限位对框架式高塔抗震性能的影响

Effect of Displacement Limit to Seismic Performance of Framed Tall Column

基于ABAQUS有限元分析软件,建立了大长径比框架式高塔的非线性有限元模型,研究了地震作用下采用限位设计的框架式高塔结构体系的受力特点,重点分析了框架与塔体之间限位值的变化对结构体系抗震性能的影响。结果表明:在地震作用下,随着限位支架处限位值的增大,塔顶的最大位移和框架塔的最大底部剪力并未单调同步增大,其中塔顶的最大位移表现为先减小后增大、框架塔的最大底部剪力表现为增大-平稳-再增大的现象;此外,由于限位支架限位的存在,在框架与塔体碰撞的瞬间,限位处的塔体出现应力瞬间急剧放大-回落-再放大的不断反复。因此,限位值的大小和变化对框架式高塔的抗震性能具有显著的影响,设计时应充分考虑这一影响并合理确定最优限位值。

By using finite element software ABAQUS, a nonlinear finite element model of framed tall-column with large ratio of length-diameter was performed. The structural behavior of t framed tall-column under seismic excitations was studied, and the effects of displacement limit on seismic behavior of the structure system were emphatically analyzed. The analysis indicated that： under earthquake condition, when displacement limit is getting large, the maximum displacement at the top reduces first and then will increase, while the maximum shear force at the bottom of column always increases. Because of the displacement-limit, the frame and the column will collide with each other, which makes the stresses at the connection point amplified transiently tens or even hundreds of times then reversed late. As a result, effects of the displacement-limit on seismic behavior of framed high-tower should not be ignored, and the appropriate value of displacement-limit should be determined in design.