钢储罐在撞击荷载作用下的结构响应与破坏模式

Structural response and failure mode of steel tanks under impact loading

为了求解大型立式钢储罐结构在遭受偶然撞击荷载作用下的结构响应和破坏模式,建立了壳体撞击下考虑碰撞接触的有限元模型,分析了撞击作用下典型钢储罐的响应过程,包括变形模式、应变分布和塑性铰线分布等;对不同撞击物速度、储罐径厚比和储罐高径比时,钢储罐的变形分布和能量变化进行参数分析;并基于参数分析结果,探讨了钢储罐的三类失效模式及其变化规律。结果表明:钢储罐在撞击作用下的主要变形区域近似呈三角形,以撞击点为中心可分为3个小三角形,部分外边界处出现正、负塑性铰线;储罐最大残余变形和撞击平均力随撞击物冲量增大呈线性增大,随高径比增大总体呈减小趋势;当半径不变、径厚比增大时,罐壁最大残余变形增大而吸能能力减小;当壁厚不变、径厚比增大时,两者均变化不大。随撞击物质量和速度的增大,储罐在撞击作用下依次出现局部失效、整体失效和破裂失效,其中局部失效最易出现;整体失效时,变形区域较大且端部约束减弱导致整体丧失承载;破裂失效时,撞击处罐壁来不及变形扩散和吸能即已达到失效应变。

In order to study the structural response and failure mode of large vertical steel storage tanks subjected to accidental impact loading,the finite element model of the shell considering collision-contact under impact was established and the response process of a typical steel tank under impact was analyzed,including the deformation mode,strain distribution and plastic hinge line.Then the deformation distribution and energy change of steel tank under different impactor velocities,tank radius-to-thickness ratios and tank height-to-radius ratios were analyzed.Based on the results of parametric analysis,three types of failure modes for steel tanks and the change rules were discussed.The results show that the main deformation region of the steel tank under impact is approximately triangular,which can be divided into three small triangles with the impact point as the center,and part of the outer boundaries appear positive and negative plastic hinge lines.The maximum residual deformation and average impact force of the tank increase linearly with the increase of impactor impulse,and decrease with the increase of height-to-radius ratio.When the radius-to-thickness ratio increases with constant tank radius,the maximum residual deformation of the tank wall increases while the energy absorption capacity decreases.When the radius-to-thickness ratio increases with constant tank thickness,both of them have little change.With the increase of the mass and velocity of the impactor,the local failure,whole failure mode and rupture failure mode of the tank appear successively under the impact,and the local failure is the most common.For the whole failure mode,the deformation region is relatively large and the end constraint is weakened leading to the loss of the whole bearing capacity.For the rupture failure mode,the tank wall at the impact has reached the failure strain before dissipating enough energy through deformation diffusion.