Earthquake-resistant behavior of short-limbed wall

The seismic resistance properties of the structures of short-limbed walls (SLW) were explored by horizontal cyclic loading experiments on 6 SLW specimens including 3 flanged and 3 non-flanged. The ratios of the depth to the width of the 3 specimens in each group were 5, 6.5 and 8, respectively. For non-flanged SLW structures with a small depth-to-width ratio, longitudinal bars in the limb yield first;and for those with a large depth-to-width ratio, stirrups in a linking beam yield first. For a structure with different depth-to-width ratio varying from 5 to 8, the failure mode is different. Correspondingly, different calculation model should be used in the design and engineering of the structure. For flanged SLW structures with whatever depth-to-width ratio, longitudinal bars in a flange or limb yield first. The SLW structures with a depth-to-width ratio of 6.5 exhibit the best comprehensive seismic resistant property and flanged walls have a better ductility than non-flanged ones.

Seismic retrofi tting of RC columns with RC jackets and wing walls with different structural details

An original reinforced concrete(RC) column and four strengthened specimens, two with RC jackets and two with wing walls, were tested in this study. The original column specimen was designed to comply with older(pre-1999) design standards so that the usual detailing defi ciencies in existing school buildings in Taiwan could be simulated. Two different structural details were chosen to fabricate the full-scale specimens for each retrofi tting technique. The study confi rmed that either RC jacketing or the installation of wing walls with two different structural details can effectively improve the stiffness and strength of an existing column. RC jacketing shows a better improvement in energy dissipation and ductility when compared to the columns with wing walls installed. This is because the two RC jacketed columns experienced a fl exural failure, while a shear failure was found in the two columns with the wing walls installed, and thus led to a drastic decrease of the maximum lateral strengths and ductility. Since many factors may affect the installation of a post-installed anchor, it is better to use standard hooks to replace post-installed anchors in some specifi c points when using RC jacketing or installing wing walls.

Nonlinear Finite Element Analysis of Mechanical Performance of Reinforced Concrete Short-Limb Shear Wall

On the basis of test, nonlinear finite element analysis of reinforcedconcrete (R. C) short-limb shear walls under monotonic horizontal load are carried out by ANSYSprogram in order to understand the evolution of cracking, deformation and failure course of thespecimens. At the same time, the results of numerical calculation are compared with the results oftest. The results indicate that, under monotonic horizontal load the failures of the specimens withflange wall and without flange wall all occur at the intersections of lintel bottom and limb ofwall, the failures also occur at the bottom of limb; the load-displacement curve of wall withoutflange is steeper than that of wall with flange, and the ductility is worse than that of wall withflange; the results, such as cracking, deformation, yield load and so on of finite element analysisagree well with the results of test. These results provide theoretical basis of study andapplication of R. C short-limb shear wall.

Effect of trapezoidal collars as a scour countermeasure around wing-wall abutments

Local scour around bridge abutments is a widespread problem that can result in structural failure. Collars can be used as a countermeasure to reduce the scour depth. In this study, the temporal scour development around a wing-wall abutment was investigated with and without collars. The tests were carried out under clear-water conditions for different abutment lengths, with collars of different sizes placed at the bed level. When no collar was used in the experiments, 70% of the maximum scour depth occurred in less than 2 h. However, when a collar with a width greater than the length of the abutment was used, no scour was observed for up to 200 min from the beginning of the experiments. The results show that an increase in the collar width not only led to a lag time for the onset of scouring but also reduced the maximum scour depth. Moreover, an increased collar width led to a better performance in mitigating scouring around smaller abutments. Generally, the scour depth decreased by 9%-37% with different collar widths.

一种高硬度复杂薄壁翼片的机械加工工艺设计

一种高硬度复杂薄壁翼片目前没有高速铣削的加工手段可利用,需要普通铣削结合真空炉处理的方式来满足产品技术要求,加工难度大,生产进度紧。通过工艺攻关、工艺优化形成了翼片的机械加工工艺方案,采用普通铣削后进行真空炉淬火的方式保证翼片角度、厚度、孔径和力学性能要求,最后用电火花切割的方式将工件与工艺台分离保证翼轴孔距和外形尺寸。结合真空炉处理和电火花切割的特点,及时处理了加工过程中出现的热处理变形、切割外形导致孔距超差等技术问题,最终保证首批次合格产品按进度交付。所涉及到的翼片工艺方案、工艺台、定位基准选择、控制热处理变形的工装、电火花切割工装等内容属于西安现代控制技术研究所首次应用,具有创新性,对于弹体结构件中技术要求较高的翼片及同类结构的零件有一定的参考价值。

