SEISMIC PERFORMANCE ANALYSIS OF COMPOSITE STRENGTHENED SQUARE TIMBER COLUMNS

In order to improve the bearing capacity and seismic performance of square timber columns and improve the seismic safety of ancient wooden structures, a composite method with near surface mounted steel bars and wrapped CFRP (Carbon Fiber Reinforced Polymer) strips is proposed to strengthen the timber columns. Low cyclic loading tests were carried out on square timber columns to study the influence of different strengthening modes, amount of steel bars and CFRP strips on the seismic performance. The finite element software OpenSees was also used, and the reliability of the finite element model was verified by comparing the analytical and experimental results. The effects of axial load, steel bar diameter and the number of CFRP layers on the hysteretic behavior, lateral bearing capacity, ductility, stiffness degradation and energy dissipation capacity of composite strengthened square timber columns were analyzed. The results show that the near-surface mounted steel bar can significantly improve the lateral bearing capacity and energy dissipation capacity of square timber columns; the external CFRP strips can limit the lateral deformation of timber and protrusion of mounted steel bars, and can improve the ductility and reduce the stiffness degradation of square timber columns; the composite strengthening method can significantly improve the lateral bearing capacity, ductility, energy dissipation capacity, as well as the stiffness and strength degradation of square timber columns. In conclusion, the effectiveness of composite strengthening method is remarkable.