Nonlinear Study on the Mechanical Performance of Built-Up Cold-Formed Steel Concrete-Filled Columns under Compression

Given their numerous functional and architectural benefits,such as improved bearing capacity and increased resistance to elastic instability modes,cold-formed steel(CFS)built-up sections have become increasingly developed and used in recent years,particularly in the construction industry.This paper presents an analytical and numerical study of assembled CFS two single channel-shaped columns with different slenderness and configurations(backto-back,face-to-face,and box).These columns were joined by double-row rivets for the back-to-back and box configurations,whereas they were welded together for the face-to-face design.The built-up columns were filled with ordinary concrete of good strength.Finite element models were applied,using ABAQUS software,to assess mechanical performance and study the influence of assembly techniques on the behavior of cold-formed columns under axial compression.Analytical approaches based on Eurocode 3 and Eurocode 4 recommendations for un-filled and concrete-filled columns respectively were followed for the numerical analysis,and concrete confinement effects were also considered per American Concrete Institute(ACI)standards for face-to-face and box configurations.The obtained results indicated a good correlation between the numerical results and the proposed analytical methodology which did not exceed 8%.The failure modes showed that the columns failed due to instabilities such as local and global buckling.

Numerical Analysis of Cold-Formed Thin-Walled Steel Short Columns with Pitting Corrosion during Bridge Construction

Pitting corrosion is harmful during bridge construction,which will lead to uneven roughness of steel surfaces and reduce the thickness of steel.Hence,the effect of pitting corrosion on the mechanical properties of cold-formed thin-walled steel stub columns is studied,and the empirical formulas are established through regression fitting to predict the ultimate load of web and flange under pitting corrosion.In detail,the failure modes and load-displacement curves of specimens with different locations,area ratios,and depths are obtained through a large number of non-linear finite element analysis.As for the specimens with pitting corrosion on the web,all the specimens are subject to local buckling failure,and the failure mode will not change with pitting corrosion,but the failure location will change with pitting corrosion location;the size,location,and area ratio of pitting corrosion have little influence on the ultimate load of cold-formed thin-walled steel short columns,but the loss rate of pitting corrosion section area has a greater impact on the ultimate bearing capacity.As for the specimen with flange pitting corrosion,the location and area ratio of pitting corrosion have less influence on the ultimate load of cold-formed thin-walled steel short columns,and the section area loss rate has greater influence on the ultimate bearing capacity;the impact of web pitting corrosion on the ultimate load is greater than that of flange pitting corrosion under the same condition of pitting corrosion section area.The prediction formulas of limit load which are suitable for pitting corrosion of web and flange are established,which can provide a reference for performance evaluation of corroded cold-formed thin-walled steel.

Some Advances in the Application of Weathering and Cold-Formed Steel in Transmission Tower

Application of weathering and cold-formed steel in transmission lines can reduce steel consumption and environmental pollution. Some advances in the studies on the weathering and cold-formed steel in transmission tower are introduced. Firstly, corrosion-resistant tests of weathering steel samples under different simulating technical atmospheres were carried out separately for 240 hours. It shows that the corrosion degree of joint samples is higher than that of single chip samples, and the corrosion-resistant performance of weathering steel is superior to common carbon steel. The corrosion-resistance of weathering steel meets with the requirement of transmission tower. Secondly, experiments and finite element analysis for cold-formed angles and a 220kV prototype tower were completed, and the stability coeffi-cient fitting curves as well as the modification formulas of slenderness ratio for cold-formed members were determined. According to the structural characteristics of transmission towers, four sections of cold-formed angles with different sections and slenderness ratios were selected in this study. The finite element model well predicted the buckling behav-iour of the cold-formed members. Ultimate loads calculating by the fitting curve were well agreed to the experimental values, especially for the members with small slenderness ratios. Weight of the cold-formed steel tower can be reduced by more than 5 percent after considering the strength enhancement. Cost of the weathering and cold-formed steel transmission tower is nearly equivalent to that of hot-rolled steel tower with hot galvanizing.

Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

In this study, the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at normal room temperature was investigated. The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen. Based on the experimental results, an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed. The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures. It is shown that the predictions obtained from the proposed model agree well with the test results. Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.

