## 2 Experimental Program
### Testing Procedure  
#### 2.6.1 Pushover Tests on Isolated Structural Walls and Structural Frames  
The pushover tests carried out on the isolated structural walls and the structural frames were developed according to the American standard ACI374.2R-13 [34]. According to this standard, four levels of structural performance under seismic events are defined, which are \"operational\", \"immediate occupancy\", \"life safety\", and \"collapse prevention\", moving from least to greatest lateral drift ratio (Figure 7). According to the goal of this research, the \"immediate occupancy\" level is considered for design purposes, which implies that the building can be used once the seismic event has passed. At this level, the stiffness requirements are high, the behavior of the structure must be within the elastic-linear range and, consequently, the seismic loads developed are important. The standard used does not consider other criteria apart from those concerning structural damage. That is the reason why non-structural issues, such as furniture overturning or partition damage, have not been considered in this research. However, it is worth noting that the \"immediate occupancy\" level implies a very low risk of life-threatening injury as a result of structural damage. The lateral drift ratio is defined as the quotient between the horizontal displacement of the structure at the loading point and the distance from this point to the centroid of the connection between the wall and the footing. In this case, the maximum allowable lateral drift ratio (see Figure 7) is 0.5%. Additionally, some other criteria must be fulfilled [34]:  
1. No plastic behavior is observed in the structure, neither concrete nor steel rebars;
2. Crack width should be below 1.6 mm;
3. No concrete crushing is observed. Regarding the testing procedure, it consisted of applying a quasi-static horizontal load near the top of the structural element (wall or frame). Displacement controlled reverse cyclic tests were performed. The number of loading cycles for each amplitude of the imposed displacement was kept at two. The value of the amplitude depends on the critical drift \(\varphi_{y}\), which is defined as the drift associated with yielding. The first couple of cycles corresponded to a drift equal to 0.5-\(\varphi_{y}\), the second couple of cycles, to a drift equal to \(\varphi_{y}\), the third one, to a drift equal to 2-\(\varphi_{y}\), and for the remaing couple of cycles the amplitude increased in 1-\(\varphi_{y}\), i.e., 3-\(\varphi_{y}\), 4-\(\varphi_{y}\), 5-\(\varphi_{y}\), and so on to the conclusion of the test. The test concluded when the maximum load of one cycle was more than 20% lower than the total maximum load of all cycles, according to ACI 374.2R-13 [34]. In the case of the tests on the isolated structural walls, the load was applied at a height of 2.5 m and the critical drift \(\varphi_{y}\) corresponded to a horizontal displacement of 10.6 mm at the load application  
Figure 7: The four levels of structural performance, according to ACI 374.2R-13 [34]. point. In the case of the tests on the structural frames, the load was applied at a height of 2.94 m and the critical drift \(\varphi_{y}\) corresponded to a horizontal displacement of 12.6 mm at the load application point. The tests on both the isolated structural walls and the structural frames were carried out using a tension-compression MTS 201.70F dynamic actuator (MTS, Eden Prairie, MN, USA), with a capacity of \(\pm\)1000 kN. The actuator had a load cell MTS 661.31F-01 (MTS, Eden Prairie, MN, USA), with a range of \(\pm\)1000 kN and an error of below 1% of the range. The tests were displacement controlled. This testing procedure provided greater safety against unexpected collapse and it better meet the requirement of the ACI 374.2R-13 [34].