# Experimental Study of Steel Reinforced Concrete (SRC) Joints
## 3 Experimental Program  
### General Behavior  
The designed T-shaped specimens were tested in a Servosis test frame (model ME-406/30, Servosis, Madrid, Spain), which can apply a maximum force of 300 kN. The load can be applied as force/time or displacement/time. The vertical load was applied to each structural specimen. The design of specimens followed the guidelines of code ACI 318-05 [21] and Eurocode 4 [22]. The purpose of this task was to understand the strength behavior of each solution in the joints with different reinforcements. (Figure 7). Specimen concrete tests were conducted to know the compression strength of the concrete. The aim was to manufacture a structural concrete in the laboratory that is similar to that supplied in construction work. The objective of the tests was for the equipment to cause the specimens to break. For this purpose, gray cement type CEM-42,5 was selected, in which the dose is similar to the mixture of the aggregate used in building concrete plants. Each specimen has a volume of about 360 dm\({}^{3}\) which, along with the six cylindrical test pieces needed to check concrete strength, was estimated to be about 400 dm\({}^{3}\) of concrete. The concrete was manufactured with four mixes of 100 dm\({}^{3}\) in a concrete mixer at the same dose. The characteristics of the materials used and the results of the tests can see in Table 1.  
Eight specimens were simulated (Figure 8). Specimens P01 and P02 served to confirm the feasibility of the research line and to adjust specimens P03 and P04 with smaller cross-sections (Figures 8 and 9) in order to ensure that they are better adapted to the maximum load of the test frame. Specim P03 \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Name** & **Elastic Limit** & **Limit of Break Tested** \\ \hline Concrete & HA-25/F/20/I & Fck = 25 N/mm\({}^{2}\) & Fc = 3200 N/mm\({}^{2}\) \\ Reinforcing bars & B-500-SD & Fsk = 500 N/mm\({}^{2}\) & Fse = 619 N/mm\({}^{2}\) \\ Steel section & HEB-100-S275 & Fsk = 275 N/mm\({}^{2}\) & Fae = 335 N/mm\({}^{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Properties of the materials used in the specimens. Figure 7: Framework of the tests run in the Department of Civil Engineering laboratory. was a beam with a section of \(30\times 25\) cm and four reinforcing bars of a diameter of 12 mm. The distance between supports was 3.3 m.  
The reaction force R at the beam ends is calculated using Equation (2) and the beam bending moment at the column surface Mb can be obtained with Equation (3), according to equilibrium conditions, where P is the applied load and Lb is the length, as indicated in Figure 9.  
\[\text{R}=0.5\;\text{P} \tag{2}\]  
\[\text{Mb}=\text{R}\times\text{Lp} \tag{3}\]  
The specimen P04 had a steel section HEB 100 completely embedded, with the same reinforcing bars of P03. A steel section embedded in a T-shape, of two meters, in the longitudinal part of the beam and half a meter in the column, was introduced as reinforcement in the joint. The metallic profile was an HEB 100. P05 had with no steel section, but had P04's strength and large deflections. The specimen  
Figure 8: Cross-sections of specimens. Figure 9: Elevation view of specimens P03 and P04. P06, with a steel section HEB 100 IPN 140, was designed to support the bending stress more efficiently than the HEB if it is oriented according to its greater inertia. * P07a had a square hollow profile of 140 mm and 5 mm of thickness. This specimen cracked in the transition between the hollow profile and the reinforced concrete section. First the hollow profile was filled with concrete and after hardening, the rest of specimen was executed. * P07b. This specimen was made by testing the previous one and checking that the plastic hinge appears in the transition between the hollow profile and the reinforced concrete section. This transition zone was reinforced with two 20 mm diameter bars on both sides to ensure the crack near to the joint.