PSI - Issue 64

Nikhil Holsamudrkar et al. / Procedia Structural Integrity 64 (2024) 815–821 Holsamudrkar Nikhil et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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Strengthening was done on the beam’s soffit using two layers of C-FRCM employing different preparation methods (S1, S2, and S3). In the case of methods S2 and S3, anchorages are installed before installing the FRCM system, with an anchor spacing of 400 mm uniformly along the beam's center. Spike anchors are used in the study as reported previously by Aljazaeri et al., 2019. This spacing was chosen to prevent slippage for two layers, as suggested in prior research (D’Ambrisi et al., 2013) . Each specimen is identified by the impregnation strategy (S1, S2, and S3) followed by NA for non-anchored or AN for anchored.

Table 1. Properties of the materials used in the study Compressive Strength (MPa)

Tensile Strength (MPa)

Elongation (%)

Concrete grade M35

33.8

4.5 * 581

-

Steel TMT rebars grade 550D FRCM fabric impregnated Pre-impregnation polymer matrix

- - -

16

1882.6

2.4 2.1

60

Cementitious matrix

68.5

5.9 *

-

* Flexural strength is reported

2.2. Test Setup and AE Test Parameters A four-point bending setup was utilized, as shown in Fig 1. A beam spreader was used with loading points spaced apart by 800 mm. Also, beams are supported at 200 mm from the edges, making a clear span of 2600 mm. All beams were subjected to quasi-static loading with a constant 1 mm/min displacement rate. The test setup is shown in Fig. 1, where two supports have a 200 kN load cell capacity, and an actuator has a capacity of 500 kN. The front face of the beam was monitored with 2D DIC, with images captured at a rate of 0.33 Hz using a single camera. The speckle pattern was created with stamping pads of size 0.26 inches. The vertical displacement is measured with linear potentiometers indicated by LP1, LP2, and LP3 in Fig 1. Three AE sensors were placed at the bottom and back face around the central third portion of the beam. Signals were pre-amplified with 40 dB. To eliminate the machine and other surrounding noise, the threshold was set at 40 dB.

Fig. 1. Test setup for AE-based health monitoring