## 6 Conclusions  
The objective of this research was to investigate the behavior of rebar cages reinforced with U-bolt connectors under site handling conditions through experimental and numerical investigations. To achieve this goal, 26 full-scale experimental tests were conducted on five different rebar cages, and the results were used to develop and calibrate a finite-element model of rebar cages. The key finding of this study was that the presence of U-bolt connectors allows for the elimination of internal stiffening elements. Tie-wired rebar cages (without internal stiffening elements) are prone to failure under gravity loads, while those reinforced with U-bolt connectors remain intact and undamag  
Figure 19: (**a**) Comparison of the string pot measurements with FE model predictions for one of the instrumented regions of C3-S3 (model predictions are reported in parentheses). (**b**) Law of cosines in a triangle used to calculate the shear deformation angle.  
Figure 20: Force–displacement response of Cage #3 model without U-bolt connectors under test scenario #3.  
effectiveness of U-bolt connectors in reinforcing rebar cages and preventing failure under site handling loads.  
The numerical models were developed and calibrated with the results of three tests and cross-validated with the other tests to ensure their accuracy and reliability. In addition, the models were validated on both the structural and local scales, demonstrating their ability to capture the complex behavior of rebar cages that use both U-bolt connectors and tie-wires. As a result, the numerical model can be used for future parametric studies to develop design and detailing guidelines.  
The results of this experimental and numerical study have important implications for the design and construction of rebar cages, as the application of U-bolt connectors may simplify the design process by eliminating the need for internal stiffening elements. Further investigations are currently underway to develop practical analysis, design, fabrication, and handling guidelines for rebar cages with U-bolt connectors.  
Conceptualization, M.V., H.E. and A.M.I.; methodology, M.V. and H.E.; software, M.V. and H.E.; validation, M.V. and H.E.; formal analysis, M.V. and H.E.; investigation, M.V. and H.E.; resources, H.E. and A.M.I.; data curation, M.V. and H.E.; writing--original draft preparation, M.V.; writing--review and editing, H.E.; visualization, M.V.; supervision, H.E. and A.M.I.; project administration, H.E. and A.M.I; funding acquisition, H.E. and A.M.I. All authors have read and agreed to the published version of the manuscript.  
This study is the result of a research project funded by the ASCE Construction Institute (Agreement# SP-2000500) with contributions from the Charles Pankow Foundation and several industry partners, listed in alphabetic order as follows: the Association of Drilled Shaft Contractors, the Association of Foundation Drilling, the Concrete Reinforcing Steel Institute, Harris Rebar/Nucor, the Keller Companies, the Kiewit Corporation, the Parsons Corporation, P.J.'s Rebar, Siefert Associates LLC, and Williams Form Engineering. The provided financial support is gratefully acknowledged.  
The data presented in this study are available upon reasonable request from the corresponding author.  
The authors are thankful to the Earthquake Engineering Lab staff at the University of Nevada, Reno, [PERSON], [PERSON], and [PERSON] for their dedicated assistance in the course of experimental testing. The authors express gratitude to [PERSON] from Trillion/GOM for providing the necessary software and on-site training for DIC measurement. The authors would also especially like to acknowledge [PERSON], of the project's steering committee, for his unwavering support and contribution to this research project.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analysis, or interpretation of the data; in the writing of the manuscript; or in the decision to publish the results.