420 MPa级高强钢焊接圆钢管柱屈曲的试验研究

研究由420 MPa级高强钢(HSS)制成的焊接圆钢管柱的屈曲性能。对24个直径为273 mm、厚度为6 mm的轴心受压柱试件进行试验,测量包括轴向弯曲和荷载偏心距在内的初始几何缺陷。介绍并详细讨论关于屈曲模式和承载力的试验结果,并建立非线性有限元模型,对不同截面大小、由HSS 60制成的焊接圆钢管进行进一步参数分析。将有限元和试验结果与中国、欧洲以及美国规范中已有的柱设计曲线相比较。数值结果显示,可以采用GB 50017—2003、欧洲规范EC 3和ANSI/AISC360-10中的设计公式所计算的数值。此外,为了进一步提升设计效率,提出一条可用于这种高强钢焊接圆钢管设计、基于缺陷系数为0.17的欧洲规范EC 3公式的柱设计曲线。     

1000 MPa及以上级高强钢焊接性研究现状

通过对1 000 MPa及以上高强钢焊接性的分析研究,概述了1 000 MPa及以上高强钢焊接的研究现状,分析了不同焊接工艺条件对高强钢焊接组织与性能的影响,并对今后高强钢焊接的发展方向提出了建议。     

Q345B钢的焊接工艺设计及焊接工艺评定实践

为严格控制焊接质量,对桥梁用Q345B钢焊接工艺进行设计并对所制定焊接工艺进行评定,试样结果表明所制定焊接工艺正确,为今后编制焊接工艺规程提供了依据.     

潮湿环境高强钢焊接工艺及工程应用

针对高强钢淬硬性大和潮湿的气候特点,选择低氢型焊接材料,根据不同钢板材质、板厚,大气温度和湿度制订具体的加热和焊接工艺,采取有效措施降低焊接区域湿度影响,控制焊缝层间温度,规范焊工的操作过程,及时进行焊后消氢处理。最终实现高强钢在空气湿度90%以上的环境下进行顺利焊接,并针对潮湿环境下高强钢焊接工艺进行阐述。     

屈服强度1300MPa超高强钢焊接抗裂性试验研究

对工程机械用屈服强度1300MPa超高强钢焊接抗裂性进行了试验研究。采用搭接接头（CTS）焊接裂纹试验、斜Y型坡口抗裂性试验、巴东抗裂试验3种抗裂性试验测试了不同厚度的Q1300E钢对冷裂纹的敏感性,对比了3种试验情况,并进行了产品吊臂的模拟试验。研究结果表明,巴东抗裂试验的结构拘束度很大,是一种验证高强钢焊接抗裂性的可靠试验方法;Q1300E钢具有较明显的冷裂倾向,8mm及15mm两种板厚的Q1300E钢分别采用110℃及125℃预热温度可避免冷裂纹产生。该研究对高强钢结构件焊接抗裂性研究具有较强参考意义。     

轴压下460 MPa级高强度钢材焊接截面短柱的局部屈曲

由于钢屈服强度的提高,与普通强度钢(NSS)制成的型钢相比,高强度钢焊接而成的型钢更薄、更轻。这导致了钢板构件的宽厚比更大,且局部屈曲对受压构件的影响也更大。对由4个箱形截面构件和9个工型截面构件组成的钢短柱(钢材为Q460)进行轴压试验,建立对初始缺陷进行精确模拟的有限元模型。建模结果通过了试验和理论分析的验证。将试验和数值结果与通过不同规范中的设计方法得出的极限应力相比较,结果显示,对于箱形截面钢板构件,这些设计方法高估了其局部屈曲的极限应力,导致结果不够安全。而设计方法又低估了工字型截面部件翼缘的极限应力,特别是那些宽厚比相对大的工字型截面部件。     

不同试验方法对630MPa级高强钢筋粘结-锚固影响研究

为研究高强钢筋与混凝土粘结性能采用拉拔试验和梁式试验,制作了15根630MPa级高强钢筋中心拉拔试件和15根梁式试件,考虑锚固长度、钢筋直径两个影响因素,从破环形态、粘结强度、粘结滑移性能等方面进行了对比分析。结果表明：在相同条件下,拉拔试件破坏形态与梁式试件类似;粘结滑移曲线变化规律相近;高强钢筋与混凝土的平均粘结强度随锚固长度和钢筋直径的增大而减小;拉拔试验测得的粘结锚固强度要高于梁式试验测得的粘结锚固强度;梁式试验比拉拔试验在极限荷载时的滑移量小,梁式试件受力更符合实际受力情况,但梁式试件制作难度比较大;比较梁式试验和中心拉拔试验所得粘结强度,给出两种试件粘结强度的关系。     

