## 2 Materials and Methods  
### Monitoring Development and Implementation  
The utilization of a combination of global and component monitoring has been well explored in other published work from our research group [9; 19; 20; 21] and will only be  
Figure 1: Research program from 2012 to today, depicting scale and ensuing investigations, including key findings such as linear vice exponential decay seen in short- and full-length specimens represented in the bottom centre graphs [9; 17; 18].  
briefly summarized herein, with additional details on changes given. Displacements and applied load are captured through a combination of Linear Variable Differential Transformers (LVDTs) and the Material Testing System's (MTS) actuator and load cell. Component monitoring was accomplished through the use of fiber optic sensors. Fiber optic sensors offer numerous benefits over the traditional strain gauges used in other research [22; 23; 24; 25]. The studies that utilize traditional strain gauges experience limitations because each individual sensor requires two wires to pass the current through [26]. This limits the number of sensors which can be used without presenting conformance issues due to the inference of all the wiring required. Fiber optics present a solution to this as they offer a spatial resolution of 0.65 mm and only require one fiber for the monitoring of the entire specimen. These sensors are made by our research group in the laboratory and installed within grooves biaxially to capture the axial response of the members. This technique leverages Rayleigh Optical Frequency Domain Reflectometry (ROFDR), in which cross-correlation from elastic scattering produced by a tunable light can produce strain results [27; 28] utilizing a Luna ODISI-B analyzer. This methodology is able to produce a 0.65 mm spatial resolution of the purely axial response of the component for which it is affixed. This research effort is novel due to a few changes being made to optimize the implementation of the fiber optic sensors. The fiber was installed along the longitudinal rib instead of the transverse ribs to prevent conformance issues as the transverse rib is key to the mechanical interlock. The fiber was also debonded along the unsupported length (the length between the loading and the embedment length) and slightly into the specimen (2.5 cm) to prevent premature failure of the sensor during yielding and conical grout failure. This was accomplished by covering the grooves with a thin layer of tape and epoxy such that the fiber could move freely. Due to this debonding, results are not present for the first 7.5 cm, to account for both the debonding in the conical grout failure potential region, and activation length of the fiber. This was confirmed as 50 mm from the conducted tensile testing and was found to be similar with other conducted research [29]. This tensile test was conducted utilizing a rebar specimen from the laboratory investigation, with 6 strain gauges paired and one length of DOS. The specimen was brought to yield and the results between the instruments were compared. This can be seen in Figure 2.  
Figure 2: Results from the tensile test for strain activation length of the fiber with comparison to strain gauges.  
Fiber was also installed on the outside of the pipe to capture the dilation behaviour of the confining medium. This was done in a similar biaxial manner but aligned perpendicularly to the longitudinal ribs of the rebar. This orientation was selected because the longitudinal rib region should have the lowest dilation as this rib does not generate outward force through mechanical interlock. The full suite of instrumentation used to monitor specimen behaviour can be seen in Figure 3. A summary of the selected instrumentations and their accuracy can be found in Table 1.