# Assessment of a Substandard Reinforced Concrete Frame's Beam-Column Joint Using Shake Table Testing
## 3 Experimental Study
### Material Properties  
The experiments undertaken aimed to establish a low uniaxial compressive strength in concrete. The RC frame was constructed at the Allianz Technical Laboratory. The compressive strength of the concrete used for constructing the scaled test specimen was determined according to the procedures outlined in the Turkish Standard TS EN 12390 [38]. This standard explicitly defines specimen dimensions, casting procedures, curing conditions, testing apparatus, and loading protocols. Concrete cube samples (150 mm \(\times\) 150 mm \(\times\) 150 mm) were cast, cured, and tested under standardized laboratory conditions, ensuring the consistency, reproducibility, and accuracy of the test results. Utilizing this standardized method provides reliable and comparable compressive strength data, essential for accurately characterizing the mechanical properties and ensuring the structural similitude between the scaled experimental model and the full-scale prototype. A series of cubic specimens were gathered and subsequently tested to verify their compressive strength. At the 28-day mark, the compressive strength of these frames, as determined through cylinder testing, was recorded at 9 MPa. The concrete mixture utilized in the scaled test specimen was specifically formulated to replicate the characteristics of substandard, low-strength concrete frequently found in older RC structures in Turkish. Concrete mixture calculations were prepared in accordance with standard TS 802 [39]. The mixture comprised crushed limestone aggregate and CEM 1 42.5R Portland cement. This concrete mixture was classified explicitly as strength class C8/10 according to the Turkish Standard. Clearly specifying these concrete constituents, strength classification, and compliance with standardized testing protocols ensures the reliability, reproducibility, and contextual relevance of the experimental results obtained from the shake table tests. Table 4 illustrates the mixed proportions of concrete, detailing the specific materials employed in the composition expressed in terms of weight relative to a single cubic meter of concrete. The choice of a concrete compressive strength of 9 MPa was deliberate, aimed explicitly at representing typical low-strength concrete extensively utilized in Turkiye during the 1980s. This period predates modern seismic-resistant construction regulations, resulting in numerous structures exhibiting pronounced seismic vulnerabilities. By selecting this strength criterion, the experimental model authentically mirrors structural deficiencies  
Figure 6: Specim on the shake table. characteristic of older RC buildings in seismic-prone regions, thereby ensuring the practical relevance and applicability of the experimental outcomes. In the construction of the structural elements, specifically the columns and beams, a total of four longitudinal deformed steel bars, each measuring 8 mm in diameter, were utilized. Both longitudinal and transverse reinforcement utilized within the scaled experimental specimen consisted of ribbed steel reinforcing bars conforming to Turkish Standard TS 708 [40], \"Steel for the reinforcement of concrete--Reinforcing steel', classified as S420 grade. The ribbed surface profile of these reinforcement bars ensures optimal mechanical interlock and improved bond performance with the surrounding concrete matrix, which is critical for accurately replicating realistic structural behavior under seismic loading conditions. The clear specifications of the reinforcement type enhance the fidelity of the scaled model, facilitating the reliable extrapolation of experimental results to prototype structural behaviors. To assess the mechanics of the stress-strain behavior of the steel used in the project, three specimens were subjected to rigorous testing. Additionally, the transverse reinforcement was also composed of bars with an 8 mm diameter.