## 5 Conclusions  
From this study, it is understood that RCC beams undergo ductile failure with lateral displacements as the steel material has high elasticity of modulus that increases rigidity and moment of inertia so that it can withstand heavy loads and undergo larger deflections before failure. The maximum surface crack width evaluated from DIC analysis is found to be 0.147 mm for RCC beam. The load displacement curve declares that dial gauge and digital camera DIC and UAVIC investigations results are similar, with a variation of 12%. UAVIC investigation shows small spikes in the displacement recordings, it is due to magnetic sensitivity of sensors and vibrations in the UAV. While conducting the study, authors observed a small drift in the UAV due the availability of heavy machinery like Universal Testing Machine (UTM) attractions in the laboratory conditions. In field conditions, while monitoring the bridge, the wind pressure caused the drift in the drone, gimbal played a major role in locking the view of target point. The UAVIC has proved to be a preliminary assessment tool at inaccessible locations in RCC structural monitoring. Based on the deterioration studies it is understood that the crack width in the bridge exceeded the permissible limits, and it should be treated with fibers [38,39]. Usage of self-healing concrete in the wide opened cracks also prevents future deterioration [36]. In terms of concrete spalling, the severity level is categorized as 1, and near maintenance is required [40]. The investigated bridge needs immediate and periodic maintenance for enhancing the serviceability of the structure. For obtaining the better results, bridge monitoring studies can only be conducted on highly sunny days with low windy conditions in the field. Rather than a quadcopter, an octocopter would yield better results for its better stability and improved hovering time at in-situ conditions. The dust on the bridge beam acted as a speckle pattern; in exceptional condition speckles should be drawn on the beam to conduct the study. As a future scope of study, to stabilize the UAVIC images a laser referencing system by placing the lasers at four corners of the target would yield high-precision results.  
Conceptualization, K.K., S.M., V.R.K. and A.K.S.; methodology, K.K., S.M., V.R.K. and A.K.S.; validation, K.K, S.M., V.R.K. and A.K.S.; formal analysis, K.K., S.M., V.R.K. and A.K.S.; writing--original draft preparation, K.K., S.M. and V.R.K.; writing--review and editing, K.K., S.M., V.R.K., N.V.S.K.M. and B.J.; supervision, S.M., V.R.K. and A.K.S. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data that support the findings of this study are available from the corresponding author upon reasonable request.  
The authors are thankful to the Department of Civil Engineering, National Institute of Technology, Warangal, Telangana, India, for providing lab facilities and support to carry out this research work.  
This manuscript has not been published or presented elsewhere in part or entirety and is not under consideration by another journal. There are no conflicts of interest to declare.  
\begin{table}
\begin{tabular}{c c c} \hline
**Bridge Component** & **Crack Width in mm** & **Crack Length in mm** \\ \hline (A) Crack in the joint and damage of beam & 1.82 & 583 \\ (B) Crack in the deck of the bridge & 2.42 & 467 \\ (C) Damage and crack in the pier & 0.96 & 328 \\ (E) Crack in the beam and slab joint & 3.28 & 524 \\ \hline \end{tabular}
\end{table}
Table 3: UAVIC captured bridge elements crack properties.