【作者】 王喆；

【导师】 刘艳辉；

【作者基本信息】 西南交通大学 ， 建筑与土木工程（专业学位）， 2019， 硕士

【摘要】 相比于圆钢管混凝土结构,方钢管混凝土结构在节点施工方面存在诸多优势,因此越来越多地被应用到实际工程当中。结构在使用过程可能遭受车辆、船舶等意外冲击作用,统计显示,这种对结构的冲击作用的角度往往具有随机性。而方钢管混凝土结构横截面并非是极对称的,所以不同冲击角度的冲击作用使结构产生的动力响应也不尽相同。本文从试验、有限元模拟和理论分析三个方面研究了不同冲击角度冲击荷载作用下方钢管混凝土结构的动力响应,主要研究内容如下:1.进行了落锤冲击试验,研究了冲击角度为0°时冲击高度、钢管壁厚、轴压力以及边界条件对方钢管混凝土结构动力响应的影响。试验结果表明方钢管混凝土试件在冲击位置四周会出现较大鼓曲变形,减弱了试件整体刚度,不利于结构抵抗冲击作用;试件整体刚度(包括约束条件影响和试件截面性质影响)对动力响应位移幅值的影响较大,刚度越大,位移越小。2.根据实际中常见的冲击形式,采用经试验验证的参数,建立了不同冲击角度冲击荷载作用下简化的方钢管混凝土整体变形模型和角部损伤模型。有限元模型计算结果显示,方钢管混凝土结构在不同冲击角度冲击荷载作用下,沿纵向的动力响应规律是相同的;冲击体直接冲击方钢管混凝土结构角部时,很可能导致角部局部破坏并发生较大局部变形,削弱结构整体刚度;当冲击能量相同而冲击动量不同时,冲击动量越小,冲击持时越短,材料应变率效应越明显,从而使冲击力峰值增大,挠度减小。3.通过移行铰理论得到两端固支梁在任意位置侧向冲击荷载作用下最大位移与梁横截面塑性极限弯矩成反比的关系,并推导了不同冲击角度方钢管混凝土结构截面塑性极限弯矩的计算表达式。计算结果表明,方钢管混凝土结构截面塑性极限弯矩随冲击角度的增大而减小,故其在冲击荷载作用下最大位移随冲击角度增大而增大。4.通过对比有限元计算结果与理论推导结果,发现限制方钢管局部鼓曲变形的局部约束可以有效提高方钢管混凝土结构抗冲击能力。更多还原

【Abstract】 Compared with circular concrete-filled steel tubular members,Square concrete-filled steel tubular members has many advantages in joint construction,so it is increasingly being applied in practical engineering.The structures may be subjected to accidental impacts by vehicles and ships.Statistics show that the angle of impacting on the structure is often random.However,the cross-section of concrete-filled square steel tubular structure is not extremely symmetrical,so the dynamic response of the structures varies with different angles of impacting.Therefore,it is necessary to study the relationship between the dynamic response of square concrete-filled steel tubular members and the angle of impact load.In this paper,the dynamic response of square concrete-filled steel tubular(CFST)members subjected to impact loads at different impact angles is studied from three aspects: experiment,finite element simulation and theoretical analysis.The main research contents are as follows:1.Drop-weight impact tests were carried out to study the effects of impact height,wall thickness of steel tube,axial pressure and boundary conditions on the dynamic response of square concrete-filled steel tubular structures with impact angle of 0 degrees.The test results show that the buckling deformation of square concrete-filled steel tubular specimens around the impact location weakens the overall stiffness of the specimens,which is not conducive to the impact resistance of the structure;the overall stiffness of the specimens(including the effects of constraints and the cross-section properties of the specimens)has a great influence on the displacement amplitude,and the greater the stiffness of the specimen is,the smaller the displacement is.2.According to the common impact forms in practice,the simplified integral deformation model and corner damage model of square concrete filled steel tubular(CFST)under impact loads with different impact angles are established by using the parameters verified by experiments.The results of finite element model calculation show that the dynamic response law along the longitudinal direction of square concrete-filled steel tubular structure under impact load at different impact angles is the same;when the impact body directly impacts the corner of square concrete-filled steel tubular structure,it is likely to cause local damage and large local deformation in the impact area,weakening the overall stiffness of the structure;when the specimens are under the same impact energy,the smaller the momentum is,the shorter the impact duration is,and the more obvious the strain rate effect is,so that the peak value of impact force increases and the maximum displacement decreases.3.Based on the theory of transition hinge,the inverse relationship between the maximum displacement of the clamped-clamped beam and the plastic ultimate moment of the cross-section of the beam under lateral impact load at any position is obtained,and the formulas for calculating the plastic ultimate moment of the cross-section of square concrete-filled steel tubular structures at different impact angles are derived.The calculation results show that the plastic ultimate moment of concrete filled square steel tubular structure decreases with the increase of impact angle,so its maximum displacement increases with the increase of impact angle.4.By comparing the results of finite element calculation and theoretical derivation,it is found that the local restraint of local buckling deformation of square steel tube can effectively improve the impact resistance of concrete filled square steel tube structures.更多还原