Mechanical Properties of Two Kinds of New Cold-Formed Flange-Closed Welding Section Members

The hollow flange beam(HFB) is a unique cold-formed steel section developed in Australia for use as a flexural member.It′s a particular cross section with two torsion rigid closed triangular flanges and a comparatively flexible web,and it is a type of high efficient cross section.This paper presents two kinds of new cold-formed flange-closed welding sections named HF1 and HF2 according to different section component and parameters of HFB.Nonlinear finite element method has been adopted to investigate the mechanical properties such as buckling mode,deformation process,rigidity,ductility and correlation curve of two kinds of new section members which being subjected to axial compression,flexure,combined compression and bending.Systematical comparisons of the consumed steel quantities of per unit load carrying capacity between new section members and the same section dimensions of cold-formed C-section members have been carried out.Some conclusions can be drawn from above work that the new sections have some superior properties including higher load carrying capacity and section modulus,sufficient section stiffness,and difficult occurrence for the sub element local buckling.The new sections are suitable for bearing flexure,compression,combined compression and bending.The new sections′ consumed steel quantities of per unit load carrying capacity are almost half as those of the same dimension C-section members′.The experimental investigation is carried out further on the new cold-formed flange-closed welding section members and can be used in the practical engineering.

工业厂房屋面自承重式冷弯成型天沟的研究与应用

天沟是工业厂房屋面排水系统中重要的组成部分,具有承上启下的作用。当前工程应用中的构造较为烦琐,对制造和安装的要求较高,耐久性也难以保证。分析天沟的各种不同承载工况与相应的受力模型,针对性优化其构造措施,将为天沟标准化生产创造有利条件。经研究和实践应用对比分析,优化后的自承重式一体成型冷弯薄壁型钢天沟更加节能环保,施工制造、施工安装便捷,工程适应性强,具有显著的经济效益,应用前景良好。

UNIBODY技术在产品设计中的应用

现代科技日新月异,越来越多的工业产品被生产出来,各种各样的产品加工工艺也层出不穷。产品设计师应如何把自己的设计思维融入到现代先进制造工程之中呢?当前又有什么样的先进制造工艺可以被我们使用呢?本论文带着以上的疑问去探寻当前产品设计界十分关注的产品制造工艺——Unibody技术。认真去理解这种技术的现状、特征、局限性、前景以及这种技术会给产品设计界所带来的变动和新活力等。

基于高性能计算的云原生超大规模压铸模拟技术

针对新能源汽车一体化超大型压铸的发展和未来巨大需求,亟需实现超大型压铸多物理场建模与超大规模高效高精度仿真计算,本研究基于完全自主研发的自适应结构化网格剖分算法,不可压缩格子玻尔兹曼热流体仿真求解器算法,以及实验测量+一维反算的铸件-铸型界面换热系数模型,研发了高性能云原生超大规模压铸模拟软件。计算案例结果表明:自适应结构化网格在复杂几何建模场景更为优异,对于一体式车身等超大型压铸件,其计算规模和并行效率均突破了传统铸造仿真软件的计算能力瓶颈,总体计算网格规模为1.22亿,计算CPU核心数为96核时,总计算时间仅为13 h 43 min。

