地铁车站盖挖逆作钢管立柱受力机理及工程应用

以深圳地铁11号线与6号线换乘站松岗站的盖挖逆作法施工为工程研究对象,在介绍盖挖逆作设计方案的基础上,对钢管立柱—围护结构体系进行了受力分析计算,提出了盖挖钢管立柱施工方案,分析了施工的重点难点,最后提出了有效的施工处置措施。     

Behavior of steel columns in a fire with partial damage to fire protection

An experimental study is performed on two specimens in a furnace to investigate the fire behaviour of steel columns with partial loss of fire protection. The steel columns are connected by flush end-plates at two ends and the axial load is kept constant with a load ratio of 0.55 subjected to an elevation of temperature. The specimens are protected with 20 mm thickness of fire protection. The damaged length of fire protection is 7% of the complete length of the column for specimen S-1 and 14% for S-2 at the two ends of the steel columns. The temperature of atmosphere around the specimens in the furnace is assumed to follow the ISO834 standard temperature and the temperatures and displacements are measured in the experiment. The temperature distribution along the steel column is modelled by finite element analysis and compared with the measured results. A continuum model is presented to predict the ultimate load capacity or critical temperature of the columns with fire protection damage. Analyses are carried out on the specimens and compared with the experiment. Experimental and analytical results showed that the fire resistance of steel columns with partial damage to the fire protection is reduced. The damage length of the fire protection has a great effect on the fire resistance of steel columns. The failure of the specimens mainly resulted from the buckling or yielding at the portion where the fire protection is damaged.     

露出型钢柱脚抗剪承载力的试验研究

为了确定露出型低位锚栓钢柱脚的抗剪承载力,对该类型柱脚分两种构造形式进行试验研究,一种用于研究锚栓的抗剪性能,另一种用于研究抗剪键的抗剪性能。通过试验研究和理论分析,得出柱脚抗剪P-δ滞回曲线,提出露出型低位锚栓钢柱脚在不同构造时整体抗剪承载力计算公式,并对GB 50017-2003《钢结构设计规范》中关于钢柱脚设置抗剪键方面的规定提出修改建议。     

某钢结构房屋倒塌事故分析及思考

分析了某二层钢结构房屋倒塌的过程与现状,指出结构设计缺陷是该钢结构房屋倒塌的主要原因。在此基础上,研究消除这些结构设计缺陷对结构性能的改善,并提出柱下梁无支承加劲肋时,梁翼缘最小厚度的计算方法及公式。     

基于神经网络的十字形截面方钢管混凝土组合异形柱轴压承载力研究

采用有限元法对方钢管混凝土组合异形柱轴压性能进行模拟分析,通过有限元模型的破坏形式和轴压承载力与试验结果对比,验证了有限元程序的可行性。基于有限元分析结果,训练神经网络,通过承载力的对比,二者误差较小,验证了神经网络的可行性和精确性。利用神经网络对十字形截面方钢管混凝土组合异形柱轴压承载力影响因素进行参数化分析,结果表明承载力随着钢材强度、混凝土强度、钢管高度、钢管尺寸和钢管厚度的增大而增大。     

外露式钢柱脚的设计方法

通过对外露式柱脚的受力分析,结合工程实例,对国内常用的锚栓计算方法进行比较,并对GB 50011-2010《建筑抗震设计规范》中对于柱脚锚栓的规定进行论证,可供设计人员参考。     

轴心受压方钢管-钢骨混凝土组合长柱力学性能的非线性有限元分析

基于钢管-钢骨高强度混凝土轴压组合长柱轴压试验,利用大型有限元软件ANSYS建立三维有限元数值分析模型,并对建立的模型进行非线性有限元数值模拟,分析方钢管-钢骨高强度混凝土组合长柱在轴心压力作用下的力学性能。有限元计算出来的荷载-轴向应变曲线、极限承载力和延性系数与试验结果吻合较好,证明所建立三维有限元模型和分析结果是可靠有效的;在此基础上,利用有限元模拟对若干影响组合长柱受力性能的因素进行了分析。研究表明:组合长柱截面含骨率与混凝土轴心抗压强度对方钢管-高强度混凝土组合长柱的荷载-轴向应变曲线、极限承载力和延性系数有重要影响;随着方钢管厚宽比的增大,方钢管-高强度混凝土组合长柱的屈服承载力和极限承载力均有明显的增加。     

Activated-TIG Welding of Different Steels: Influence of Various Flux and Shielding Gas

In tungsten inert gas (TIG) welding, a low depth of penetration (DOP) is achieved during single pass. To achieve the required DOP, the speed of welding should be reduced; thus productivity reduces significantly. In this work, influence of 14 different oxide-, chloride-, and fluoride-based fluxes are evaluated on DOP and width-to-penetration ratio during flux-activated TIG (ATIG) welding of low alloy steel (AISI 4340), austenitic (AISI 304 and AISI 316) and duplex (Duplex 2205) stainless steels. The effect of welding current and three different shielding gas compositions is also studied during ATIG for these workpieces. Arc and weld metal pool behaviors are captured in order to study the physical behavior of the process. Results revealed that oxide-based fluxes like SiO₂, MoO₃, MoS₂, CrO₃, and TiO₂ increases DOP significantly and in many cases through penetration (penetration reaches beyond plate thickness) is achieved. There is a noteworthy enhancement in penetration because of the addition of H₂ in shielding gas. Addition of helium also helps to increase DOP. Arc behavior reveals the constriction of arc column during activated TIG welding, and positive surface tension-induced flow in centripetal (inward) direction is observed.     

地下室上浮事故实例分析与处理

在地下水丰富地区,施工期间地下室上浮事故较为多发.以某地下室上浮事故为例,详细分析上浮事故的发生、发展及后续的增补抗拔桩、结构修复过程.对过程中综合应用的锚杆静压桩加固、托梁换柱结构修复技术进行重难点剖析,同时观测全过程建筑沉降状况,可为类似项目提供借鉴.     

“天圆地方”异形曲面清水混凝土墩台柱施工技术

以杭州萧山机场T4航站楼“天圆地方”异形曲面墩台柱为例,介绍了异形柱在施工过程中综合应用的模板选型、尺寸定位、钢筋排布、操作架设计及成形质量控制等方面的关键工艺。最终的成形质量达到了预定的目标,验证了所采用的技术与工艺流程的有效性,并为以后类似异形柱的施工提供了可供借鉴的经验。