**2. Experimental Program**

In this section, the three testing sets of specimens are described, i.e., the isolated structural walls, the structural frames, and the real-scale three-storey precast concrete building, as well as the low-cost energy dissipation system and the shake table. Additionally, the testing procedure is described.

#### *2.1. Isolated Structural Wall*

As explained before, the isolated structural walls are composed of a precast structural wall and a precast footing, connected through the low-cost energy dissipation system.

The structural wall is a conventional reinforced concrete precast element 3.0 m high, 2.0 m wide, and 16 cm thick. The wall is placed on a reinforced concrete precast footing, 1.1 m wide, 2.0 m deep, and 0.6 m high. In both cases, the concrete quality is C30/37, according to Eurocode 2 [35]. The compressive strength was obtained following the method described in standard EN 12390-3 [36]. The footing includes a longitudinal pocket 36 cm wide and 36 cm high, where the structural wall is placed. Underneath the wall, a 2 cm neoprene band is placed. The structural wall is rigidly connected to the footing through the low-cost energy dissipation system, which is described later (Figure 1).

**Figure 1.** Elevation view of the isolated structural wall.

The structural wall is reinforced on both faces with steel rebars 8 mm in diameter spaced 150 mm in both longitudinal and vertical directions.

## *2.2. Structural Frame*

The structural frame is composed of two isolated structural elements, as described above, connected with a structural concrete slab. The inner distance between the walls is 3.84 m. The slab is composed of a self-supporting precast prestressed concrete slab with a thickness of 8 cm and an upper layer of 14 cm of cast in situ reinforced concrete. The total thickness of the concrete slab is 22 cm. In all cases, the concrete quality is C30/37, according to Eurocode 2 [35].

A "flexible" connection between the walls and the slab was used, which is described next. The self-supporting precast prestressed concrete slab rests on a steel corner profile anchored to the walls using a set of mechanical anchorages. Additionally, a row of conventional steel rebars sew the joint between the wall and the cast-in situ slab. The rebars are L-shaped with a length of 800 and 200 mm, respectively. The long leg of the rebar is placed horizontally inside the cast-in situ reinforced concrete slab, while the short leg is placed vertically inside the wall. The diameter of the rebars are 20 mm, with a spacing of 50 cm. From the structural point of view, this connection is very e ffective under vertical loads, such as self-weight, dead loads, and vertical live loads. Under horizontal loads, similar to the ones caused by the earthquake, this connection is able to withstand negative bending moments, but not positive bending moments, resulting in a semi-rigid joint. (Figure 2).

**Figure 2.** Elevation view of the structural frame.

#### *2.3. Real-Scale Three-Storey Precast Concrete Building*

Finally, the real-scale three-storey precast concrete building is composed of two precast concrete walls, two precast footings, two concrete slabs, and a flexible steel roof. The inner distance between the two walls is 2.25 m. In all cases, the concrete quality is C30/37, according to Eurocode 2 [35].

The structural walls are conventional reinforced concrete precast elements 5.62 m high, 2.0 m wide, and 16 cm thick. They are placed on the same reinforced concrete precast footings as described above.

Each of the two concrete slabs is composed of a self-supporting precast prestressed concrete slab with a thickness of 8 cm and an upper layer of 14 cm of cast-in situ reinforced concrete. The connection between the slab and the wall is the same as the one described in the previous subsection. The slabs are located at 2.45 m and 4.20 m high. Finally, the roof is located at the top of the walls. It is a lightweight roof formed by an aluminium sheet which is bolted to two I-beams. (Figure 3).

**Figure 3.** Elevation view of the real-scale three-storey precast concrete building, including the shake table.

#### *2.4. Low-Cost Energy Dissipation System*

The low-cost energy dissipation system is a device placed on the connection between the footing and the wall. As previously explained, the footing includes a longitudinal pocket 36 cm wide and 36 cm high, where the structural wall is placed. It consists of a set of threaded bars placed orthogonally to the wall, in such a way that they cross both the footing and the wall. In this case, the system consists of a total of 10 threaded bars, 20 mm diameter, and placed in two rows, spaced 300 mm in both longitudinal and vertical directions. The property class of the steel for the threaded bars is 3.6, according to ISO 898-1 [37].

Since the wall has a thickness of 16 cm, there are two 10 cm gaps between the wall and the footing, one at each side of the wall (Figure 4). Additionally, nuts located at both sides of the wall and the footing are required to fix the wall in its proper position.

When an earthquake occurs, it is expected that most of the energy is consumed in the plastic deformation of the bars, preventing the rest of the structure from damage. The number, position, distribution, and diameter of the bars, as well as the steel quality must be specifically designed to each particular structure, depending on the dimensions of the structure and the location of the building.

One additional advantage of this solution is that bars are easily replaceable once an earthquake has occurred.

**Figure 4.** Scheme of the low-cost energy dissipation system.
