# Effectiveness of LRB in Curved Bridge Isolation:
## 8 Conclusions  
The efficacy of LRBs as isolation bearings for curved bridges has been examined for various ground motions. The effect of the incidence angle of the earthquake on the uni-directional and bi-directional responses of the bridge was determined. Sensitivity analyses were performed for various time periods and damping ratios of the LRBs. Bi-directional loading effects of ground motions on the response of the bridge were also investigated. The following are the important conclusions of the above study. LRBs can significantly reduce the curved bridge forces, especially the pier torsional moment, by about 94%, compared to non-isolated conditions. The maximum decrease in forces was found for the Imperial Valley and Kobe earthquakes. In the cases of Imperial Valley and Kobe ground motions, the maximum reduction of force transmitted to the pier was about 84 to 85% for uni-directional cases and 93 to 95% for bi-directional cases, while in the case of Turkey ground motion, the maximum reduction of force transmitted to the pier was about 44 to 71% for uni-directional cases and 56 to 83% for bi-directional cases. The variations of bridge response are found to be non-linear for design parameters of the LRBs, such as the natural time period and damping ratio, which are supposed to be due to the non-linear force-deformation behavior of the LRBs considered by the coupled plasticity model. The deck displacement of the LRB isolated bridge was increased, and the maximum effect was observed for Turkey ground motion, especially at higher periods. It is crucial as per the design of isolation bearings. For most of the response parameters of the bridge, the variations observed were small, except for the pier torsional moment, which was the maximum for an incidence angle of 67.5\({}^{\circ}\) to 90\({}^{\circ}\). The variation of response parameters is more sensitive with respect to the time period than the damping ratio of the bearings. For various earthquake ground motions, a large variety of bearing displacement with respect to damping ratio was observed for Turkey ground motion, especially at higher time periods, which might be due to the forward directivity effect. However, for bi-directional Turkey earthquake motion, the steepness of variation of bearing displacement has been reduced compared to the same for uni-directional motion. The pier torsional moment variations are almost insignificant for a higher range of time periods, whereas they are more sensitive at lower time period ranges. In the case of the Imperial Valley earthquake, the maximum variation of pier torsional moment was observed at lower time periods for both uni-directional and bi-directional loadings. The effect of bi-directional ground motion is found to be crucial as the same has enhanced the response of the bridge by a significant amount. The maximum effect has been found for Turkey ground motion, which has increased the deck acceleration, the force transmitted to the pier, pier torsional moment, and deck displacement by about 98%, 95%, 90%, and 102%, respectively, over the uni-directional case. The results infer the importance of the forward directivity effect in the design of the isolated curved bridge. Conceptualization, P.K.G. and G.G. Data curation, P.K.G. ; Formal analysis, P.K.G. and S.D. ; Investigation, P.P. ; Methodology, P.K.G. and V.K. ; Project administration, P.K.G. ; Supervision, V.K. ; Validation, P.P. ; Visualization, V.K. and S.D. ; Writing--original draft, P.K.G., P.P. ; Writing--review and editing, [PERSON]. All authors have read and agreed to the published version of the manuscript. The research work mentioned in this paper was financially supported by the Science and Engineering Research Board (SERB), Department of Science and Technology, New Delhi. Thanks to SERB and the University of Tromso for their support. Not applicable. The authors have no relevant financial or non-financial interest to disclose. * _[PERSON] et al.