*2.3. Stress-Seismic-Response Analysis of the Transverse Connection System of the Main Arch in the Original Model*

Due to the high level of rigidity of the transverse connection system of the main arch, stability is easily lost due to the large internal forces imposed during an earthquake. Therefore, the stress seismic response of the transverse connection system of the main arch was assessed.

Through this analysis, it was found that the transverse connection system of the main arch with the highest stress in the original model took the form of horizontal diagonal bracing. As shown in Figure 5, the maximum combined tensile stress on the horizontal diagonal braces was 225 MPa, and the maximum combined compressive stress was 350 MPa. The stress capacity of the members in the elastoplastic state under seismic action was calculated by using the basic allowable stress method and considering the improvement of various factors. According to the basic allowable stress method, the allowable tensile stress of the horizontal diagonal brace was 350 MPa, and the allowable compressive stress was 297 MPa. The compressive stress on the horizontal diagonal brace of the original model was greater than the allowable compressive stress; that is, the horizontal diagonal brace of

the main arch entered the elastic–plastic stage, in which it was likely to buckle and lose stability, and transverse-vibration-reduction measures needed to be implemented.
