Performance analysis of U-shaped viscoelastic seismic brace for pipelines

The conventional seismic brace (CSB) reduces pipeline horizontal deformation under seismic loads by providing lateral stiffness. However, CSBs fail to dissipate extra seismic energy and consume energy merely through large deformation, which easily causes local buckling and brace damage, and further leads to pipeline failure. To solve this problem, this paper proposes a novel U-shaped seismic brace (NSB). With an arc sliding mechanism, NSB converts excessive horizontal displacement into curved displacement, and adopts viscoelastic materials at sliding parts for energy dissipation. Numerical models of NSB are established using experimentally calibrated viscoelastic parameters, and its seismic performance is compared with CSB. Compared with CSB, NSB reduces maximum stress by 32.36% and eliminates stress concentration. Meanwhile, its residual displacement decreases by 26.22%, and yield displacement increases by 171.17%. Featuring better seismic performance and smaller installation space, NSB provides more reliable protection for pipeline systems. Theoretical analysis proves that viscoelastic material thickness is a key influencing parameter. Parametric analysis is thereby conducted to explore its effects on NSB seismic performance. Results indicate that NSB with proper viscoelastic material thickness achieves optimal seismic performance and favorable engineering applicability. In addition, analysis was conducted on different viscoelastic materials, and the results showed that different viscoelastic materials can alter the seismic performance of NSB. Finally, an analysis was conducted on NSB at different frequencies.This study proposes a new device to improve pipeline seismic safety.