Study On Seismic Behavior Of D-type Eccentrically Braced Steel Frames With Low Yield Replaceable Energy-dissipating Beams

The design point of the eccentrically braced structure system lies in the energy-dissipation beam.The traditional eccentric support structure energy-dissipation beam and the beam are a whole.After the earthquake damage,it brings great difficulty to the repair and replacement of the energy-dissipation beam.Thus,the concept of an replaceable energy-dissipation beam eccentric support structure is proposed.However,in the replaceable energy-dissipation beam eccentric support,in order to allow the energy-dissipation beam to preferentially yield energy dissipation and achieve the purpose of the plastic hinge moving out,and prevent other components from being damaged,the energy-dissipation beam size is often reduced relative to the beam,so that the stiffness of the structure is reduced,the bearing capacity is decreased,and The beam and energy-dissipation beam are not the same size,which is not conducive to construction.In order to solve the above problems,the concept of replaceable low-yield energy-dissipation beam is proposed,which is to change the energy-dissipation beam material to low-yield point steel,so as to ensure that the energy-dissipation beam size is consistent with the beam and under earthquake action.The low yield energy beam can give priority to yielding energy dissipation and achieve outward moving of plastic hinge.D-type eccentric support is a commonly used form of eccentric support structure.The paper will systematically study the D-type eccentric support structure of low-yield replaceable energy-dissipation beam.In this paper,the new D-type eccentric support structure proposed by YJKS and ABAQUS finite element nonlinear analysis software is analyzed and studied as follows:(1)Using the YJKS software to build a 14-layer D-type eccentrically braced steel frame model according to the actual working conditions,and verifying the bearing capacity of the steel frame under the action of medium and large earthquakes,and determining the size of the traditional D-type eccentric support members,ABAQUS software prepares a new D-type eccentric support structure finite element model.(2)A new type D eccentric support structure was established by ABAQUS software.The feasibility study of the new structure under the action of small earthquake,medium earthquake and large earthquake was carried out to determine whether the new D-type eccentric support structure is feasible under earthquake action.Through nonlinear analysis,it is concluded that the new structure meets the requirements of the standard "small earthquake is not bad,medium earthquake can be repaired,large earthquake does not fall" seismic target.(3)The factors affecting the seismic performance of the new D-type eccentric support structure were studied.Four groups of 12 shear-type eccentric supports were established by ABAQUS,and each model corresponds to an influencing factor.The influencing factors include the relative length of the energy-dissipation beam sections,the spacing of the stiffeners in the energy-dissipation beam sections,the web thickness of the energy-dissipation beam sections,and the energy-dissipation beam sections using different yield points.Throughsimulation,the following conclusions are drawn: the longer the energy-dissipation beam segment,the structural energy dissipation capacity is gradually reduced,and the structural stiffness,ultimate bearing capacity,ductility coefficient and plastic rotation angle are gradually reduced.The larger the spacing of stiffeners on the energy-dissipation beam section,the structural rigidity and hysteresis ability are basically unchanged,but the structural ductility coefficient and plastic rotation angle are gradually increased,and the structural rotation ability is slightly increased.The thickness of the web of the energy-dissipation beam section increases,the energy consumption capacity increases gradually,and the structural stiffness,ultimate bearing capacity,ductility coefficient,and plastic angle increase.When the yield stress of the energy-dissipation beam section steel increases within a certain range(100MPa~225MPa),the structural stiffness is basically unchanged,and the hysteretic behavior,ultimate bearing capacity,ductility and plastic angle are gradually increased,and the structural energy consumption capacity is gradually increased.(4)Finally,the new eccentric support structure is added to increase the composite slab(concrete and profiled steel),the crack process development of the composite slab,and the impact of the composite slab on the seismic performance of the new structure.Through analysis and research,the following conclusions are drawn: the concrete composite floor slab crack is firstly formed at the junction between the left energy-dissipation beam section and the beam section,located near the end plate,and then the right-hand energy-dissipation beam section meets the beam section,and the concrete is also Cracks were formed and two complete fracture zones were formed,and the location of cracks in the new eccentric support structure floor was determined,which laid a theoretical foundation for future slab repair and reinforcement work.After the combination of the slabs is increased,the stiffness and ultimate bearing capacity of the new eccentric support structure increase,the structural viscous damping coefficient decreases by 4.99%,the hysteretic behavior and ductility decrease,the plastic rotation angle decreases by 5.03%,and the rotation capacity decreases,but the decrease is Not large,has little effect on the seismic performance of the new D-type eccentric support structure.