500MPa级钢筋在高强混凝土中的锚固性能试验研究

进行了15组45个中心置筋拉拔试件试验,混凝土立方体抗压强度实测值在66.6MPa～89.2MPa,钢筋为HRB500,研究混凝土强度和相对保护层厚度对粘结锚固性能的影响。试验表明:66.6MPa～77.2MPa的试件极限粘结强度随混凝土抗压强度的提高而增大,而78.7MPa及以上试件极限粘结强度停止增长并有所降低;试件的极限粘结强度随相对保护层厚度c/d的增长近似呈线性增长;高强混凝土与普通混凝土相比劈裂后粘结强度的增长程度不明显。将极限粘结强度试验值与高强混凝土粘结强度公式计算值对比可知,锚筋直径为25mm,混凝土强度89.2MPa试件试验值较公式值偏小。     

超高强钢薄板CMT焊接工艺研究

为了降低工程机械自重,推广使用超高强钢薄板从而减小使用材料的厚度是有效的途径之一。传统薄板的连接主要采用混合气体保护焊（MAG焊）。但是,由于MAG焊热输入量大,飞溅相对较多等缺点,造成焊缝缺陷较多或成型不良。本文采用冷金属过渡焊CMT代替MAG焊,利用CMT焊接热输入小,无飞溅的特点改善了工件焊接质量。本文研究了CMT焊接速度、送丝速度、弧长修正系数对超高强薄板焊接质量的影响,优化获得的工艺方案和规范参数用于实际生产,取得了良好的效果。     

G550级高强薄板钢材的材性及应用

近年来,壁厚不大于1 mm、屈服强度达550 MPa的高强冷弯薄壁型钢已在国外实际工程中开始应用.为了促进高强冷弯薄壁型钢结构在中国的推广应用,验证高强钢材对中国冷弯薄壁型钢结构技术规范相关设计规定的适应性,本项目开展了G550级冷弯薄壁型钢的材性和轴压构件受力性能的系列试验研究,以期提出适用G550级钢材构件的设计计算建议.首先对t为0.48,0.60,0.75,1.00 mm 4种厚度G550级冷轧镀层薄板进行了材性试验研究,考察和分析了其材性特征,讨论了在中国推广和应用高强冷弯薄壁型钢时可能存在的主要问题及相应对策.材性试验结果可用于构件的试验研究和分析.     

II级粉煤灰配制高强混凝土的正交试验研究

通过双掺II级粉煤灰与S95级矿粉来配置高强混凝土,并采用设计正交试验的方法将粉煤灰掺量、矿粉掺量和高效减水剂掺量定为影响高强混凝土抗压强度和坍落度的主要因素进行试验分析,确定配置高强混凝土各组分间合理的掺量,并分析了高强混凝土3、7、28d强度。结果表明在无早期强度要求时,II级粉煤灰最佳掺量为胶凝材料的15%~20%左右,S95级矿粉最佳掺量为胶凝材料的15%左右,减水剂的最佳掺量为胶凝材料的2.0%。     

型钢高强高性能混凝土框架拟动力试验研究

采用基于位移控制的多点地震记录输入的拟动力试验方法,进行了一榀1/4比例的两跨3层型钢高强高性能混凝土框架拟动力试验。研究了地震作用下该结构的动力反应、层间位移和楼层耗能的分布方式、结构破坏机理及裂缝形态,测试了结构在不同阶段的频率与阻尼比。试验结果显示型钢高强高性能混凝土框架具有良好的耗能能力和变形能力,框架实现了较为理想的梁铰屈服机制,楼层变形呈倒三角形分布,结构阻尼比略低于普通型钢混凝土框架结构的阻尼比。最后,基于考虑损伤退化的型钢高强高性能混凝土框架滞回模型对试验模型进行了弹塑性时程分析,并分析了计算与试验结果产生差异的原因。     

400 MPa和500 MPa钢筋疲劳强度规范的研究

400 MPa和500 MPa是一种新型的超级钢钢筋,主要应用于高强度钢筋混凝土中.在现有的关于钢筋混凝土应用规范中没有钢筋疲劳强度的使用规定.根据国外的钢筋疲劳试验标准,并结合国内的工程实践,确定钢筋疲劳强度试验的试验标准和试验的方法.并对400 MPa和500MPa超级钢的Φ16和Φ25的钢筋疲劳进行疲劳试验,验证了提出的试验标准和试验方法是合理的.同时研究钢中晶粒度对疲劳强度的影响,为钢筋应用规范提供依据.     

