The material properties of composite materials are affected by changes in temperature and moisture. This study used the glass/carbon fiber reinforced plastic hybrid composite (G/CFRPHC) laminate as the research object. The stiffness and strength of the composite lamina were expressed as a function of hydrothermal parameters. Based on classical lamination theory(CLT) and macro-mechanical analysis, using MATLAB programming, the tensile strength of G/CFRPHC laminates under a hydrothermal environment was studied. In addition, the influence of temperature, ply thickness, ply stacking sequence, and ply angle on the tensile strength of G/CFRPHC laminates under a hydrothermal environment was discussed. The results show that the tensile strength of G/CFRPHC laminates decreases with the increase of temperature and laying angle in the temperature range of 20℃~110℃ in the hydrothermal environment (moisture absorption rate C1=0.5%). Furthermore, for the G/CFRPHC laminates with laying modes of (02G/90mC)S, (04G/90mC)S, (06G/90mC)S, as m increases, their tensile strength gradually decreases. The tensile strength of G/CFRPHC laminates with the same ply angle but different ply stacking sequence is also not the same.

The work reported here shows that steel fibres can reduce the expansion caused by alkali–aggregate reaction in concrete, hereby decreasing the resulting strength loss. The addition of 1–1·5% of steel fibres by volume allowed us to increase the alkali content by about 2 kg/m3. Under such conditions, the ultrasonic pulse velocity was found to be stable, and the expansion rate low, indicating only minor effects on the strength of the concrete, even though the concrete contained reactive aggregate and a high alkali content. More specifically, the effliciency of fibres for restricting expansion is governed by the size and geometric parameters of the fibres. The expansion rate was linearly related to the so-called fibre factor or fibre index, for otherwise similar alkali–aggregate reaction conditions.