## 2 Test Setup
### Static and Dynamic Test Procedure  
The beams were tested under cyclic quasi-static loading conditions with incrementally increasing midspan drift ratios applied in the vertical direction. The loading was performed using a speed-controlled electric hydraulic system, set at a loading speed of 20 kg/s. A total of 5 drift ratios, corresponding to specific damage levels, were defined: 0.00% (undamaged state), 1.00%, 1.50%, 2.00%, and 2.50%. The midspan displacements during the drift ratios were calculated by multiplying the drift ratios by the span length of the beam (i.e., 3000 mm). Accordingly, the beams experience cyclic midspan displacements in the vertical direction, ranging from 30 mm (i.e., 1.00% drift ratio) to 75 mm (i.e., 2.50% drift ratio). It should be noted that a test was terminated if failure was observed in a beam. Consequently, drift ratios exceeding 2.50% may occur. The drift ratios, corresponding midspan displacements, and damage levels are presented in Table 3.  
Figure 3: (**a**) Layout of the accelerometers, (**b**) schematic presentation of the static test system, and (**c**) general view of the test setup.  
In the undamaged state and at the end of each pre-determined damage level (i.e., D1, D2, D3, and D4), impact hammer tests were performed by hitting the beams at midspan in both the vertical and horizontal directions to excite the beams with an input of broad-band characteristics. If a test was terminated beyond the D4 damage level due to failure, no dynamic testing was conducted at the end of the test. Dynamic response data were recorded at a sampling rate of 1000 Hz. Pre-processing of the data was carried out in MATLAB [48]. Operational modal analysis (OMA) was conducted in the ARTeMIS Modal Pro [49] environment, employing a non-parametric frequency-domain method known as EFDD. The load cell was detached from the beams before the dynamic tests to prevent any restraining effects that could alter the stiffness characteristics of the beams. It should be noted that once the beams entered the severe non-linear range, they retained varying levels of residual deformations. When the load cell was detached before the dynamic tests, a certain amount of residual deformation remained on the beams. In other words, the dynamic tests were performed at zero vertical force but not at zero residual displacement. After completing the dynamic test for a specific damage level, the load cell was reattached, and the quasi-static test proceeded to the next targeted damage level. Note that for Beam_GFRP_PostStr and Beam_CFRP_PostStr only, the quasi-static test was paused after the dynamic test at the D1 damage level (i.e., corresponding to 30 mm midspan displacement). At this stage, the beam was removed from the test setup and strengthened as described in Table 1. A week later, once a sufficient bond between the beam and the strengthening material was achieved, the beam was reattached to the test setup, and the dynamic test at the D1 damage level was repeated. This was performed to investigate the effect of the strengthening process on the dynamic properties of the beam. Afterward, the quasi-static test continued from where it left off. In summary, Beam_GFRP_PreStr and Beam_CFRP_PreStr were strengthened in the undamaged state, while Beam_GFRP_PostStr and Beam_CFRP_PostStr were strengthened at the D1 damage level. Consequently, Beam_GFRP_PostStr and Beam_CFRP_PostStr can be regarded as bare beams prior to the strengthening process.