PSI - Issue 64

Abbas S.A. Al-Hedad et al. / Procedia Structural Integrity 64 (2024) 1386–1393 Abbas S. A. Al-Hedad and Muhammad N. S. Hadi / Structural Integrity Procedia 00 (2019) 000 – 000

1390

5

at the tip of the notch of the specimens using the above expression was correct because the location of LVDTH was horizontal and firmly fixed during the cyclic loading tests. The static and cyclic loads of the specimens of Groups ST and CY were carried out using the Instron testing machine, having a capacity of 500 kN, Model 8033 (Instron Pty Ltd 2017). The static and cyclic loads with the width of crack of the specimens of Groups ST and CY were simultaneously recorded during the progress of the testing using a computer connected to the Instron testing machine. The test results of the third unreinforced concrete beam specimen of Group CY were discarded. As this specimen accidentally failed during stopping the Instron testing machine.

Aluminium plate

Steel holder

Notched concrete beam specimens

LVDTH

(a) (b) Fig. 3. (a) Test set up of the specimens of Groups ST and CY for static and cyclic loading tests, (b) Measuring the width of crack at the tip of notch of the specimens of Groups ST and CY ( D LVDTH = 20 mm for Group ST specimens and 36 mm for Group CY specimens).

3. Experimental Results 3.1. Properties of Geogrid

The properties of geogrid used in this study represent the average of test results of five triaxial geogrid samples (Table 1). The average tensile strength per unit width of the geogrid samples was 18.5 kN/m. The average tensile strain at the tensile strength per unit width of the geogrid samples was 12.1%. At 5% strain, the average secant modulus of the geogrid samples was 2.4 kN/m/strain%. 3.2. Behavior of the specimens of Group ST under Static Loading The failure mode of the specimens of Group ST is shown in Fig. 4(a). The width of crack at the tip of notch at the failure of Specimens US, GS and 2GS tested under static loads is shown in Fig. 5(a). Specimens GS and 2GS failed at the width of crack at the tip higher than the width of the crack at the tip of Specimens US. The flexural failure of Specimens GS and 2GS at the higher crack width illustrates that the geogrid reinforcement resisted the tensile stresses in spite of cracking of concrete. As a result, the flexural behavior of the specimens reinforced with the geogrid was generally improved.

(a) (b) Fig. 4. Failure of the specimens of (a) Group ST and (b) Group CY.

In terms of the width of crack at the failure of Specimens 2GS (Fig. 5(a)), the flexural behavior of Specimens 2GS was improved in comparison with the flexural behavior of Specimens US up to failure. This means that an