Seismic performance enhancement of museum structures using atrium steel suspension bridge systems

Traditional long-span steel frame structures often struggle to meet the "strong column-weak beam" seismic design principle, with failures typically occurring at column ends. To address this limitation, a novel seismic system integrating a zigzag suspension bridge into the atrium of a large museum was proposed. Three comparative models were established: Model I (standard frame), Model II (frame with suspension bridge), and Model III (frame excluding the atrium truss). Nonlinear time-history analyses were conducted in China State Construction Zhituo simulation software to evaluate roof displacement, interstory drift, base shear, and stress distribution under both frequent (service-level) and rare (safety-level) earthquakes. Under frequent earthquakes, Model II showed a 44.85% reduction in roof displacement and a 35.77% decrease in peak acceleration compared to Model I. This corresponds to a lateral stiffness enhancement factor of approximately 2.20, calculated based on the inverse ratio of peak displacements. Under rare earthquakes, interstory drift angles and base shear were reduced by 67.6% and 30.4%, respectively, further confirming the improved lateral resistance. Notably, the roof displacement was reduced by approximately 1.98 times, indicating a significant enhancement in lateral stiffness. In contrast, Model III demonstrated similar performance to Model II, indicating that the seismic improvement mainly derives from the suspension bridge system rather than the atrium truss. Stress contour analysis revealed pronounced stress concentrations at atrium-frame joints in Model I, implying increased collapse risk. Overall, the zigzag suspension bridge effectively redistributed seismic forces, suppressed structural deformation, enhanced lateral stiffness, and better fulfilled the "strong column-weak beam" design objective for complex public buildings.