| The post-tensioned frame system is to connect the beam and column together by prestressing force,so that the post-tensioned beam-column joint has the characteristics of small residual deformation and excellent seismic performance,which can realize the restorability of structural functions after an earthquake.Compared with post-tensioned concrete structure,the studies on the post-tensioned timber structures is in the initial stage,which still needs further research.In this paper,considering the characteristics of wood material and focusing on the post-tensioned timber beam-column joint,the experimental research and numerical analysis are carried out from the two aspects of the local bearing reinforcement and the connection of energy dissipation devices.The main research contents are as follows:(1)Due to the influence of the wood anisotropy,the local bearing areas of the beam-column joint need to be reinforced.Therefore,five post-tensioned timber beamcolumn joints were designed to analyze load displacement response,the deformation and failure mode of connection,prestress loss and neutral axis position through the quasi-static loading test.The test results demonstrated that the post-tensioned timber beam-column joints performed stable bearing capacity.The reinforcement of "steel plate and screws" combination could significantly improve the strength and initial stiffness of the joint and reduce the loss of prestress.(2)In order to improve the energy dissipation capacity of post-tensioned timber beam-column joint,the additional energy dissipaters are set up on the two sides of the joint.Three post-tensioned timber beam-column joints were designed with two types of connection in energy dissipation devices.These hybrid beam-column joints were tested to evaluate the load displacement response,the deformation mode,the prestress loss,the neutral axis position and the equivalent viscous damping,which was used to analyze the influence of different reinforcements and connecting ways of energy dissipation devices on the joint performance.The test results indicated that the hybrid joint with additional partially restrained energy dissipaters fixed by steel plate had the characteristics of excellent energy dissipation capability,small residual deformation and controllable prestress loss.The specimens performed stable bearing capacity without strength degradation during the loading process,and the joints could maintain sufficient loading capacity and energy consumption capacity under the direct secondary loading without repair.(3)Based on ABAQUS and Open Sees software,the three-dimensional refined numerical model and two-dimensional model of the post-tensioned timber beamcolumn joint were established respectively,and the numerical models were corrected by the test results;combined with the parametric analysis,several factors influencing the joint performance were studied including the size of the steel plate inside the column,the initial prestress and the number of partially restrained energy dissipaters in order to provide the basis for the design in self-centering timber frames. |
