Seismic Response and Parametric Control of Curved Steel Tube Trusses Under Traveling Wave Effect

Large-span spatial structures are sensitive to spatially non-uniform seismic excitations (e. g., traveling wave effects). To deeply reveal their dynamic response mechanisms and evaluate the influence of key component parameters, this study took a curved steel tube truss project with a span of 67.5 m in Leshan City, Sichuan Province, as the research object and developed a refined finite element model validated by on-site modal testing. The mode decomposition response spectrum method (CQC method for mode combination) was used to analyze the structural response under frequent and rare earthquakes. Three load cases were studied by focusing on the effects of variations in the outer diameter and wall thickness of the bottom chord on displacement and stress. An optimization model was established with the objective of minimizing the total structural mass and constraints on deflection and stress. The time history analysis method was adopted to consider the traveling wave effect. Borrego wave, EI Alamo wave, and one artificial wave were selected to compare the peak displacements, axial forces, and shear forces at key structural locations (arch crown, tower top, tower base) under uniform excitation and traveling wave excitation. The results show that the traveling wave effect significantly alters the response distribution, aggravates the non-uniformity of displacement and internal forces, and leads to a significant increase in peak displacement and internal forces at key positions such as the arch crown, tower top, and tower base compared to those under uniform excitation. Under the traveling wave effect, the peak displacement at the tower base increases to 1.8 times, 1.5 times, and 2.6 times that under uniform excitation for the Borrego wave, EI Alamo wave, and artificial wave, respectively. The axial force at the arch crown increases by 80%, 37% and 104% under the Borrego wave, EI Alamo wave and artificial wave, respectively, accompanied by a significant time lag in the response. Compared with adjusting the wall thickness, adjusting the diameter of the lower chord members has a more significant effect on the structural deflection and stress. After optimization, the outer diameter of the lower chord is 96 mm and the inner diameter is 89 mm, resulting in a 13.06% reduction in steel consumption. The traveling wave input induces a significant time-lag and amplitude amplification effect, which becomes more prominent as the long-period component increases. This study elucidates the response characteristics and the controlling role of key components of long-span curved trusses under non-uniform excitation, providing a basis for seismic design and a strategy for parameter control in similar structures.