section is not subject to stress FRP reinforcement fibers along the outer surface of the stress, this phenomenon causes the strength of large diameter FRP tendons and benefits decreased tensile strength of different diameters are shown in Table 1-15.



    
At normal temperature, FRP tendons little change in the tensile strength, the lower the temperature, the higher the strength; higher the temperature, the lower the strength, more than 140 ℃ after stable. Therefore, the temperature used below, its strength without any problems.
    
FRP bars reinforced elastic modulus of about 25%, and thus enhance the flexural member FRP bars transform the moment of inertia is smaller. As a result, if the reinforcement without tension prestressed or post-processing, the design of flexural members must consider the possible deflection. Deflection of certain structural design criteria may be the limiting factor, the use of the design should take it seriously.
    
3. Compressive strength and compressive modulus of elasticity
The compressive strength of FRP bars as tensile strength, however, for most purposes, FRP tendons are not the primary factor in the compressive strength, tensile strength, compressive strength of tendons in the 550-900MPa, GFRP tendons compressive strength between the 320-420MPa. Compressive strength and tensile strength is not only relevant, but also on the surface of FRP bars are smooth or ribbed.
    
Compressive elastic modulus and tensile elastic modulus different, FRP reinforcement compressive modulus size, type, manufacturing quality control, and the sample length to diameter ratio varies less tensile elastic modulus, the same general Product tensile elastic modulus of about 77%.
    
4 shear strength
    
In general, the shear strength of the composite material is very low. Because shear strength depends mainly on the resin properties. The shear strength of GFRP bars as ultimate tensile strength of about 26%, the use of ordinary saw in the direction perpendicular to the longitudinal axis of the saw very easy. FRP bars can be adjusted in the direction so that the use of axial tension to resist shear loads, shear strength can overcome low defect.


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