**Author details**

Selcuk Bas

back-stay cables, the axial force of the tower directly increased as 56% and 60% according to the U-sup and JBSI retrofit project, respectively. Although the shear force of the main cable at the tower top-saddle decreases, the shear force of the tower at the base considerably increases since the deck forces the tower at the level of the expansion joints (tower-deck connections) leading to high additional shear force. Therefore, the bending moment of the tower at the base increases highly as similar percentage increase to that of the shear force as

In this study, St-Id concept is identified with implementation of the real suspension bridge, the Bosphorus Bridge. Each step of the concept from visualization to utilization is aimed to carry out for the bridge considering the strong wind event SHM data. The FEM calibration of the bridge is also made according to the outcomes from the experimental data analysis. Reliably established and calibrated FEM of the bridge is then adopted for the last step of St-Id approach, utilization/interpretation/decision-making. For this purpose, the multi-point earthquake analysis (Mp-sup) of the bridge is conducted. Based on the consequences of the study,

• Under the extreme wind loading, the first modal frequency (lateral symmetric) of the bridge decreased in the range of 12%. The change was only obtained in the deck modes of the bridge. The tower modes are not affected from the strong wind. This is pertinent to high

• After the extreme wind excitation, the natural frequencies of the bridge are also obtained, meaning that no damage is estimated under the strong wind. High modal periods during

• The comparison between FEM and experimental results proved that the developed model could be reliably adopted for advanced structural analysis and performance prediction of

• Under multi-point seismic excitation, the most critical components are determined as the main deck and tower base-section. The high increase in sectional force of the main and

• In spite of no movement in the lateral direction at the expansion joints according to project specifications of the bridge, lateral movement is obtained from the Mp-sup analysis at these points. Hence, shear key elements are proposed to be considered to provide the

Based on the consequences obtained from this study, St-Id approach is shown to be a robust technique for overall assessment of long-span bridges. Apart from the implementation of the all steps of St-Id, each step also gives important results, which means that the concept can be divided into certain groups according to the aim of the study. Therefore, St-Id approach is recommended to be considered for performance prediction and structural condition evalua-

side-span cables is identified to be pertinent to the response of the main deck.

shown in **Figure 13**.

58 Bridge Engineering

**6. Conclusion**

the bridge.

the following important points are concluded;

rigidity of tower box-section in transverse direction.

restricted lateral movement at the expansion joints.

tion of long-span cable-supported bridges.

the wind indicated that damping of the bridge increased.

Address all correspondence to: selcukbas@itu.edu.tr

Department of Civil Engineering, Faculty of Engineering, Bartin University, Central Bartin, Turkey
