| Prefabricated buildings will be the development direction of building industrialization,and our country is also vigorously promoting the development and application of prefabricated buildings on the policy,beginning to carry out pilot requirement of assembly rate.What can be foreseen is that the prefabricated building will become the mainstream building type in the future.The post-tensioned prefabricated concrete structure adopts dry connections which is very potential and easy to construct.Full prefabrication is easier to come true as for a dry-connection structure and higher efficiency can be obtained,which means the industrialization of building construction is more feasible.Besides,the post-tensioned joint is usually assembled by flexible connections which have a more reasonable mechanical behavior,which means the post-tensioned joint is easier to design with the performance-based design method and has a higher seismic performance level of structure.What's more,the kind of joint is more environmentalfriendly and energy-saving,conforming to the developing trend of the future.Based on the research status of existing post-tensioned prefabricated concrete beam-column joint,the thesis put forward a new Post-tensioned Energy Dissipation joint(Abbreviated to NPTED).NPTED joint comprises a new dissipative damper for joints which is called Rhombus Driving Friction Damper(Abbreviated to RDF Damper).NPTED joints adopt the method of slotting the beam end to obtain a longer arm of force,coupled with the architectural function within the joint not being intervened.Besides,a kind of quasi joggle is used within beam-column interface in order to make sure the joint stays safe even if failure happened to the tendon,which means the joint can satisfy the requirement of failure safety.RDF damper adopted within the joint is different from some ordinary steel plate friction damper.Instead,RDF damper makes use of rhombic transmission rod assembly to drive the two ends of the friction plate to move.The existence of Rhombus Amplification Mechanism makes RDF damper dissipate more energy within relatively small rotation.Based on the facts and consideration above mentioned,the main research contents and conclusions of this paper are as follows:(1)RDF damper and NPTED joint are put forward.Post-tensioned prefabricated concrete beamcolumn joints with energy dissipation devices make use of peculiar rocking mechanism within beamcolumn interface to dissipate energy,which means the quantity of dissipated energy is directly related to how big the opening is.However,the stability requirement of the joint makes the joint unable to produce an excessive opening,and a limited opening is adverse on energy dissipation.Therefore,it is necessary to find out a way to achieve greater energy dissipation when the opening is small.It is showed in the study that on the condition of a small opening,increasing the displacement is a feasible idea.Besides,the result of the analysis shows that slotting on the beam end is a feasible method in NPTED joint.(2)Theoretical analysis of RDF damper and NPTED joint are completed.The thesis elaborates the basic principle and effect of the Rhombus Amplification Mechanism,and deduces the practical formula and model of the device from the theoretical point of view.Besides,the thesis studies the bearing capacity formula and hysteresis theoretical model of the corresponding new joint.The RDF damper has the theoretical basis for generating a Rhombus Amplification Mechanism,which shows that it can achieve greater energy consumption under the condition of smaller beam end angular displacement.(3)The thesis makes research on RDF damper by experiments.Through the low cycle loading test of five specimens,the mechanical properties and energy dissipation characteristics of the joint under cyclic loading were studied.The parameters of the experimental study included the type of friction plate and bolt preload force.Experimental research of the RDF damper show that the damper has practical effects and can fully play the role of the rhombus transmission mechanism,which is not only theoretically feasible but also practical.(4)Numerical simulation of RDF damper and NPTED beam-column joints are done.The basic performance of the device can be obtained through experiments,but the parameters analyzed by the test are limited,and the numerical model can make up for this.Through the numerical simulation,the specific influence of various parameters of the device on the device is studied in detail,and the device is further optimized according to the result.Simulation of the joint can verify its validity and analyze its performance.The simulation results show that the RFD damper works well under various parameters and agrees well with the experimental values and theoretical values.Numerical simulation studies of NPTED beam-column joints show that the joint has the expected performance and has better energy dissipation efficiency. |
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