PSI - Issue 64

Haider Mraih et al. / Procedia Structural Integrity 64 (2024) 1402–1410 Haider Maih/ Structural Integrity Procedia 00 (2019) 000–000

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2. Evaluation of Strengthening materials against Impact load Fiber-reinforced polymer (FRP) materials are widely used in the construction industry due to their high-strength to-weight ratio, availability, durability, high corrosion resistance, and relatively low cost (Teng et al., 2002). The optimal composite type for impact resistance remains uncertain. Carbon fiber-reinforced polymer (CFRP), aramid fiber-reinforced polymer (AFRP), and glass fiber-reinforced polymer (GFRP) are the most commonly used composite materials in civil structures (Shinozaki et al., 2008). Other composites like Dyneema ® (DFRP) and Basalt (BFRP) have been studied to a lesser extent. Research has primarily focused on investigating the impact behavior of strengthened structural members with CFRP, with conflicting opinions on its performance compared to other composites. For instance, Djerrad et al. (2019) confirmed that AFRP offers a superior strength-to-weight ratio and anti-impact properties compared to GFRP and CFRP. Further, Suter and Chang (2001) stated that a comparative study was conducted on 100 reinforced concrete columns with circular and square cross-sections, finding that AFRP showed better impact kinetic energy absorption than CFRP and GFRP fibers. Tang and Saadatmanesh (2005) also confirmed that AFRP has the highest strength among fibers and excellent ductility, toughness, and impact resistance. However, some studies have found no significant difference between CFRP and AFRP under impact loading (Kishi et al., 2020). AFRP is also noted for its ease of application on various shapes and sizes of structural members compared to other composites (Sinh et al., 2022). The mechanical properties of these materials play an essential role in the performance of the composite materials under various load conditions, including impact. A stress-strain curve comparison between these composite materials is presented in Figure 2 below.

Figure 2. Stress-strain curve of different composite materials (Al-Oqla and Sapuan, 2017)

In Figure 2, carbon is shown to have the highest modulus of elasticity and tensile strength, mainly when using high strength carbon (HS carbon). However, materials with lower stiffness and high strength, such as aramid and Dyneema ® , are preferred for dissipating the impact loads. These materials exhibit higher strain at failure compared to carbon. Table 1 includes the mechanical properties of CFRP, AFRP, and GFRP according to AS5100.8 (2017), and for DFRP, the data was taken from Van Dingenen (1989) research.

Table 1. Mechanical properties of different composite materials Material Tensile strength Tensile Modulus Elongation at break

Fiber aerial weight

Fiber density g/cm 3

MPa

GPa

%

g/m 2

Carbon Aramid

2600-4300

215-600

0.6-1.8

150-200

1.6 1.3 2.2

2800 2800

100

2 4

250 300 120

Glass

60

Dyneema ®

2400-3300

65-100

3-4

0.97-0.98