非常规油气内涵辨析、源-储组合类型及中国非常规油气发展潜力

通过辨析非常规油气术语内涵,将非常规油气的源-储组合关系划分为源-储紧邻型、源-储一体型和源-储分离型3种类型。源-储紧邻型资源主要包括致密油、致密气,其形成条件及特征为:1紧邻优质烃源岩,以源-储压差为动力的近源高效聚集;2具有一定孔隙度的大面积致密储层,以微—纳米级无机成因孔隙为主;3分布于凹陷及斜坡区,含油气面积及资源规模大,丰度低,局部发育甜点;4构造作用较弱。源-储一体型资源主要包括煤层气、页岩气、页岩油、油页岩,其形成条件及特征为:1有机质丰度高,有机质类型及热演化程度形成不同类型的资源;2储集空间以纳米级有机质孔、粒间孔和微裂隙为主,富有机质集中段连续分布;3烃类主要以游离、吸附方式赋存,不同资源类型差异大;4具有自封闭性,保存条件受构造、温度、压力等控制,凹陷及斜坡富集;5通过体积压裂'人造渗透率'来提高单井产量。源-储分离型资源较特殊,主要包括:1经过改造的常规资源,如油砂、重油等;2特殊的温、压条件下形成的非稳态资源,以天然气水合物为代表。中国3类源-储组合资源的发展前景与现实性有差异:1源-储紧邻型资源最现实,未来5年将快速发展;2源-储一体型资源需要持续探索和技术攻关,未来10年有望较快发展;3源-储分离型资源以天然气水合物最具发展潜力,正在开展技术试验。

一体式覆膜支架的解剖固定方式在腹主动脉瘤血管腔内治疗中的应用

目的探讨应用一体式覆膜支架的解剖固定方式治疗腹主动脉瘤的临床疗效。方法2007年7月-2013年3月应用Powerlink一体式覆膜支架治疗腹主动脉瘤患者7例，术中均置入一体式覆膜支架，并采用骑跨状将其固定于腹主动脉分叉处，称为“解剖固定”方式。分别于出院前，出院后1、6个月和1年，以及每年定期行增强CT检查支架在位情况。结果7例腹主动脉瘤患者手术均获成功。其中l例术中加用左侧髂动脉延长支架，术中造影检查显示支架近端发生I型内漏，加用近端Cuff后内漏消失；2例患者术中分别加用双侧髂动脉延长支架和右侧髂动脉延长支架；1例患者在术中造影检查发现左侧髂腿分支末端扩张不全而加用远端裸支架；3例患者植入单独的一体式覆膜支架即能完全修复病变。出院前行增强CT检查见支架的位置和形态均正常。所有患者术后均获随访，随访时间3～68个月，中位随访时间为11个月，随访期间定期行增强CT检查见支架的位置和形态均正常，无1例患者发生内漏和支架移位，且无动脉瘤破裂。结论采用一体式覆膜支架的解剖固定方式治疗腹主动脉瘤是安全、有效的。

一体式分叉型覆膜支架在介入治疗孤立性髂动脉瘤中的应用

目的:探讨一体式分叉型覆膜支架应用于介入治疗孤立性髂动脉瘤(IIAAs)的安全及有效性。方法:回顾性分析本中心自2011年8月至2016年7月,共7例男性患者,年龄49~82岁,平均年龄(69±10.5)岁,因IIAAs接受一体式分叉型覆膜支架介入治疗。其中单侧病变3例;双侧病变4例,4例合并髂内动脉瘤。6例患者使用Microport Aegis-B一体式分叉型覆膜支架,1例使用Powerlink一体式分叉型覆膜支架,远端共使用9枚髂动脉延长支架。1例患者行髂内动脉预栓塞以避免II型内漏。术后分别于1、6、12个月及以后每年一次行临床及影像随访。结果:7例患者均成功置入一体式覆膜支架,技术成功率为100%。一体式支架主体近端直径为24~26 mm,长度为80~90 mm。6例患者单侧髂内动脉开口覆盖,1例患者双侧髂内动脉开口覆盖,无盆腔及臀肌缺血发生,围术期无严重并发症发生。平均随访时间(32.5±19)个月(12~70个月)。患者随访期内无支架移位,无支架相关死亡等严重并发症。1例随访内发现轻度II型内漏。结论:一体式分叉型覆膜支架治疗IIAAs安全有效,近中期疗效满意,特别是对于近端锚定区不足或双侧受累的患者有其独到特殊的应用优势。

