*4.2. Comparative Analysis of Overall Displacement Response*

The overall transverse displacement responses of all the models are shown in Table 7. The maximum overall displacement in all the models occurred on the main beam at the corresponding position of the vault. Compared with the original model, the overall displacement envelope of Model 1 changed little. Compared with the original model, the overall displacement envelope of Model 2 changed greatly, with the maximum displacement decreasing by 28.6% and the minimum displacement decreasing by 36.2%. The SBCs greatly reduced the seismic-displacement response of the arch-bridge structure; this was largely related to the increase in the transverse stiffness of the arch bridge structure by the SBCs. Compared with the original model, the overall displacement envelope in Model 3 changed greatly, with the maximum displacement decreasing by 30.3% and the minimum displacement decreasing by 40.2%. Model 3 had the highest rate of reduction in overall displacement response of all the models.


**Table 7.** Comparison of overall displacement responses of Models.

#### *4.3. Seismic-Performance Check of Bearings*

The safety-factor CDR was obtained by using the CDR method to evaluate the safety status of the bearings under the E2 earthquake excitation of transverse bridge direction. The CDRs of the bearings were calculated by using Formula (1) and Formula (2). The safety factor needed be greater than 1 to pass the design check. The CDRs of the bearings at the top of each column are listed in Table 8.

**Table 8.** CDRs of bearings of all models.


As shown in Table 8, after replacing the spherical steel bearings at column 1# with the FPBs in Model 1, the CDR of the adjacent spherical steel bearings (corresponding to the position of column 2#) decrease. The same rule can be observed at the vault. However, since the shear resistance of the spherical steel bearings at columns 2 # and 5# in the

original model has a certain margin, the CDR value is still greater than 1 after it decreases. Similarly, the bearings of columns 3 #–9 # passed the design check. Table 8 demonstrates that after replacing columns 1 # and 10 # with the FPBs in Model 1, the displacement demand of the FPBs under E2 earthquake excitation is less than the design displacement of the FPBs (300 mm), and the CDR value is greater than 1. Therefore, FPBs passed the seismic-calculation check.

As shown in Table 8, the shear CDR of the spherical steel bearings of the arch crown increased from 0.99 to 1.2 when using the SBC in Model 2. That is, after the seismic response of the arch crown in Model 2 reduced, the shear demand of the spherical steel bearing in the arch crown also reduced. However, the shear CDRs of the spherical steel bearings at the corresponding positions of columns 1 # and 10 # remained below 1. The shear-check calculations for the spherical steel bearings at the corresponding positions of columns 1 # and 10 # still failed, and transverse-vibration-reduction measures should be taken.

As shown in Table 8, the CDR of all the bearings in Model 3 is greater than 1. Therefore, it can be concluded that all the bearings in the combination scheme passed the seismicdesign checks.

## *4.4. Comparative Analysis of Stress Response of the Transverse Connection System of the Main Arch*

Through analysis, it was found that the transverse connection system of the main arch with the highest stress of all the models was that of the horizontal diagonal bracings, and the stress-response-envelope values of the horizontal diagonal bracings are shown in Table 9.


**Table 9.** The stress response envelope values of the horizontal diagonal bracings.

Compared with the original model, the maximum tensile stress of the horizontal diagonal bracings in Model 1 decreased by 16%, and the maximum compressive stress of the horizontal diagonal bracings in Model 1 reduced by 10%. However, the horizontal diagonal bracings in Model 1 still bear a stress that is greater than the allowable compressive stress, which may lead to buckling instability.

Compared with the original model, the maximum tensile stress on the horizontal diagonal bracings in Model 2 decreased by 25%, and the maximum compressive stress reduced by 17%. The maximum tensile stress and maximum compressive stress of the horizontal diagonal bracings in Model 2 do not exceed the allowable stress, and the check was thus passed. Therefore, the application of SBCs to the CFST arch bridge can reduce the stress response of the transverse connection system of the main arch.

Compared with the original model, the maximum tensile stress on the horizontal diagonal bracings in Model 3 decreased by 38%, and the maximum compressive stress on the horizontal diagonal bracings in Model 3 reduced by 26%. The maximum tensile stress and maximum compressive stress on the horizontal diagonal bracings in Model 3 do not exceed the allowable stress, and the check on the transverse connection system of the main arch was passed. Compared with the other schemes, the combination scheme had the highest seismic-reduction rate and the best seismic-performance-improvement effect.
