## 3 Shake Table Study
### Test Specim  
The conducted experiments employed an advanced biaxial seismic shake table, located at the Allianz Teknik Earthquake and Fire Test and Training Center in Istanbul, Turkiye, measuring 3.0 m by 3.0 m, which has a payload capacity of up to 10 tons. This sophisticated apparatus effectively replicates real seismic ground motions, functioning within a frequency spectrum of 0 to 50 Hz and achieving peak accelerations of 1 g. Moreover, the shake table is equipped with hydraulic actuators alongside sophisticated adaptive control systems that utilize differential pressure stabilization, thereby guaranteeing precise and dependable reproductions of seismic activities. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Physical Quantity** & **Artificial Mass Simulation [28]** & **Scale Factor** \\ \hline Length, \(l_{r}\) & \(l_{r}\) & 3 \\ Modulus of elasticity, \(E_{r}\) & \(E_{r}\) & 1 \\ Time, \(t_{r}\) & \((l_{r})^{1/2}\) & 1.732 \\ Gravitational acceleration, \(g_{r}\) & \(1\) & 1 \\ Strain, \(\varepsilon_{r}\) & \(1\) & 1 \\ Acceleration, \(a_{r}\) & \(1\) & 1 \\ Frequency, \(\omega_{r}\) & \((l_{r})^{-1/2}\) & 0.577 \\ Velocity, \(v_{r}\) & \((l_{r})^{1/2}\) & 1.732 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The calculated physical quantities for shaking table tests. Two 1/3-scaled RC frames, emblematic of standard Turkish RC structures from the 1980s, were constructed. These models were designed in accordance with the prevalent practices of the time, which were marked by insufficient seismic detailing. Specimen 1 functioned as the unretrofitted control specimen, whereas Specimen 2 was retrofitted with diagonal TnT bracing, a seismic enhancement option chosen for its capability to effectively channel lateral seismic forces directly into the foundation. This retrofitting method also enhances energy dissipation via axial deformation, contributing to the reduction of bending stresses experienced by the frame components. The structural simulations that were performed were characterized by the careful application of columns with a rectangular cross-section, measuring 100 mm in width and 150 mm in height, spaced intentionally at 1350 mm apart from one another. Each column incorporated four longitudinal reinforcement bars, each with a diameter of 8 mm, which represents the smallest reinforcement bar size commonly available for construction in the local area. The vertical dimension of these columns reached 950 mm, extending from the foundation base to the underside of the slab, thereby offering substantial structural support. As depicted in Figure 5, the transverse reinforcement in these columns consisted of 8 mm diameter bars spaced at 100 mm intervals, with stirrups featuring 90-degree hooks, which indicate suboptimal detailing. Additional 8 mm diameter bars were used at 100 mm intervals in the upper and lower slab sections, enhancing structural integrity and load distribution. The foundation's longitudinal reinforcement comprised robust 16 mm bars, with 10 mm stirrups spaced at 150 mm intervals to withstand various loads. The top slab measured 1450 mm in length, 450 mm in width, and had a thickness of 50 mm, contributing to its durability. A foundation beam measured 1950 mm long, 600 mm wide, and 400 mm deep, securely anchored to the shaking table with 50 mm diameter bolts for stability. Specimen 2 has been carefully constructed to serve as a precise imitation of the original specimen while integrating an enhanced TnT bracing system, as demonstrated in Figure 5, which visually depicts the structural advancements. The principal aim of the seismic retrofit was to markedly improve the strength and stiffness of the original reinforced concrete frame, thereby surpassing its initial load-bearing capacity to meet contemporary structural demands. The TnT bracing system exemplifies an advanced engineering approach with its intricate tube-in-tube configuration.