分叉型一体式覆膜支架腔内治疗肾下型腹主动脉瘤的疗效

目的:探讨应用分叉型一体式覆膜支架腔内治疗腹主动脉瘤和髂动脉瘤的疗效。方法:回顾分析采用分叉型一体式覆膜支架治疗的20例肾下型腹主动脉瘤和髂动脉瘤患者的临床资料。结果:20例患者植入分叉型一体式覆膜支架的手术成功率达100%,无围手术期死亡患者,且所有患者均未出现各类缺血性并发症。8例患者术后存在少量内漏(6例Ⅰ型内漏,2例Ⅲ型内漏),1周后内漏消失;1例患者术后发生急性肝肾功能不全,经内科治疗1周后恢复;2例患者术后出现腹股沟切口淋巴瘘,经换药愈合。平均随访15个月,所有患者未出现新的内漏和支架移位。1例患者术后1年在左侧分支支架内形成血栓,左侧髂动脉局部无血流,经导管接触溶栓治疗1 d后实现血管再通。结论:应用分叉型一体式覆膜支架腔内治疗腹主动脉瘤安全有效。

一体式分支型覆膜支架治疗腹主动脉-髂动脉分叉部病变的疗效分析

目的探讨一体式分支型支架在腹主动脉-髂动脉分叉部病变中的应用效果。方法回顾性收集2016年8月至2019年1月在首都医科大学附属北京世纪坛医院血管外科接受一体式分支型覆膜支架治疗的18例腹主-髂分叉部病变患者资料,分析其技术成功率和术后疗效。结果 17例患者成功植入一体式分支型覆膜支架系统,技术成功率94.4%。病例均成功使用预置血管缝合器成功封堵穿刺点,无穿刺点出血、假性动脉瘤、闭塞等并发症,平均住院时间(5.0±0.6)d。患者平均随访(13.0±3.0)个月,无支架相关死亡,无动脉瘤及支架移植物破裂,无支架移位。所有患者支架内血流通畅,无髂支闭塞病例,通畅率为100%。术后3个月发现Ⅱ型内漏1例,术后6个月复查时消失,未发现其他类型内漏。结论一体式分支型覆膜支架治疗腹主动脉-髂动脉分叉部病变安全有效,近中期疗效满意,但长期效果还有待进一步研究。

一体式分支支架在主髂动脉病变治疗中的应用

目的探讨一体式分支支架在主髂动脉病变治疗中的应用效果。方法选取2009年3月至2015年8月于首都医科大学附属北京安贞医院接受一体式分支支架治疗的61例主髂动脉病变患者,分析其技术成功率、术后并发症发生率及术后1年、2年、3年存活率。结果 60例成功植入一体式分叉型覆膜支架,1例由于入路血管狭窄术中输送器无法送入腹主动脉上段,术中选择将Medtronic髂分支支架倒装进行释放,技术成功率为98.4%(60/61)。平均手术时间为(156±54)min,平均随访时间为(32.5±19.0)个月。术后1年存活率为98.4%(60/61),2年存活率为94.1%(48/51),3年存活率为82.4%(28/34)。术后随访中,61例患者均无支架移位,无支架相关死亡,术后并发症包括1例Ⅰ型内漏,1例支架感染,1例于术后5年支架以远髂总动脉动脉瘤形成。结论熟练掌握一体式分支支架的特点,对于解剖学受限的主髂动脉病变可以有效地节省手术时间,近、中期疗效满意,远期疗效尚需进一步随访。

一体式覆膜支架腔内治疗主、髂动脉附壁血栓1例报告

本文报道2013年1月使用一体式带膜支架成功治疗1例腹主动脉溃疡伴左侧髂动脉狭窄并附壁血栓。术后第5天复查,覆膜支架通畅,位置形态良好,附壁血栓隔绝完全。

一体化分叉型支架在肾下型腹主动脉瘤腔内治疗中的应用

目的探讨一体化支架在肾下型腹主动脉瘤治疗中的应用。方法回顾分析2010年3月至2013年2月采用一体化支架腔内修复术治疗肾下型腹主动脉瘤15例，对其临床资料进行分析总结。结果所有病例均腔内修复成功，术后随访3—36个月复查CTA，瘤体均被完全隔绝，支架位置良好，无移位、扭曲及内漏现象。结论术前准确评估、测量后，一体化支架治疗肾下性腹主动脉瘤效果良好，安全性高，操作简单并发症少。

