| How to ensure the safety of structures under strong earthquakes is a challenging task for the engineering community.In recent years,vibration reduction technology has been considered as a means to effectively control the vibration response of structures.However,the small story displacement of rigid structure under earthquakes limits the motion displacement of the damper,which makes the hysteretic energy dissipation effect of the damper under the traditional installation form(Such as chevron brace or diagonal brace)less obvious.Therefore,the research and development of new damping system with high energy consumption effect is one of the key problems to be solved urgently in the scientific and engineering circles.Based on the National Key Research and Development Project “Earthquake disaster mechanism and seismic mitigation and isolation technology for large key engineering structures”(No.2017YFC1500705)and the National Natural Science Foundation Project “Research on performance of structural passive control system based on monitoring data”(No.51838006),this paper proposes two new vibration reduction systems of frame structures with high energy consumption effect from the aspects of theoretical analysis,numerical simulation and experimental research.Their theoretical mechanism,hysteresis performance,displacement amplification characteristics,energy dissipation and vibration reduction effect are systematically studied.The main conclusions are as follows:(1)Two new types of toggle-brace-damper systems are proposed,namely,the upper toggle-brace-damper(UTBD)system and the lower toggle-brace-damper(LTBD)system.The corresponding theoretical mechanism model is established,the displacement amplification factor is derived,and the key performance parameters that affect the hysteretic energy consumption of dampers in the UTBD system and LTBD system are clarified.The effectiveness of the theoretical model of the new types of toggle-brace-damper systems is verified by the corresponding finite element model.Compared with several common brace-damper systems,the remarkable hysteretic performance and displacement amplification characteristics of the new types of toggle-brace-damper systems are verified.(2)In view of the technical characteristics that metal dampers such as traditional X-shaped steel plates and shear-shaped steel plates cannot be installed and used in the UTBD and LTBD systems,a new type of butterfly-liked metal damper(BLMD)with large stroke,high energy consumption and assembly is proposed in this paper,which is suitable for the UTBD and LTBD systems.The hysteretic energy dissipation mechanism of BLMD is proved by means of numerical simulation and experimental verification.The effects of the thickness,width,length and height of the U-shaped energy dissipation components on the equivalent stiffness and equivalent damping ratio of the BLMD are clarified.The theoretical hysteretic model of the new BLMD is derived and compared with the experimental results.(3)Through several groups of frame tests,the hysteretic energy dissipation characteristics of the UTBD system with BLMDs under quasi-static cyclic load and the displacement amplification characteristics of additional dampers are discussed.Compared with the test results of traditional diagonal brace-damper(DBD)system and traditional toggle brace-damper(TTBD)system,the advantages of the UTBD system in hysteretic energy consumption are verified.The hysteretic energy dissipation characteristics of BLMDs with different geometric parameters in the UTBD system are systematically studied by finite element simulation models.(4)The shaking table tests of the four story steel frames with vibration damping systems are carried out,and the displacement time history response characteristics and the control effect of the vibration reduction systems of the four story steel frame structures under different seismic waves are discussed.The corresponding three-dimensional numerical simulation models are established,and the effectiveness of the numerical simulation models are verified by the experimental results.Taking the numerical simulation model of 15 story reinforced concrete frame structure as an example,the advantages of the UTBD system compared with the DBD and TTBD systems are systematically analyzed.Through the above research,the main conclusions are as follows:(1)Both UTBD system and LTBD system have significant displacement amplification characteristics,and their theoretical results are in good agreement with the finite element results.Compared with the traditional toggle-brace-danper systems,the displacement amplification factors of the UTBD system and LTBD system are 3.49 times and 2.75 times respectively,which can significantly enhance the hysteretic energy dissipation characteristics of the damper.(2)The proposed BLMD has good ductility and stable hysteretic energy dissipation characteristics,which is easy to assemble and replace,and can be used as a damper energy dissipation device in structures.(3)The test results of frames show that the BLMD installed in the UTBD system has the largest displacement,which is 1.35 times and 2.19 times that of the TTBD system and the DBD system respectively.Those test results verifies the correctness of the theoretical mechanism and numerical analysis on the UTBD system.(4)The shaking table test results show that compared with the structures without damper,with DBD system and with TTBD system,the maximum inter story displacement angle of the UTBD system is reduced by 96.8%,93.52% and 91.08%,respectively.The structures with the UTBD system has the best displacement control effect,and can significantly reduce the inter story displacement angle response of the structure. |
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