# Development of a System for Cyclic Shear Tests on Full-Scale Walls
## 3 Test Setup Description
### Instrumentation Subsystem  
This subsystem comprises the instrumentation used in the wall specimens (Figure 19), footings and main beam, the load cell at the top of the wall level, and the data acquisition system. The servo-actuator (only one is necessary for the proposed setup configuration) provides measures of displacements and forces. In each situation, this subsystem must assume a very peculiar configuration depending on the specimen to be tested, the type of test, the key variables to be known and analyzed (forces and displacements at interest points, mainly), the surroundings of the wall to be tested, the variables necessary to be monitored for safety reasons, the reduction in noise  
Figure 18: Details of the safety devices on the actuator (**a**) on the main beam (**b**) and on the specimen (**c**,**d**). and uncertainties, among others, so the information presented below is merely illustrative of the case under study. In the present experiment, instrumentation with external displacement transducers fixed to an independent rigid aluminum support structure was performed to capture both in-plane and out-of-plane displacements of the walls, including torsional rotations. External  
Figure 19: Instrumentation of the specimens in in-plane (**a**,**b**) and out-of-plane (**c**,**d**) configurations. sensors were also installed near the base of the specimen (to capture base displacements in the direction of the main test axis) and at three points of the base footings, seeking to capture unforeseen displacements. In addition, sensors fixed to the panels were installed in four parts along the height, aiming to find the deformations at the walls' reinforcements. Sensors were also installed to capture horizontal displacements and rotations of the footing and to capture vertical displacements of the main test beam. Five types of sensors were used: (i) LVDT's (Linear Variable Displacement Transducer) with ranges of 10, 25, 100, and 250 mm, with sensitivity of \(1\times 10^{-3}\) mm; (ii) Rectilinear Displacement Transducer (Gefran) with ranges of 25, 50, and 100 mm, with sensitivity of \(1\times 10^{-4}\) mm; (iii) Inductive Linear Position sensors with a range of 400 mm and sensitivity of \(1\times 10^{-3}\) mm; (iv) Draw Wire Position sensors with ranges of 500 and 750 mm with sensitivity of \(1\times 10^{-6}\) mm; and (v) a DSCC pancake load cell/low profile force sensor with both a tension and compression capacity of 100 kN. It is important to highlight that for the principal test output analysis (performed in Section 5), only data from the load cells and the displacements at the servo-actuator and the top of the wall are necessary. However, sensors at the top and transversal to the wall help capture torsion rotations. These measures may be required (especially when the cross-section is asymmetric to the test axis) for obtaining the force component at the load cell and the component of the displacements parallel to the test axis. However, in cases where torsional behavior only significantly manifests for high displacements, this correction may be negligible. The sensor positioning is very particular for each wall design and for points of interest that one wants to investigate. Although this paper does not aim to address the whole sensor positioning at the specimen, it is recommended that one considers some recent advances in sensor placement (i.e., sub-clustering strategy and considering multi-source uncertainties), mainly when the number of sensors is restricted [34; 35]. Recent progress in the uncertainty theory and optimal control methods can be found in [36; 37]. In the present study, two sensors were positioned to register the displacements at the top of the wall, which is considered a key variable, to provide redundancy. This measure was necessary to reduce the uncertainties as the data from two sensors could be compared and validated.