考虑土-结构动力相互作用的冷却塔地震响应分析

发布时间：2018-03-06 20:36

本文选题：冷却塔结构　切入点：地震响应分析　出处：《振动与冲击》2016年23期 　论文类型：期刊论文

【摘要】：大型高耸钢筋混凝土冷却塔属于典型的风敏感型结构,近年来在地震、飞机撞击、爆破等极端外部作用下动力响应研究也得到了工程界的广泛关注。土-结构动力相互作用效应(Soil Structure Interaction,SSI)对于大坝、桥梁等类型工程结构地震响应的影响研究成果较为丰富,而对冷却塔结构体系的影响程度方面很少涉及。依据弹性波动理论结合有限单元法,建立和推导了考虑土-结构动力相互作用的三维黏弹性人工边界模型和公式,并通过半空间自由场模型验证该地震动输入方法的准确性。以国内实际工程项目——某火电厂大型冷却塔为研究背景,以通用有限元程序ANSYS为平台,分别建立了冷却塔刚性地基模型、无质量地基模型和黏弹性人工边界模型,开展模态分析及弹性时程分析,研究不同计算模型相应的动力特性及内力变化,探讨了土-结构动力相互作用的影响规律。研究结果表明:考虑刚性地基,冷却塔结构体系自振频率分布十分密集,绝大多数振型为环向谐波和子午向谐波组合的局部振型;考虑弹性地基后,结构的自振频率略有降低,整体振型较早出现。通过时程分析可知,采用黏弹性人工边界模型,考虑无限地基辐射阻尼效应,与刚性地基模型相比,塔筒的绝对加速度最大值降低43.4%,塔筒沿子午向弯矩轴力幅值降低约50%,而环向内力却均显著提高,X支柱内力幅值降低约20%~50%.因此,在进行冷却塔地震响应分析时,土-结构动力相互作用的影响不可忽视。
[Abstract]:The large high-rise reinforced concrete cooling tower is a typical wind-sensitive structure. In recent years, during earthquakes, aircraft impact, The study of dynamic response under extreme external action, such as blasting, has also received extensive attention in engineering circles. The effect of soil Structure interaction on seismic response of dams, bridges and other types of engineering structures has been studied in this paper, and the results are relatively rich in the study of the effects of soil-structure dynamic interaction effect on the seismic response of structures such as dams, bridges and other types of structures. Based on elastic wave theory and finite element method, a three-dimensional viscoelastic artificial boundary model and formula considering soil-structure dynamic interaction are established and derived. The accuracy of the local vibration input method is verified by the half-space free field model. Taking the domestic practical project, a large cooling tower of a thermal power plant, as the research background, the universal finite element program ANSYS is used as the platform. The rigid foundation model of cooling tower, the massless foundation model and the viscoelastic artificial boundary model are established respectively. Modal analysis and elastic time history analysis are carried out to study the corresponding dynamic characteristics and internal force changes of different calculation models. The influence law of soil-structure dynamic interaction is discussed. The results show that the natural vibration frequency distribution of cooling tower structure system is very dense considering rigid foundation, and the majority of vibration modes are local mode of combination of toroidal harmonic and meridional harmonic. Considering the elastic foundation, the natural vibration frequency of the structure decreases slightly, and the whole vibration mode appears earlier. Through the time history analysis, it can be seen that considering the radiation damping effect of infinite foundation, the viscoelastic artificial boundary model is compared with the rigid foundation model. The maximum absolute acceleration of the tower tube is reduced by 43.4 parts, the axial force amplitude along the meridional moment of the tower tube is reduced by about 50, but the internal force amplitude of the annular force is significantly increased by about 20 / 500.Therefore, in the analysis of the seismic response of the cooling tower, The influence of soil-structure dynamic interaction can not be ignored.
【作者单位】：西安理工大学水利水电学院;西安理工大学土木建筑工程学院;中国水利水电科学研究院工程抗震研究中心;
【基金】：国家自然科学基金(51179162)
【分类号】：TU311.3

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