【作者】 杨勇；

【导师】 赵阳；

【作者基本信息】 浙江大学 ， 结构工程， 2011， 硕士

【摘要】 薄壁圆柱壳结构广泛应用于土木工程中,如储罐、筒仓、塔桅、烟囱以及管道等。建造在软土地基上的大型圆柱壳容易产生各种沉降变形,包括壳体的整体均匀沉降、整体倾斜沉降、壳体周边的不均匀沉降以及局部沉降。薄壁结构的稳定性能对沉降变形十分敏感,其中壳体周边的不均匀沉降对壳体稳定最为不利。本文希望通过试验研究考察薄壁圆柱壳在不均匀沉降下的稳定性能。本文设计、制作了一套与壳体结构初始缺陷测量系统相集成的不均匀沉降产生装置。这套不均匀沉降产生装置总共32个沉降点,通过调节32个沉降产生点处的正反螺纹可调套筒产生沉降位移,可以灵活模拟各种谐波沉降和局部沉降；同时,设计、制作了边界模拟装置,通过这套装置制作壳体模型,并很好地形成薄壁圆柱壳模型顶部边界和底部边界,能够很好地模拟浮顶壳体和固顶壳体。浮顶壳体和固顶壳体在这种状态下,可以假定薄壁圆柱壳没有初始应力,只有很小的几何初始缺陷,适用于薄壁圆柱壳的试验研究。本文利用聚酯薄膜和钢材制作试验模型,通过沉降产生装置产生谐波沉降和局部沉降,利用测量系统对试件初始几何缺陷以及试验过程中的试件变形进行精确测量,通过数据采集系统记录试验数据。对试验模型进行了非线性有限元分析,分析中直接引入实测初始几何缺陷,并且有限元结果与试验结果进行了比较。研究发现,谐波沉降作用下,浮顶壳体壳顶径向位移表现为内凹和外凸相间的波状,波数等于沉降谐波数；固顶壳体的变形形状有两种基本形式：贯穿整个高度的剪切变形和壳底局部轴向压力引起的“象脚破坏”。谐波数较小时,屈曲主要表现为贯穿整个高度的剪切变形；谐波数较大时,屈曲模态主要为壳底局部“象脚破坏”。局部沉降作用下,壳体的结构响应与不均匀沉降的周向跨度有关。更多还原

【Abstract】 Thin-walled cylindrical shell structures are widely used in civil engineering, such as tank, silo, tower mast, chimney and piping. Large cylindrical shells constructed in soft foundations are susceptible to various types of settlement deflections, including uniform settlement, planar tilt, differential settlement and localized settlement. Differential settlement of the circumference of thin-walled cylindrical shell can cause large deflections of the shell, in which the settlement beneath the shell wall leads to the most serious consequence for the tank. The paper aims to research the stability of thin-walled cylindrical shell under differential settlement.The paper designs and produces settlement generator integrated the initial imperfection measuring system of shell structure which can simulate various differential settlement at the same time. The settlement generator has 32 settlement points, which can generate settlement by adjusting the right-and-left threaded and adjustable sleeve at the location of the 32 settlement and flexibility simulate various harmonic settlement and local settlement. At the same time, the paper designs and produces boundary equipment which can make thin-walled cylindrical shell and restrict the upper boundary and the lower boundary of the shell and simulates floating-roof shells and fixed-roof shells. In this case, floating-roof shells and fixed-roof shells can be assumed that there is no initial stress and small initial geometric imperfections for experimental Study of thin-walled cylindrical shells.Melinex and metal were used to make models in this paper. Through settlement generator causing harmonic settlement and local settlement, the initial geometric . imperfection and the deflection in the experiment were conducted on the shell model by using measurement system, and the experimental data was recorded by data acquisition system. The nonlinear finite element analysis of shell model with the initial geometric imperfection was done. The nonlinear finite element analysis results were compared with the experiment results.The study finds that the displacement of floating-roof shells at the top is wave with concave and convex form and the number of the wave is equal to the number of harmonic settlement. The deformation of the fixed-roof shells takes mainly two types of forms:shearing buckling extending throughout the entire height and the elephant’s foot failure caused by the local axial stresses. When the number of harmonic settlement is small, the buckling mode is mainly shearing buckling extending throughout the entire height. When the number of harmonic settlement is big, the buckling mode is mainly the elephant’s foot failure. The response of the shells under local settlement is related with the circumferential angle of the differential settlement.更多还原