Study On Performance-based Seismic Design Method Of High-strength Steel Framed-tube Structures With H-section Replaceable Links

In view of the traditional steel framed tube structure’s poor energy dissipation capacity and the difficulty of post-earthquake repair under intense earthquakes loads,high-strength steel framed-tube structures with H-section replaceable link(HSS-SFTRSL)was proposed,which combines the excellent energy dissipation capacity and easy repairability of the replaceable shear links、large lateral stiffness and small residual deformation of steel framed-tube structures、high carrying capacity of high-strength steel.The mid-span position of the spandrel beams are reasonably provided with replaceable shear links that is easy to replace.The shear links are made of steel with a lower yield point steel that have great ductility,and the remaining components are made of highstrength steel.In order to study the proposed,the following study work were conducted:Firstly,the HSS-SFT-RSL prototype structures with three different layers was finely designed using traditional design methods,in accordance with the design principles of the current code,and their static elastoplastic analysis was performed.The results show that a rationally-designed HSS-SFT-RSL is a typical dual structural system,which has ideal yield sequence and overall failure mode.Each component maintains elasticity under frequent earthquakes;the shear links of some floors as the first earthquake resistant line began to enter plasticity and dissipate seismic energy under design earthquakes serves;shear links of all storys can participate in energy dissipation under rare earthquakes.When the maximum story drift of the structures reaches 1/50,the spandrel beam without links serves as the second earthquake resistant line began to appear plastic hinges.At the extreme points,structural plastic damage was concentrated in the shear links and spandrel beams,while almost no plastic hinge occured at the bottom of the columns.Secondly,considering the story number,the velocity pulse effect of near-field motions,and the acceleration cumulative effect of far-field motions,the dynamic elastoplastic analysis method was used to obtain the story shear distribution of HSS-SFTRSL structure with ideal yield mode under elastoplastic state.The law of force distribution,based on the exponential distribution model,gives the elastoplastic layer shear force distribution formula of HSS-SFT-RSL structure under near-field and far-field earthquakes.By comparison,the structure shows that the near and far field vibrations have a great effect on the story shear force distribution of the HSS-SFT-RSL structures,and it is necessary to distinguish them in the design.It can provide basis for the performance-based design method of HSS-SFT-RSL structures.Thirdly,based on the principle of energy balance,taking the ideal overall failure mode and target displacement as performance targets,the nonlinear behavior of the two earthquake resistant lines under predetermined ground motions was considered respectively,and the performance-based plastic design of the HSS-SFT-RSL structure was proposed.Analysis shows that the HSS-SFT-RSL structure designed using the PBPD method present good seismic performance and the structure shows the expected overall failure mode,which is in line with the seismic design of "multiple lines of defense" and "strong columns and weak beams";under rare-level earthquakes,shear links of each layer can participate in energy consumption,the story drifts are uniform along the height,and the story residual drifts is small,which can realize the replacement of shear links,which is beneficial to fast recovery of structural functions after earthquakes;After introducing the story shear distribution mode of the HSS-SFT-RSL structures in the elastoplastic state,the design story shear force obtained by the PBPD method can accurately predict the structure’s internal force distribution and demand in the elastoplastic phase.Compared with the traditional design method,the PBPD method can achieve the predetermined performance target without complicated iteration and calculation.Finally,under the same design conditions,three sets of high-strength steel frametube structures with replaceable shear links(HSS-SFT-RSL)and common steel frametube structures with replaceable shear links(CS-SFT-RSL)was subjected to static elastoplastic analysis and dynamic elastoplastic time history analysis,respectively,and the lateral stiffness,bearing capacity,failure mode,and layer of the two were compared.Lateral displacement and residual deformation distribution between layers and the amount of steel used.The results show that the PBPD method can ensure that both achieve the ideal failure mode;the bearing capacity of the HSS-SFT-RSL structures is higher than that of the CS-SFT-RSL structures,but the lateral stiffness is slightly lower;although the story drifts and residual story drifts of HSS-SFT-RSL structures are slightly larger than the latter,but both meet the code and the replaceable limits of shear links,both of which have considerable post-seismic repair capabilities;HSS-SFT-RSL structures can save about 16% steel compared to CS-SFT-RSL structures.