Performance Study On Steel Frame-self-centering Braced Tube Structure Under The Action Of Earthquake And Wind

High-performance structure with self-centering braces has a long lifecycle,which is likely to suffer from the coupling action of earthquake and wind during its service period.The traditional structural design method mainly considers the effect of a single disaster,ignoring the coupling action of earthquake and wind.Once the coupling of earthquake and wind occurs,it will put forward higher requirements on structural performance.In this paper,the wind time histories at different heights with different return periods are simulated based on an auto-regressive model and combined with earthquakes with different peak ground accelerations(PGAs)to study the performance of a 50-storey steel frame braced tube structure with pre-pressed spring self-centering energy dissipation(PS-SCED)braces,which can provide the theoretical basis and technical support for the design of structure with self-centering braces under the coupling action of earthquake and wind.The main contents and conclusions are as follows:(1)The dynamic responses of steel frame-self-centering braced tube structure under the action of earthquake alone with different intensities and under the simultaneous actions of earthquake and wind with return periods of one year,ten years and fifty years are respectively studied.The results indicate that under the simultaneous actions of earthquake and wind,the increase of wind load intensity has no significant effect on structural interstorey drift ratio which is mainly influenced by earthquake intensity.As wind load intensity increases,the concentration degree of structural interstorey drift decreases.As earthquake intensity decreases,the effect of wind load on the structural base shear force is more significant,and compared with the action of earthquake alone,the simultaneous actions of earthquake with the PGA of 0.7 m/s~2 and wind with a return period of fifty years increase the maximum base shear force of structure by 54.7%.When subjected to the simultaneous actions of earthquake and wind,the PS-SCED braces dissipate energy sufficiently to effectively protect the structure,and structural residual deformation is reduced obviously due to their excellent self-centering behavior.(2)The damage of beams and columns and global damage of steel frame-self-centering braced tube structure under the action of earthquake alone with different intensities and under the simultaneous actions of earthquake and wind with a return period of fifty years are analyzed.The results indicate that under the action of earthquake alone and under the simultaneous actions of earthquake and wind,the beams in the braced tube are damaged earlier than those in the frame,and with the increase of earthquake intensity,the damage of the columns in the braced tube develops faster than that in the frame.Compared with the action of earthquake alone,the simultaneous actions of earthquake and wind increase the global damage of structure,and when the PGA is 10 m/s~2,the increment of structural global damage value under the simultaneous actions of earthquake and wind is 2.5 times that when the PGA is 5.88 m/s~2,indicating that as earthquake intensity increases,the amplification influence of the simultaneous action of wind load on the structural global damage increases gradually.The residual deformation and damage development of the most severely damaged members of structure under the successive actions of earthquake with different intensities and wind with a return period of fifty years are studied.The results show that the wind load increases the average value of the maximum residual deformation ratio of seismic damaged structure under seven ground motions.However,the wind load has less influence on the damage state of the most severely damaged member of seismic damaged structure.(3)On the premise of retaining the first stiffness and the activation force of PS-SCED braces,the ratio of the second stiffness to the first stiffness of brace is defined asη,and the ratio of pre-pressed force to friction force of brace is defined asδ,and the influence law of design parameters of braces on the performances of structure is studied under the simultaneous actions of earthquake and wind with return periods of one year,ten years and fifty years respectively.The results show that increasing theηof braces and decreasing theδof braces can make the overall deformation of structure more uniform and the maximum interstorey drift ratio of structure smaller.Increasing theηof braces can also reduce the maximum residual deformation ratio of structure,and under the simultaneous actions of earthquake and wind with a return period of fifty years,when theηof braces are 0.02 and 0.15,the maximum residual deformation ratios of structure are 0.150%and 0.141%,respectively.Decreasing theδof braces can increase the proportion of energy dissipation of braces to the total energy dissipation of the structure.