约束高强度Q460钢梁的抗火性能

为了研究约束高强度Q460钢梁的抗火性能,在已有约束钢梁分析理论的基础上,引入残余应力,提出了约束钢梁的抗火性能分析方法,并采用普通强度约束钢梁试验数据对分析方法进行了验证。考虑高强度Q460钢材高温下力学性能参数,利用所提出的方法分析了约束高强度Q460钢梁的抗火性能,并与普通强度Q345钢梁进行了对比。对影响约束高强度Q460钢梁的抗火性能参数进行了分析,包括荷载比、残余应力、轴向约束刚度、转动约束刚度和受火方式等。研究表明:所提出的分析方法准确可靠,高强度Q460钢梁抗火性能与普通强度钢梁具有较大的区别,高强度Q460约束钢梁的抗火性能明显优于普通强度约束钢梁。荷载比、轴向约束刚度、转动约束刚度、受火方式对高强度Q460约束钢梁有较大影响。     

钢管混凝土 Y 形柱抗震性能试验研究

为了检验地铁车站地下大空间结构柱的抗震性能,对北京市某地铁车站公共设备区地下空间结构使用的单层钢管混凝土Y形柱进行低周反复荷载试验研究,主要介绍了缩比试件的设计、制作、安装和试验的方案、进行过程及结果,给出了钢管混凝土Y形柱的水平荷载-位移滞回曲线、骨架曲线、等效刚度曲线和等效阻尼比曲线统计数据,以及部分主要位置的荷载-应变曲线.试验结果及分析表明:Y形铸钢件、圆形截面钢管混凝土柱、顶板等各部分连接安全可靠,能够保证整体结构工作性能良好;试件滞回曲线较饱满,试件等效阻尼比随水平位移的增加而增大,试件耗能规律稳定,表明弹塑性变形能力和抗震性能较好.据实测应变推测,可能的薄弱部分是钢管柱底部、圆钢管与Y形铸钢件连接处和Y形铸钢节点分叉处.     

单轴扫频诱发帆板同步钢索旋转振动分析

为明确某帆板面内单轴扫频力学环境试验中同步钢索振动幅度过大和限位结构被破坏的原因,考虑集中质量和限位结构影响,采用有限段方法建立帆板同步钢索系统的动力学模型,对其在面内单轴扫频激励条件的响应进行数值模拟,结果再现了标志点的响应从面内振动发展到面外振动,再到绕两支撑点轴旋转振动的复杂振动模式,同时给出限位接触力和钢索标志点振幅,仿真结果与试验状态吻合。分析表明,持续旋转振动钢索施加在限位孔壁上的交变接触力是导致限位结构破坏的主要原因。     

钢结构中高强螺栓连接的数值模拟方法

为能够对使用众多高强螺栓群拼接的钢结构大型复杂节点进行精确的有限元数值模拟分析,并揭示螺栓拼接节点在各阶段的受力性能,提出了一种以连接件单元代替螺栓的简化模拟方法。对高强螺栓单剪连接使用实体单元建模,并考虑各种非线性影响,进行精细的有限元模拟分析。在深入研究连接的弹性、滑移、强化和屈服等各个阶段受力机理的基础上,给出了代替螺栓连接件的本构关系,并将其成功应用于简化的壳单元连接模型中。针对工程中常用的不同规格连接进行了大量算例分析,并将简化模型与精细模型计算结果进行对比,验证了所提方法在高强螺栓拉剪连接有限元模拟中的可行性,为使用数值模拟方法揭示大型复杂螺栓群连接节点的真实受力状态奠定了基础。     

均布荷载作用下保温龙骨足尺墙体的抗弯性能

为研究腹板开孔的轻钢龙骨墙体在均布荷载作用下的抗弯性能,考虑腹板高度的影响,进行3.0 m×3.0 m足尺试件试验研究．分析了不同腹板高度的墙体在均布荷载作用下的破坏模式及腹板高度对墙体抗弯性能的影响．在此基础上,采用ABAQUS建立墙体的有限元模型,与试验结果进行对比分析,验证了有限元模型的可靠性．分析结果表明:石膏板可很好地限制竖龙骨的整体屈曲,当龙骨腹板高度为150 mm时,墙体竖龙骨在支座附近发生腹板剪切屈曲,同时在跨中位置发生畸变与局部屈曲的相关屈曲破坏;当龙骨腹板高度为100 mm时,墙体竖龙骨在跨中位置发生畸变与局部屈曲的相关屈曲破坏;当不考虑窗洞口影响时,腹板高度为100 mm的保温龙骨外围护墙体可满足我国全部地区建筑高度不超过50 m的城市建筑外围护墙体的抗风要求．     

