【摘要】 宁夏超高钢结构电视塔结构高度216m,桅杆长度104m。建筑体型为底部小、上部大、中部略呈细腰形且设计有三段楼层共计28层的花瓶状形体。楼层不连续分布导致结构质量和侧向刚度沿竖向分布不均匀,结构几何形式复杂,对抗震要求高。首先,使用ANSYS分析研究结构的动力特性。同时,针对结构固有频率,将ANSYS和SAP2000计算结果进行了比较。结果表明,结构的扭转效应明显,第三和第八阶振型是以扭转为主的振型,结构扭平周期比满足我国规范要求,但数值偏高。接着,分别采用振型分解反应谱法和动力时程法计算多遇地震作用下结构的多维弹性地震响应。数值结果表明,动力时程分析能够更清晰地反映结构桅杆的鞭稍效应。因此,在评估此类复杂形体建筑的抗震性能时,应综合评定反应谱和时程法的计算结果。多维地震作用下结构的变形指标符合国家现行相关规范要求。最后,对结构进行了8度(0.2g)、8度(0.3g)和9度三种设防烈度罕遇地震作用下结构的弹塑性动力时程分析,以检查结构变形指标与塑性发展情况。结果表明,结构变形指标符合国家现行相关规范要求,结构的最危险部位在中部楼层段(细腰段)。因此,结构满足"小震不坏,中震可修,大震不倒"的抗震设防要求。通过大量计算分析与比较,综合出了许多有益的结论与建议,为该实际工程或类似工程的抗震设计提供参考依据。此外,计算分析方法对于应用有限元软件计算复杂几何结构具有借鉴价值。更多还原

【Abstract】 The structural height and antenna mast height of Ningxia TV tower(NXTVT) is 216m and 104m,respectively.The shape of NXTVT resembles a vase with small-bottom,large-top,and slender-waist-middle,it consists of three storey segments with 28 floors in total.The discontinuous arrangement of floors leads to the uneven distribution of structural mass and lateral stiffness.Thus,this structure with complex geometry requires a high demand of seismic performance.Firstly,ANSYS code was employed to analyze the dynamic characteristics of NXTVT.Simultaneously,for the purpose of comparison,the results of the structural natural frequencies using SAP2000 code were also taken into account.The numerical results indicated that the 3rd and 8th modes of the structure are torsional ones,and furthermore the torsional effect is considerably significant;the ratio of the 1st torsional modal period to the 1st translational modal period meets the requirement of Chinese code,but it is close to the limiting value.Then,the responses of this building under frequent earthquakes were analyzed using both the mode superposition response spectrum method and the time-history one,respectively.The whiplash effect could be revealed clearly through the time-history analysis.Accordingly,the seismic performance should be comprehensively evaluated based on the results of the two methods mentioned above.Under multi-dimensional earthquakes,the structural deformation met the requirements of Chiese code for seismic design of buildings.Finally,the responses of the structure under 8°(0.2g),8°(0.3g),and 9° rare earthquakes were analyzed using the dynamic elasto-plastic time-history method in order to check both the deformation indices and development of the plastic zone of the structure.The numerical results demonstrated that the inelastic deformation meets the requirements of Chinese code for seismic design of buildings;likewise the middle storey segment with slender-waist is the weakest part;therefore,Ningxia TV tower can meet the requirements of no damage under small earthquakes,repairable damages under middle earthquakes,and no collapse under rare strong earthquakes.Through extensive numerical analysis and comparisons,the conclusions obtained herein were useful for the earthquake-resistant design of NXTVT or similar projects.Additionally,the analysis approaches were a reference for calculation of structures with complex geometry utilizing commercial finite element program.更多还原