| In order to improve the seismic performance of the precast concrete frame and based on the concept of the structure resilience,a new self-centering post-tensioned precast prestressed concrete frames with Bamboo-shaped Buckling-Restrained Brace(BBRB)devices(SC-PCBD)connection is recently proposed.During the earthquake,the prestressed tendons provide the self-centering capability and the BBRB provides the energy-dissipation ability.The structural damage mainly concentrates on the BBRB.In this paper,the experimental study on the behavior of the BBRB is carried out first,together with the finite element analysis.On the basis of the results of the analysis of BBRB,the theoretical and experimental study on the behavior of SC-PCBD connection was continued.The main contents are as follows:(1)Different kinds of energy dissipating bars which used in connection models of precast concrete structure are thoroughly introduced,together with their respective advantages and disadvantages.According to the requirements of easy installation and replacement,a new type of post-tensioned concrete frame connection based on the BBRB was proposed and summarized its characteristics.(2)In order to study the property of BBRB,14 BBRB specimens were subjected to reversed low-cycle load.Several parameters which have a significant impact on the behavior of BBRB were analyzed,such as the length of segment,the length of slub,the number of slubs and loading patterns.The experimental results show that BBRB has a full hysteresis curve under reciprocating loads and cumulative plastic deformation of BBRB is far more than the requirements of AISC specification.So BBRB has good capacity of energy dissipation and fatigue performance.(3)Finite element software Abaqus was used to carry out numerical simulation for BBRB.Results show that analysis model based on Abaqus can be applied to non-linear analysis and of good precision.Combined with the results of BBRB in the experiment,numerical simulation of BBRB with the difference of the length of segment,the length of slub,the number of slubs,the initial defect,the friction and the clearance was carried out.At the same time,the evolution law of the lateral displacement of the segment of BBRB with loading process was studied on the basis of the simplified model.The accuracy of the simplified model was verified by comparing results from the simplified model with the experimental results.(4)The hysteretic model of the SC-PCBD connection was proposed which is the superposition of the BD nonlinear elastic model provided by the prestress and the BD bilinear elastoplastic model resulted from BBRB.On the basis of theoretical analysis,one full-scale SC-PCBD connection was then subjected to reversed low-cyclic load.The experimental results show that SC-PCBD connection has good self-centered ability and energy dissipation capacity and it is easy to repair after the earthquake.(5)Aiming at the problem that the beam longitudinal reinforcement was not anchored into the column,the finite element software OpenSEES was used to solve the problem of mechanical behavior simulation of beam-column connection and the nonlinear analysis model of the SC-PCBD connection was proposed.The simulated hysteresis curve is in good agreement with the experimental results.The parameter analysis includes following factors to the performance of SC-PCBD:the arrangement of BBRB,the total force of prestressed tendons,the concrete strength,the length of unbonded prestressed tendons,the cross-sectional area of BBRB.Recommended values of above parameters were provided. |
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