一体式支架在腹主动脉病变腔内治疗中的应用

腹主动脉病变的治疗以往以开放手术为主,随着腔内器械的发展以及技术的进步,逐步转变为以腔内治疗为主。在支架选择上有分体式支架和一体式支架,一体式支架在腹主动脉病变的腔内治疗中有其自身的特点,本文对一体式支架在腹主动脉病变中的应用进行文献总结。

一体式单分支支架在胸主动脉疾病中的临床应用效果分析

目的评估Castor一体式单分支支架在胸主动脉疾病中的临床应用效果。方法回顾性分析佛山市第一人民医院2018年10月至2020年7月应用Castor一体式单分支支架治疗59例需重建左锁骨下动脉(left subclavian artery,LSA)的胸主动脉疾病患者的临床资料,其中35例为主动脉夹层,13例为近弓部主动脉瘤,11例为胸主动脉穿透性溃疡。结果患者均成功完成单分支支架植入,手术技术成功率100%;手术平均时间为(156±45)min。围术期并发症发生率为6.8%(4/59)。1例患者术中支架释放后存在LSA狭窄,1例分支支架部分遮挡左椎动脉,1例因瘤体较大出现主体支架近端移位,1例术后出现Ⅰa型内漏。术后1年LSA分支支架通畅率为98.3%(58/59),无截瘫等严重并发症和死亡发生。结论Castor一体式单分支支架治疗需重建LSA血流的胸主动脉疾病的短期疗效满意。

Castor一体式分支支架在胸主动脉瘤治疗中的应用效果

目的探讨Castor一体式分支支架在胸主动脉瘤治疗中的应用效果。方法收集佛山市第一人民医院2018年10月至2020年7月应用Castor一体式分支支架治疗的13例需重建左锁骨下动脉(LSA)的胸主动脉瘤患者的临床资料,其中3例患者行颈-颈搭桥联合Castor支架植入,10例患者单纯行Castor支架植入。术后第12个月,全部患者均于门诊复查计算机断层扫描血管造影(CTA)。结果13例重建LSA的胸主动脉瘤患者均成功完成Castor单分支支架植入手术,手术技术成功率100%;手术平均时间为(174±56)min;术中1例患者LSA分支支架释放后存在狭窄,给予球囊扩张后狭窄解除;术中有1例因LSA分支支架部分遮挡左椎动脉,遂植入支架开通椎动脉;术中有1例因瘤体较大出现主体支架近端缩入瘤体致Ia型内漏,遂行无名动脉开窗术,术后无名动脉血流通畅,内漏消失;术后无左上肢缺血、内漏、脑梗死、死亡病例发生。随访至12个月时,LSA分支支架的通畅率为100%,无截瘫、新发内漏、死亡病例。结论Castor一体式分支支架应用于重建LSA的胸主动脉瘤患者治疗中,短期疗效满意,安全可靠,并发症少,值得临床推广。

一体式分叉型覆膜支架在腹主动脉病变腔内修复中的应用

目的探讨一体式分叉型覆膜支架腔内修复腹主动脉病变的安全性、有效性及适合人群。方法回顾性分析2016年8月至2018年10月采用一体式分叉型覆膜支架行腔内修复术治疗的11例腹主动脉病变患者临床资料,其中腹主动脉夹层伴髂总动脉夹层4例(36.4%),腹主动脉瘤2例(18.2%),腹主动脉壁内血肿伴髂总动脉夹层、腹主动脉溃疡伴髂总动脉闭塞、髂总动脉夹层、腹主动脉瘤伴髂总动脉瘤、髂总动脉瘤各1例。评估手术治疗效果,术后支架变形、移位及内漏,支架内血流通畅情况,观察术后并发症。结果11例患者腔内修复术均获成功,围手术期未出现严重并发症。术后3、6个月无支架变形或移位发生,支架内血流通畅率均为100%,无一例死亡。术后3个月发现Ⅰ型内漏1例,术后6个月复查时消失。术后1个月1例出现心力衰竭,入院治疗后好转。结论一体式分叉型覆膜支架治疗腹主动脉病变安全有效,对入路血管损伤小、支架无移位,适合于治疗局限性腹主动脉夹层、主髂分叉处直径较小的腹主动脉瘤等病变。