湿工况下带翼翅片管传热传质特性的数值研究

采用壁面反应原理建立冷凝传热模型,模拟研究平直翅片管、矩形翼翅片管以及弓形翼翅片管的通道内湿空气流动及传热传质特性。结果表明:当湿空气入口温度为328 K,水蒸气质量分数为11.2%时,矩形翼翅片管和弓形翼翅片管的传热因子相比于平直翅片管分别提高了24.9%—35.7%、26.7%—36.4%,传质因子分别提高了24.1%—35.4%、25.9%—38.3%,但矩形翼翅片管和弓形翼翅片管通道内工质的流动阻力系数分别增加了19.4%—25.3%、16.8%—22.9%,说明了矩形翼和弓形翼均可提高翅片管的传热传质特性,但也造成了阻力损失的增加。通过对综合传热性能评价因子的分析,矩形翼翅片管和弓形翼翅片管的综合传热性能评价因子值均>1,其综合传热性能均优于平直翅片管,且弓形翼翅片管综合传热性能最优。

350 MW超临界机组高温再热蒸汽管道下沉原因分析及治理

某350 MW超临界机组运行一段时间后,高温再热蒸汽管道锅炉侧支管存在大范围下沉现象,连续布置的恒力吊架指针大部分超出下极限位置。结合现场检查、测量,对管道进行多工况应力计算分析研究。结果表明:该机组循环流化床锅炉翼形墙结构高温再热器管屏变形,且变形量不均引起出口集箱端口处产生异常 X向角位移以及Z 向线位移是造成管道下沉的主要原因,恒力吊架荷载偏差度和恒定度超标是造成其下沉的次要原因。在不更换变形受热面管屏的前提下,充分利用管道柔性制定治理方案,改善管道及支吊架工作状态,优化管系应力水平。同时,对后期彻底解决管屏变形及管道下沉问题提出解决思路,可为同类机组管道的设计、维护和位移异常故障解决提供参考。

免翼墙路基桥梁过渡段护栏设计在高速公路中的应用

随着我国经济的不断发展,高速公路的建设里程不断增加。同时,车辆组成及车流量特征的巨大的变化,导致交通量及载重量不断增加,群众出行也对公路桥梁过渡段的防护提出了更多的要求。因此,为了避免车辆在桥梁过渡段处发生安全事故,提升公路桥梁过渡段护栏的防护能力迫在眉睫。文章针对免翼墙路基桥梁过渡段护栏设计在高速公路中的应用进行研究,根据路基桥梁过渡段护栏现状和免翼墙路基桥梁过渡段护栏设计原则,提出其结构设计及材料和安装要求,以供参考。

鹤大高速公路护栏改造工程新材料及新工艺应用研究

G11鹤大高速公路运行近20年,现状护栏腐蚀严重。为保证高速公路运营管理的顺畅及用路人的安全,文章着眼该高速公路波形梁钢护栏改造升级,采用更加环保的高性能熔融结合环氧粉末进行防腐涂装。该防腐涂装是一种绿色、成熟、低能耗的新型环保涂装技术,涂装后的钢构件耐腐蚀性能优异,更具有超长耐久性、高性价比和轻维护等特性。

Stall Flutter Analysis of High-Aspect-Ratio Composite Wing

The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. Firstly, the high-aspect-ratio wing is modeled as a composite thin-walled closed section Euler beam whose displacement and rotation both could be of finite value, and the nonlinear dynamic equations is build up on it with all the effects of geometric nonlinearity, aerodynamic nonlinearity and anisotropy of material being considered. Then vibration equations are deduced through perturbing the dynamic equations at wing＇s equilibrium position, and coupled with unsteady stall aerodynamic model and ONERA model, to obtain the nonlinear stall flutter analysis equations of wing. Finally, the flutter stabilities with various wind speeds are determined by the harmonic balance method. With several exampies, the validity of the stall flutter model is proved, and the significant effects of geometric nonlinearity on the stall flutter various characters as wall as the effects of ply angle on the stall flutter speed and frequency also are discussed.

基于剪切变形宽翼薄壁工字形梁剪滞效应的分析

分析了宽翼薄壁工字形梁竖向弯曲时的翼缘和腹板剪力流分布规律,利用剪切变形来定义剪滞翘曲位移函数,采用基于最小势能原理的能量变分法,建立了宽翼薄壁工字形梁剪滞效应分析的剪力滞控制微分方程和边界条件。以剪力滞广义位移、竖向挠度、竖直平面内转角、剪力、弯矩及剪力滞广义力矩作为6个初参数,给出了任意集中荷载作用下微分方程的初参数解。对简支工字形截面梁模型进行计算,应力和挠度计算结果与有限元较吻合,证明该方法有效。

考虑填充墙刚度的RC框架结构抗震设计方法研究

针对填充墙框架结构在地震作用下不同阶段填充墙提供的刚度不同,收集了国内外相关计算公式并建立回归模型进行公式拟合,得到了填充墙不同阶段的抗侧刚度计算方法。通过增设翼墙来解决填充墙框架结构楼层内各榀框架刚度不平衡的情况,设计了4个数值模型(1个原型结构与3个分别基于弹性阶段、屈服阶段、承载力峰值阶段实现刚度平衡设计的翼墙加固结构),通过IDA分析对4个模型进行抗震性能评估。结果表明,考虑填充墙刚度进行刚度平衡设计后的3个模型较原型结构相比:各层最大层间位移角减小,离散性降低,结构抗地震倒塌能力提高。对比分析4个模型结构可得,基于填充墙屈服阶段刚度平衡进行翼墙刚度需求设计的效果最佳。