基于磁极偏移圆筒永磁直线电机齿槽力的削弱

为了削弱圆筒型永磁直线电机的齿槽力,在简要介绍圆筒型永磁直线电机齿槽力产生原理的基础上,基于Ansoft软件对圆筒型永磁直线电机的齿槽力进行了分析.以单个磁极和初级齿相互作用产生的齿槽力为基础,运用叠加原理得到整个电机的齿槽力解析表达式,进而提出采用磁极分组偏移来削弱电机齿槽力的方法,并给出了磁极偏移距离的表达式.通过有限元仿真验证了该方法的有效性,同时对磁极偏移后电机的反电势进行了分析,发现该方法对电机反电势的影响很小,所得结论可为直线电机的设计提供一定参考.     

Comparison of hydration properties between cement-GGBS-fly ash blended binder and cement-GGBS-steel slag blended binder

The hydration properties of cement-GGBS-fly ash blended binder and cement-GGBS-steel slag blended binder were compared. The experimental results show that the hydration rate of cement-GGBS- steel slag blended binder is higher than that of cement-GGBS-fly ash blended binder within 28 days, but lower than the latter after 28 days. The hydration of cement-GGBS-steel slag blended binder tends to produce more Ca（OH）2 than the hydration of cement-GGBS-fly ash blended binder, especially at late ages. Cement-GGBS- steel slag mortar exhibits higher strength than cement-GGBS-fly ash mortar within 28 days, but at late ages, it exhibits similar compressive strength with eement-GGBS-fly ash mortar and even slightly lower bending strength than cement-GGBS-fly ash mortar. Cement-GGBS-steel slag paste has finer early pore structure but coarser late pore structure than cement-GGBS-fly ash paste. Cement-GGBS-steel slag paste can get satisfied late pore structure and cement-GGBS-steel slag mortar can get satisfied late strength as compared with pure cement paste and pure cement mortar, respectively.     

钢管混凝土柱与型钢梁装配式节点抗震试验

为了研究一种新型钢管混凝土柱与型钢梁装配式节点的抗震性能,对不同参数的节点进行低周往复循环加载试验.节点均经历弹性、塑性和极限破坏三个阶段,且为环板与钢梁翼缘的连接处破坏.对比分析表明：节点的轴压比越大,承载力越低;环板越宽,承载力越高;方形环板比圆形环板承载力更高;垫板对节点试件的承载力有提高作用.钢管混凝土柱与型钢梁装配式节点设计合理、传力明确、承载力高、构造简单、施工方便,是一种值得推广的组合装配式节点形式.     

TRIP steel retained austenite transformation under cyclic V-bending deformation

To investigate the transformation behavior of TRIP steel retained austenite under cyclic load, cyclic V-bending deformation of low carbon Si-Mn TRIP600 was studied by experiment and finite element in this paper. The results showed that, under cyclic V-bending deformation, retained austenite in TRIP steel transformed into martensite gradually with the increasing of bending times, and for the symmetrical characteristic, upper surface and lower surface presented the same transformation tendency. From the first to the fourth V-bending deformatiort, retained austenite volume fraction decreased nearly linearly and then attained saturation step by step. Compressive stress state was helpful for martensite transformation than tension stress state with V-bending deformation, and strain magnitude was the determining factor for retaining anstenite martensitic transformation. With the increasing of bending times effective stress increased and the relationship between maximum effective stress and bending times was nearly linear. Effective stress and effective strain distribution were non-uniform, the maximum effective stress and effective strain were present in the center of the samples. The relationships between retained austenite and V-bending times, and retained austenite with effective strain were set up as Eqs.（1）-（5）. The relationship was typical quadric function, decreased linearly for the initial deformation and attained saturation finally.     

Synthesis of calcium silicate hydrate based on steel slag with various alkalinities

This study aimed to improve the hydraulic potential properties of the slag. Therefore, a method of dynamic hydrothermal synthesis was applied to synthesize calcium silicate hydrate. The phases and nanostructures were characterized by XRD, FTIR, TEM, and BET nitrogen adsorption. The infl uence of alkalinity of steel slag on its structures and properties was discussed. The experimental results show that, the main product is amorphous calcium silicate hydrate gel with fl occulent or fi brous pattern with a BET specifi c surface area up to 77 m2/g and pore volume of 0.34 mL/g. Compared with low alkalinity steel slag, calcium silicate hydrate synthesized from higher alkalinity steel slag is prone to transform to tobermorite structure.