Pultruded fiber reinforced polymeric plastic (PFRP) has many advantages such as high corrosion resistance, high specific stength/stiffness, light weight, etc. Pultrusion is a manufacturing process for producing continuous lengths of reinforced polymeric structural shapes with constant cross-section. The mechanical property of PFRP is usually regarded as an orthotropic material. The pultruded structural shapes are usually composed of thin-walled plate element. Because the composite material has relatively low elastic moduli, the design of pultruded compression members may not be governed by the material strength limit state but by the stability limit state such as the local buckling. Therefore, the stability limit state must be checked to design pultruded thin-walled compression members. In this paper, we present the analytical study results of elastic buckling strength of PFRP orthotropic plates with different fiber volume ratios. The local buckling analysis of pultruded compression members was conducted for various composite materials using the closed-form solution. From the study it was found that if E11/E22 is increased then the plate buckling coefficient, hence the plate buckling strength, is decreased.

The elastic modulus of high-strength steel fiber reinforced concrete was measured 37 GPa to 41.98 GPa. Comparing the difference value of the measured stress and the stress calculated by the regression analysis results were within ± 1 MPa. Measured data acorrding to applied LPF was more stable than unapplied LPF data. but, it was slightly different.