PSI - Issue 62

Andrea Maffei et al. / Procedia Structural Integrity 62 (2024) 1006–1013 Andrea Maffei et al. Structural Integrity Procedia 00 (2019) 000 – 000

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The verifications required by EN 1992-4 for post-installed fasteners are the following: • Verifications required for tension load: - Steel Failure of Fastener; - Concrete Cone Failure (not required with supplementary reinforcement); - Failure of Supplementary Reinforcement (steel and anchorage failure); - Combined Pull-out and Concrete Failure. • Verifications required for shear load: - Steel Failure of Fastener; - Concrete Pry-out Failure; - Concrete Edge Failure; - Failure of Supplementary Reinforcement (steel and anchorage failure); • Combined tension and shear loads: - Steel Failure of Fasteners; - Failure Modes other than Steel failure.

In order to carry out these verifications, steel yield strength is replaced with characteristic GFRP ultimate tensile strength and characteristic bond strength of steel bars is replaced with the characteristic bond strength of GFRP bars. To take into account the stirrups damage occurring during fasteners installation, the calculations are carried out by neglecting some stirrup arms considering the worst case scenario. The results of the verifications required by EN 1992-4 are shown in Table 4.

Table 4. Safety factors.

Concrete reinforcement

Description

Steel bars

GFRP bars

Tension Load

1.70 1.60 1.28 1.10 3.41 3.78 4.95 5.44 4.92 2.31 1.02

1.70 1.36 2.17 1.10 3.41 3.78 4.95 4.59 8.29 2.31 1.02

Steel Failure of Reinforcement

Tension Load

Anchorage Failure of Reinforcement Combined Pull-out and Concrete Failure

Shear Load

Concrete Pry-out Failure Concrete Edge Failure

Shear Load

Steel Failure of Reinforcement

Anchorage Failure of Reinforcement

Combined Tension and Shear - Steel failure of fasteners

Combined Tension and Shear - Failure Modes other than Steel failure

4. Cost Analysis As previously mentioned, GFRP bars are more expensive than steel bars. The average cost per kilo of GFRP bars is about three/four times that of steel bars. Considering the low specific weight of glass fiber, a straight bar has pretty much the same cost of steel while a GFRP shaped bar costs 20% more than a steel one. Table 5 shows the average cost of GFRP and steel bars in the Italian market.