Residual stress of 460 MPa high strength steel welded i section: Experimental investigation and modeling

A reliable estimation of residual stress within steel sections is important in steel structural design and construction, especially for high strength steel which has been increasingly used in recent years. An experimental investigation was conducted in this paper to quantify the residual stresses in 460 MPa steel welded I sections using sectioning method. The magnitude and distribution of both compressive and tensile residual stresses were obtained based on 1972 sets of original data measured from eight different sections. The effects of width-thickness ratios of the flange and web, steel plate thickness, weld type and interaction of the flange and web were investigated. It was found that the compressive residual stress magnitude was largely related to the sectional dimension, while no direct correlation was found with the weld type and size for tensile ones. No residual stress interaction between the flange and web was identified because of the stress equilibrium within each individual part. In addition, a distribution model was proposed in this paper and well described the experimental results, which can be used to investigate and design the buckling behavior of 460 MPa high strength steel members.     

Experimental investigation of the overall buckling behaviour of 960 MPa high strength steel columns

Investigations of the mechanical performance of high strength steel structures have become a research hotspot in civil and structural engineering, and existing experimental studies of their overall buckling behaviour have hitherto focused mainly on columns fabricated from either 460 MPa or 690 MPa steels. The present study describes an experimental programme including six pin-ended 960 MPa steel columns under axial compression. Both welded I- and box-section specimens are considered. The initial geometric imperfections and cross-sectional residual stresses are reported, with the axial loading, deformation and the strain distributions at the mid-length section being monitored during the testing. The buckling mode is clarified, and the buckling capacity is compared with design results according to current national design codes. Based on the experimental results, a finite element model is described and validated, and then used to perform a large number of parametric studies, considering different cross-sectional dimensions and column slendernesses. It is found that all specimens failed by overall flexural buckling, and the corresponding column curves in current design codes underestimate the dimensionless buckling strength of 960 MPa steel columns. Higher and more adequate column curves are suggested for such columns, and new column curves are proposed based on a non-linear fitting of the parametric results.     

960 MPa高强度钢材轴压构件整体稳定性能试验研究

为研究960 MPa高强度钢材轴压构件的整体稳定性能,对6个焊接工字形和等边箱形截面试件进行了静力试验研究,测量了试件的几何初弯曲、荷载初偏心以及截面残余应力分布等初始缺陷,分析了试件的失稳破坏形态,得到了整体稳定承载力,并与规范设计曲线进行了对比分析。利用试验结果验证了有限元分析模型,并进行参数分析。研究结果表明：试件的破坏模态均为整体弯曲失稳,除两个几何初始缺陷过大的试件外,其他试件的整体稳定系数试验值均明显高于规范设计值;参数分析结果表明,960 MPa钢材焊接截面轴压构件的整体稳定系数较普通钢材显著提高,建议采用GB 50017-2003中的a类柱子曲线设计此类轴压构件,同时拟合了960 MPa高强度钢材的柱子曲线公式。     

Overall buckling behavior of 460 MPa high strength steel columns: Experimental investigation and design method

Overall buckling behavior of compression columns is one of the most important research subjects in steel structures, especially for high strength steel which has been increasingly applied in recent years. An experimental investigation was carried out to study the overall buckling behavior of 460 MPa high strength steel compression members. Totally twelve columns including welded box and I-sections were comprised. The initial imperfections such as the residual stress, initial bending and loading eccentricity were all measured. Based on experimental results the buckling deformation and capacity were investigated. A finite element model was established and further validated by comparing with the test data in both present study and other previous researches, in which initial imperfections were taken into account. A large number of columns with various section dimensions and lengths were calculated by using the validated model, and their buckling capacities were compared with design values according to different steel structures specifications. It was found that the nondimensional buckling strength of such 460 MPa high strength steel columns were significantly improved compared to normal strength steel columns, and corresponding column curves and design formulae were suggested.     

泉州世界贸易中心高强度厚钢板焊接工艺制定

本文结合工程实例针对高强度厚钢板焊接的难点,制定了详细的焊接工艺,对高强度厚钢板的焊接方法及焊材料的选择、焊接顺序、焊接工艺参数等方面做了详细阐述,经试验检测及本工程实践证明,所制定的焊接工艺是合理的,有效的保证了焊接质量。