# Structural Health Monitoring for Prefabricated Building Envelope under Stress Tests
## 2 Materials and Methods
### Method
#### 2.1.3 Testing Activities and Outcomes Analysis  
The laboratory tests for structural health monitoring sensing technologies were analyzed based on multiple testing conditions to obtain a complete comprehension of their behavior under weather conditions. The FBG/FOS and conventional sensors were analyzed to wrap up potentialities and limitations within real environment applications.  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Label** & **Description** & **Range** & **Selected Sensor** \\ \hline \multirow{6}{*}{SHM—thermal shock—temperature} & \multicolumn{1}{p{113.8 pt}}{Glazed facade needs to be designed to prevent episodes of thermal shock in vision and} & \multicolumn{1}{p{113.8 pt}}{Temperature of service with a} & \multirow{6}{*}{FBG} \\  & \multicolumn{1}{p{113.8 pt}}{spandler parts linked to the thermal variation} & & \\  & due to solar radiation and light conversion into} & & & and 120 \\  & \multicolumn{1}{p{113.8 pt}}{IR on glass and other facade components. The installation of a temperature sensor allows for collecting a set of data to support further thermal shock design.} & & & \\ \hline SHM—mechanical stress—Strain and vibration due to accidental impacts & \multicolumn{1}{p{113.8 pt}}{Facade could be stressed by extraordinary events as accidental and not possible to foreseen impacts, which could compromise the structural facade’s behavior.} & \multicolumn{1}{p{113.8 pt}}{Accidental impact—range between 6 J (1.224 mm height)} & \multicolumn{1}{p{113.8 pt}}{FBG Accelerometer} \\  & \multicolumn{1}{p{113.8 pt}}{Force washers} \\ \hline SHM—mechanical stress—Strain and vibration due to dynamic pressure & \multicolumn{1}{p{113.8 pt}}{Facade is stressed by ordinary (wind load) and extraordinary (seismic load) loads and its mechanical behavior needs to be monitored to guarantee the structural integrity} & \multicolumn{1}{p{113.8 pt}}{Pressure ranges from \(-\)3000 Pa} & \multicolumn{1}{p{113.8 pt}}{FBG Accelerometer} \\  & \multicolumn{1}{p{113.8 pt}}{Facade hangs on a brackets system fixed to the load-bearing structure through the utilization of screws specifically torqued to guarantee the right placement and performance of the facade.} & \multicolumn{1}{p{113.8 pt}}{Force washers} \\ \hline SHM—mechanical stress—torque screw & \multicolumn{1}{p{113.8 pt}}{Facade hangs on a brackets system fixed to the load-bearing structure through the utilization of screws specifically torqued to guarantee the right placement and performance of the facade.} & \multicolumn{1}{p{113.8 pt}}{} & \multicolumn{1}{p{113.8 pt}}{} \\  & \multicolumn{1}{p{113.8 pt}}{This torque needs to be preserved during} & & & \\ SHM—mechanical stress—torque screw & \multicolumn{1}{p{113.8 pt}}{building service to avoid a loss of facade performance and safety issues. The monitoring of torque (e.g., brackets on steelwork) can directly intervene to preserve the facade serviceability and detect defects as distance} & \multicolumn{1}{p{113.8 pt}}{60–120 N} & \multicolumn{1}{p{113.8 pt}}{Force washers} \\  & \multicolumn{1}{p{113.8 pt}}{Joint distance (\(\pm\)5 mm).} & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: List of defined most relevant parameters to be monitored in terms of safety.