【作者】 金鑫；

【导师】 舒赣平；

【作者基本信息】 东南大学 ， 土木工程， 2019， 硕士

【摘要】 不锈钢凭借耐腐蚀性强、表观性好、力学性能优的优势,在土木工程建设领域具有巨大的应用前景,是高性能绿色建筑材料的代表,契合国家中长期发展战略,是严苛环境下工程结构材料的优选方案。目前关于不锈钢结构的相关研究及应用主要集中于奥氏体型和双相体型不锈钢,该类材料耐腐蚀性强,但价格偏高且强度低,进而造成了不锈钢结构初期投资高,难以推广。近年来,国内外先后研发出新型高强不锈钢(S600E、304D等),该类材料的突出特点为强度高、价格低,在不锈钢结构中具有极强竞争力和推广应用前景。基于此现状,本文通过试验研究和数值计算,对新型高强不锈钢S600E焊接轴心受压箱形和工字形构件的残余应力分布、局部稳定、整体稳定进行了研究,提出了构件受压承载力的合理设计建议。本文工作主要包括:(1)进行了S600E不锈钢材料成分分析并开展24组不同方向材料拉伸试验,得到了新型高强不锈钢S600E实测拉伸材料力学性能的重要参数,验证了两阶段R-O本构模型的可行性。(2)采用割条法对S600E焊接成型的10个工字形截面和6个箱形截面不锈钢构件的残余应力大小和分布形态进行试验测量(1000条带)。焊接不锈钢构件截面残余应力峰值低于材料的名义屈服强度,且截面存在较宽的残余拉压应力转换区。工字形截面残余压应力峰值随板件宽厚比变化不明显,残余拉应力的分布范围与板件宽度相关而与厚度无关;箱形截面试件组成板件残余压应力的峰值与板件的宽厚比直接相关,板件的宽厚比越大,残余压应力峰值越小,基于测量结果提出适用于S600E的残余应力建议简化模型。(3)进行了16个两端固接的S600E焊接不锈钢短柱局部稳定试验,截面包括工字形截面(10个)和箱形截面(6个),得到新型高强不锈钢S600E焊接构件的局部稳定承载力和破坏特性。采用《美国冷成型不锈钢设计规范》(SEI/ASCE 8-02)、《欧洲不锈钢结构设计规范》(EN 1993-1-4:2006+A1:2015)、中国《不锈钢结构技术规程》(CECS410:2015)中的相关规定对不锈钢结构局部稳定承载力进行计算,并与试验值对比,结果表明:《不锈钢结构技术规程》(CECS410:2015)、《欧洲不锈钢结构设计规范》(EN 1993-1-4:2006+A1:2015)偏保守,《美国冷成型不锈钢设计规范》(SEI/ASCE 8-02)不宜直接用于S600E焊接不锈钢轴压构件的设计计算。建立并验证了短柱有限元模型的准确性。对焊接不锈钢轴压构件局部稳定进行186个数值算例,提出加劲板件和非加劲板件的受压临界宽厚比限值的建议值,修正了局部稳定承载力的有效宽度法,利用了板件屈曲后强度及屈服后强化。(4)进行了2个两端铰接S600E焊接不锈钢柱的整体稳定试验,并通过对比验证了有限元模型的适用性。根据有限元结果对国内外规范计算方法进行评估,表明规范计算公式存在局限性。对影响整体稳定的几何初始缺陷、截面形式、残余应力展开数值分析,得到了适用于S600E材料的柱子曲线。本文的研究成果可以为《不锈钢结构技术规程》(CECS410:2015)的修订及《高强不锈钢结构技术标准》的编制提供试验和理论依据。更多还原

【Abstract】 With its remarkable corrosion resistance,good appearance and excellent mechanical properties,stainless steel has promising prospect in structural engineering applications.As a high performance environmentalfriendly building material,it fits the country’s medium and long-term development strategy and becomes the best choice for the new material in the harsh environment.At present,the related research and application of stainless steel structure mainly focus on austenitic and duplex stainless steel.This kind of material has strong corrosion resistance,but the price is high and the strength is low,which causes the initial investment of stainless steel structure to be high and difficult to promote.In recent years,new high-strength stainless steels(S600E,304 D,etc.)have been developed at home and abroad.The outstanding characteristics of this kind of materials are high strength and low price,and they have strong competitiveness and popularization and application prospects in stainless steel structures.Based on this situation,this paper studies the residual stress distribution,local stability and overall stability of the new high-strength stainless steel S600 E welded axial compression box and I-shaped components through experimental research and numerical calculation,and puts forward reasonable design suggestions.The following three sections were covered in this dissertation,(1)The composition analysis of S600 E stainless steel was carried out and 24 groups of tensile tests were carried out in different directions.The important parameters of the mechanical properties of the new highstrength stainless steel S600 E tensile material were obtained.The feasibility of the two-stage R-O constitutive model was verified.(2)The residual stress magnitude and distribution pattern of 10 I-shaped sections and 6 box-section stainless steel members welded by S600 E were tested by cutting strip method(1000 strips).The nominal yield strength of the material is higher than the peak residual stress of the welded stainless steel member,and there is a wide residual tensile and compressive stress transition region in the cross section.The peak value of the residual compressive stress of the I-sections does not change significantly with the width-to-thickness ratio of the plate.The distribution range of the residual tensile stress is related to the width of the plate and is independent of the thickness.The peak value of the residual compressive stress of the cross-section is directly related to the width-thickness ratio of the plate.The larger the aspect ratio of the plate,the smaller the peak value of the residual compressive stress.Based on the measurement results,a simplified model for residual stress recommendation for S600 E is proposed.(3)16 stub columns tests on welded stainless steel sections were carried out,and the local stable bearing capacity and failure characteristics of the stainless steel S600 E welded members were obtained.Based on the material properties obtained from tension tests,values of the calculation formula of the bearing capacity in the 3 specifications(“Specification for the Design of Cold-Formed Stainless Steel Structural Members”(SEI/ASCE 8-02),“Eurocode 3 –Design of Steel Structures-Part 1-4: General Rules-Supplementary for Stainless Steel”(EN 1993-1-4:2006+A1:2015),“Technical Specification for Stainless Steel Structures”(CECS410: 2015))are compared with the experimental results.It indicates that “Technical Specification for Stainless Steel Structures” and European norms are conservative,and American standards should not be directly used for the design calculation of S600 E welded stainless steel axial members.The accuracy of the short-column finite element model is verified by comparing the finite element with the experimental results.Numerical simulations on a total of 186 stub columns of the local stability of welded stainless steel axial members were carried out.The evaluation of the existing design method was used to propose new validated slenderness limits for both internal and outstand elements subject to compression have been presented.Modifications to the effective width method(EWM)have been proposed for treatment of local buckling.(4)The overall stability test of two welded stainless steel columns was carried out,and the applicability of the finite element model was verified by comparison.According to the finite element results,the domestic and foreign normative calculation methods are evaluated,which shows the limitations and shortcomings of the normative calculation formula.The numerical analysis of the main factors affecting the overall stability was carried out,and the column curve suitable for the S600 E material was obtained.The research results of this paper can provide experimental and theoretical basis for the revision of "Technical Regulations for Stainless Steel Structures"(CECS410:2015)and the preparation of "Technical Standards for High-strength Stainless Steel Structures".更多还原