一种用于吸气式电推进的新型吸气装置研究

为提升吸气式电推进吸气装置的气体收集率,本文设计一种新结构的吸气装置,即附有近壁阻翼结构的抛物型吸气管。以单元粒子/直接蒙特卡罗碰撞模型(PIC/DSMC)对传统抛物型和新型结构的吸气管进行流场参数分布的数值计算。计算结果表明,近壁阻翼对于壁面附近返流有较强的阻碍作用,可令返流粒子数量减少,气体收集率可提高2%~10%不等;近壁阻翼的位置和长度对气体收集率有较大影响,主要表现在阻翼对来流阻挡作用和对返流阻挡作用两者的占比程度,在本文工况中(轨道高度为180km,适应系数σ=0.3),气体收集率的最优值为47.3%。

小型折叠弹翼加工工艺研究

针对某型折叠弹翼机构中翼根和外翼平面度要求高,需对转轴深孔进行加工,以及薄壁结构容易导致变形等加工难题,提出了先粗铣,再钻深孔,最后以孔为基准精铣外形的加工策略,重点研究了深孔加工方法和翼面立式装夹精铣方法,并研究了其工艺参数。结果表明,所设计的工艺具有加工精度高、效率高且质量稳定的优点,为今后此类产品的加工提供了成功的经验。

Nonlinear finite element analysis of short-limbed wall

Combined with the actual project,this paper carries out a nonlinear finite element analysis on 2 groups,6 short-limbed shear walls,through the finite element calculation software ANSYS.The stress-strain relation of the models,and the effects of the type of sections and the axial compression ratios on the models can be obtained,providing a reference for future design.

基于通风环境的高校教学楼翼墙改造研究——以徐州地区为例

新冠疫情的出现使人们意识到自然通风的必要性。高校教学楼内部聚集着大量的人员,室内通风环境的优劣对于学生和教职员工的健康和学习至关重要。利用翼墙的设计和Phoenics软件的应用,对中国矿业大学徐海学院教一南楼进行自然通风优化设计,从而改善其通风状况。

三角翼过失速非定常洞壁干扰修正

利用定常壁压洞壁干扰修正法算出的影响函数和洞壁最佳点测出的非定常壁压数值，进行低速风洞三角翼过失速非定常洞壁干扰修正。研究表明，非定常洞壁干扰修正有类似非定常空气动力的所谓滞迟环现象。非定常洞壁干扰修正量随频率增大开始增大，以后随频率增大而减小，呈现所谓“风洞谐振”趋势。在同样模型展长与风洞宽度之比条件下。

翼墙式隧道洞门可靠性分析

根据结构可靠性理论 ,在考虑了隧道洞门处的地层容重、地层计算摩擦角正切值、基底摩擦系数、基底控制压应力和混泥土容重等因素的不确定性前提下 ,运用一次二阶矩法对隧道洞门结构进行可靠性分析。由计算结果得 :计算模型的选取与可靠度指标有关 。

三种跨声速洞壁干扰修正方法及其在小展弦比飞翼标模试验中的应用

在FL-24风洞进行了带壁压信息测量的小展弦比飞翼标模测力试验,并在FL-26风洞进行了洞壁干扰验证试验。本文利用小扰动位流壁压信息法、全速势位流方法、基于RANS的壁压信息法三种方法开展飞翼标模的洞壁干扰修正研究,并与试验结果进行了比较。结果表明,飞翼标模洞壁干扰呈现与翼身尾常规布局不同的规律,三种方法在飞翼标模洞壁干扰修正中有各自的适用性。

小展弦比飞翼标模FL-2风洞跨声速开孔壁干扰特性修正研究

为了满足现代风洞试验精细化要求,提高风洞试验数据精准度,开展跨声速开孔壁洞壁干扰修正方法研究。本文利用实测壁压信息构造开孔壁边界条件,通过求解N-S方程,模拟试验模型在风洞中的绕流场,建立基于壁压信息的跨声速洞壁干扰非线性修正方法。不同于线性修正方法,本方法可用于各种复杂外形飞行器的亚、跨声速开孔壁洞壁干扰修正,结合小展弦比飞翼标模风洞试验数据,对其在FL-2风洞试验数据开展洞壁干扰特性研究。洞壁干扰修正结果表明,洞壁干扰量随马赫数变化呈增长趋势,Ma=1.0左右达最大,经过修正的FL-2风洞的跨声速试验结果,与FL-26风洞近似无干扰试验结果吻合良好。