风荷载作用下LNG储罐混凝土外罐力学性能分析

Mechanical behavior of LNG concrete outer tank under wind

摘要:

为获得大型全容式LNG储罐混凝土外罐在风荷载作用下的响应特性,以有限元软件ANSYS为分析平台,针对一160 000 m³ LNG储罐实际工程建立了静力风荷载及顺风向脉动风荷载作用下的精细化有限元模型.通过对比国外学者提出的傅里叶解析式表达圆柱体表面的风压分布和中国《建筑结构荷载规范》给出的旋转壳体周向体型系数,以及中美规范关于风压高度变化系数的规定,表明中国《建筑结构荷载规范》确定风压分布对结构影响更为不利；对比了不同风向下储罐外罐的内力及变形模拟结果,获得了各风向对储罐响应的影响程度及规律；采用拟定常假设,来流风速谱取Davenport谱,储罐外罐的风振响应分析结果表明：顺风脉动风荷载作用下,结构的位移及环向应力的变化趋势与静力风荷载作用下相近,但应力及位移的极值响应结果约为静力风荷载作用2倍;与静力荷载下储罐结构的响应结果对比表明,静力风荷载及顺风向脉动风荷载对LNG储罐混凝土外罐的受力及变形影响皆不大.

Abstract:

In order to obtain the response characteristics of LNG (liquefied natural gas) containment tanks under wind load, an accurate model of a 160 000 m³ LNG tank is established based on practical engineering. Finite element analysis via ANSYS is conducted considering static wind and along-wind vibration. Comparison is made between the Fourier series for wind pressure distribution of cylinders supposed by foreign scholars and shape coefficients for wind pressure distribution of circular section structures adopted by Chinese load code for the design of building structures. Wind pressure height coefficients are also compared between Chinese code and U.S code. It is proved that the coefficients adopted by Chinese load code are more adverse for the LNG tank. The results of deformation and stress in different wind directions are analyzed and reveals how wind directions affect the response of LNG tanks under wind load. The analysis of wind-induced response is carried out, adapting quasi-steady assumption and Davenport spectrum. The results show that under along-wind fluctuating wind load, the changing trend of deformation and stress is close to the result under static wind but the extreme response is twice. Compared to the response under other static loads, static wind load and along-wind fluctuating wind load have little influence on LNG tanks.