Akihiro Oikawa

Temperature Dependence of GFRP Box-Shaped Members Formed by Pull-Forming Subjected to Temperature Changes

Gen Hayashi

  FRP (Fiber Reinforced Polymer) is a composite material combining resin as the matrix and fibers as the reinforcing material. This material possesses multifunctionality, including lightweight properties and corrosion resistance, in addition to excellent mechanical properties such as specific strength and specific modulus. Among these, Glass Fiber Reinforced Polymer (GFRP), using glass fibers as reinforcement, has gained prominence as a primary structural material in recent civil engineering structures due to its excellent balance of cost performance and functionality. However, since the matrix resin constituting GFRP is a polymer material, its mechanical properties are known to exhibit significant temperature dependence. Civil engineering structures are exposed to harsh outdoor environments. Therefore, when applying GFRP components in practice, it is essential to quantitatively evaluate the impact of temperature changes on their structural performance.
 This study focuses on cover plates, a type of GFRP component actually being applied. Cover plates are extremely important components used to temporarily construct road surfaces in urban infrastructure projects such as subways and water sewer systems. Previous studies have reported instances where the surface temperature of road components under direct sunlight during summer exceeds 60℃. Such high-temperature environments raise concerns about significantly reducing the durability and load-bearing capacity of GFRP components.
 Therefore, this study targets pultruded GFRP box-shaped members, which are actually used as components of cover plates, aiming to clarify the temperature dependence of their bending characteristics. Specifically, four-point bending tests were conducted across a wide range of temperatures, from low to high, using a loading testing machine equipped with a constant-temperature chamber. This enabled the investigation of how temperature changes affect the mechanical properties of pultruded GFRP box-shaped members, such as flexural strength and deformation performance.