# Cyclic Tests and Numerical Analyses on Bolt-Connected Precast Reinforced Concrete Deep Beams
## 5 Conclusions and Discussions  
In order to understand the mechanical behavior and seismic performance of RDBs, two scaled specimens were designed and tested under cyclic loads, and the corresponding nonlinear FE models were established and verified. The conclusions are listed as follows:  
1. The first crack formed at the corner of RDB-A due to large normal stress, but the first crack of RDB-B formed at the center region due to large shear stress. Besides, the RDB-A failed with a bending-shear failure mode for both typical horizontal and diagonal cracks that developed in the RDB-A; while the RDB-B failed with a shear dominating failure mode, as only diagonal cracks were observed in RDB-B. This indicates the bending-shear dominated mechanical behavior of RDB-A and the shear dominated mechanical behavior of RDB-B;
2. By comparing the RDB with the height-to-length ratio of 2.0, the ultimate capacity, initial lateral stiffness and displacement-based ductility of the RDB with a height-to-length ratio of 0.75 increased 277%, 429% and 141%, respectively. This indicates that the height-to-length ratio is a good choice to adjust the capacity and stiffness of RDB to cater to the performance requirement of building structures;
3. According to the parametric analysis, the shear resistance, elastic lateral stiffness and displacement-based ductility are significantly enhanced when decreasing the height-to-length ratio of RDB, which is similar to the test results. The height-to-thickness  
Figure 13: Effects of parameters on seismic performance of RDBs.  
ratio shows a general influence on the seismic performance of RDBs, but the effect of concrete strength on the seismic performance of RDBs is relatively small.  
The bolt-connected RC deep beam (RDB) proposed in this paper is quite different from other types of RC shear walls. The bending-shear mechanical characteristic of RDBs is a benefit for the plastic development of RC materials. The length of RDBs could be an effective parameter to adjust the lateral stiffness and resistance of frame structures, and the RDBs could be flexibly arranged to achieve the architecture requirement. According to the failure patterns of RDB specimens, the bolt connection was effective to ensure the performance utilization of RDBs. Thus, the bolt connection could be treated as a reliable connection for RC deep beam and boundary frames. The authors have conducted experimental and numerical analyses on steel frames with steel panel walls, RC panel walls and composite steel panel walls [17; 18; 19; 20]. The aim of this paper is to investigate the seismic performance of RDBs solely and to understand the collaborative working relationship between the steel frames and RDBs. We found that the seismic performance of the steel frame with RDB specimens is better than the sum of the steel frame and the RDB based on the test results. Though the numerical model developed in this paper is simplified compared to the macroscopic model [20], the simple model proposed in this paper has relatively good accuracy in predicting the lateral resistance of RDB.  
Conceptualization, H.Z. and L.J. ([PERSON]); methodology, J.L. and H.Z.; software, J.L. and H.Z.; validation, J.L., H.Z. and L.Z.; investigation, J.L., H.Z. and L.Z.; writing--original draft preparation, J.L. and L.J. ([PERSON]); writing--review and editing, L.J. ([PERSON]) and L.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China, grant number 50678025.  
Not applicable.  
The results presented in this study are available on request from the corresponding author. The data are not publicly available due to the reason that the authors are conducting further analysis on the same structural model.  
We would like to thank the editors and reviewers for the comments on the manuscript.  
The authors declare no conflict of interest.