Smart retrofitting of irregular steel joints in traditional Chinese buildings by viscous dampers

Ancient Chinese architecture is characterized by its unique appearance and exhibits high standards in terms of structural and artistic aspects. Most of these buildings were constructed with wood, which is expensive to maintain. Given the urgent requirement to preserve and pass on the historical architectural heritage, traditional Chinese buildings (TCBs) are being constructed using modern fabrication techniques and building materials that imitate the shape and appearance of ancient Chinese timber structures. To prevent premature failure and increase the strength of the irregular joints in TCBs, viscous dampers are attached to retrofit these irregular steel joints, instead of containing the relatively weak Dou-Gong (a unique component in TCBs). Four newly proposed 1/2.66-scale joint specimens with viscous dampers were fabricated and tested under fast dynamic periodic loads, and two other counterparts without dampers were tested for comparison. The influence of the damping coefficients of the viscous dampers on the dynamic performance of retrofitted irregular joints (including single beam-column joints and double beam-column joints) was assessed by their hysteretic behavior, strength, ductility, energy dissipation capacity, and stiffness degradation. The test results showed that the plastic hinge region moved outwards after the dampers were installed. The existence of dampers increased the strength of the irregular joints by 14.4%-41.7%. However, low ductility was exhibited by the irregular steel joints regardless of the installation of dampers, indicating that an appropriate design should be ensured for these joints to improve the damper function. A refined finite element (FE) model was developed based on the experiments, and the optimized installation configurations of dampers for irregular steel joints in TCBs, that is, the length and installation angle of dampers, were discussed. The proposed retrofitting method has been proved to be effective for reinforcing irregular steel joints in TCBs.