奥氏体不锈钢焊接工字型截面轴压构件整体稳定性能试验研究

为了研究奥氏体不锈钢材料的轴心受压构件的整体稳定性能,对11根奥氏体型不锈钢焊接工字形截面试件进行了轴心受压试验研究,其中5根采用强轴失稳模式,6根采用弱轴失稳模式。根据试验前测量得到的试件的几何初弯曲和试验过程中量测得到的荷载初偏心,分析了该类型构件的失稳模态和整体稳定性能承载能力,并将试件的试验数据计算结果与现行欧洲不锈钢结构规范和中国钢结构规范进行了对比,表明欧洲不锈钢规范偏保守,而中国钢结构规范较不安全。     

Q460高强钢焊接箱形截面轴压构件整体稳定性能研究

为研究高强度钢材轴心受压钢柱的整体稳定性能,对5个国产Q460钢材焊接箱形截面柱进行了轴心受压试验研究。试验对试件的几何初弯曲、荷载初偏心以及截面的纵向残余应力分布均进行了测量。基于试验结果,分析了该类钢柱的失稳破坏形态和整体稳定承载力,建立了有限元分析模型并对试验结果进行模拟计算。研究结果表明：试件破坏模态均为整体弯曲失稳形态,大部分试件稳定承载力高于规范设计值;有限元分析模型能够准确地考虑几何初始缺陷和残余应力的影响,计算结果与试验结果吻合良好;通过与国内外钢结构设计规范的对比,提出了国产Q460高强钢焊接箱形截面轴压构件整体稳定设计的建议方法,即可以统一采用我国或欧洲规范的b类曲线进行设计,而不需要按板件宽厚比大小进行分类。     

不锈钢焊接工形截面压弯构件试验研究

为了研究不锈钢焊接工形截面压弯构件的静力承载性能,共设计了20根不锈钢压弯构件,并进行了压弯试验。其中10根为奥氏体不锈钢构件,包括5根绕强轴失稳试件和5根绕弱轴失稳试件,另外10根为双相型不锈钢构件,同样包括绕强轴和弱轴失稳试件各5根。试件长细比在50~120之间,设计荷载偏心距分别为50、60 mm和70 mm,并在试验前测量了试件的初始弯曲和荷载初偏心。根据试验结果,分析了试件的破坏形态、荷载-位移曲线、荷载-应变曲线及承载力,并将试验结果分别与我国现行规范CECS 410:2015《不锈钢结构技术规程》和欧洲规范EN 1993-1-4中不锈钢压弯构件承载力的计算值进行了对比。结果表明:所有构件均发生平面内的整体弯曲失稳,且整体失稳前没有发现明显的局部板件屈曲;构件承载力随着偏心距、长细比的增大而降低;对于不锈钢焊接工字形截面压弯构件,两部规范的计算结果均偏于安全。     

奥氏体型S30408不锈钢角焊缝连接承载性能有限元分析

结合材性试验获得的不锈钢母材和焊缝金属材料本构关系模型,使用ANSYS有限元软件对奥氏体型S30408不锈钢角焊缝连接的承载性能进行了非线性有限元模拟,并将模拟结果与不锈钢正面角焊缝连接试件和侧面角焊缝连接试件拉伸试验结果进行了对比,验证了有限元模型的有效性。利用经试验验证的有限元模型对角焊缝承载力影响因素进行了参数分析,并将有限元模拟值与按照美国规范SEI/ASCE 8-02、欧洲规范EN 1993-1-4,以及中国《不锈钢结构技术规程》(CECS 410:2015)计算求得的规范设计值进行了对比,得出了承载力模拟值与各国规范设计值的比值,结果可为不锈钢设计规范的完善和工程应用提供参考。     

奥氏体型不锈钢焊接箱形截面轴压构件整体稳定性能试验研究

为了研究奥氏体型不锈钢材轴心受压构件的整体稳定性能,对6根奥氏体型不锈钢焊接箱形截面柱进行了轴心受压试验研究,在试验前对试件的几何初弯曲进行了测量,在试验过程中对荷载初偏心进行了量测。基于试验结果,分析了该类型构件的失稳破坏形态和整体稳定承载力,并与欧洲钢结构规范和中国钢结构规范进行了对比。结果表明此次试验数据高于欧洲钢结构规范和中国钢结构规范的设计曲线,设计曲线较为保守。     

焊接不锈钢工字形截面梁整体稳定性试验研究

不锈钢材料在建筑结构中已得到广泛应用。为研究焊接不锈钢梁的整体稳定性能,进行了纯弯状态下的静力试验研究。试验包括10个试件,材料类型为奥氏体型316。截面类型采用了双轴对称和单轴对称工字形截面,试件的端部约束采用夹支,试验过程持续加载,直至达到试件的承载力峰值。基于试验结果,研究了焊接不锈钢梁的失稳破坏形态和极限承载力;对比了试验极限弯矩与理论弹性弯矩、塑性弯矩的差异,并将试验结果与有限元分析结果进行了对比。结果表明：试件的承载能力随着跨度的增大而减小,有限元分析能够准确预测试件的承载力,与试验结果吻合良好。     

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。     

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。     

不锈钢焊接工字形截面梁整体稳定性分析

基于国内外已有的不锈钢焊接工字形截面梁整体稳定性的计算方法,包括美国SEI/ASCE 8-02中的方法、欧洲EN 1993-1-4中的方法和王元清提出的方法,采用有限元方法对不锈钢焊接工字形截面梁的整体稳定性进行分析,并用不锈钢焊接工字形截面梁已有的试验数据对有限元模型的准确性进行验证,在此基础上,对不锈钢焊接工字形截面梁进行参数化分析。分析表明:对梁整体稳定承载力影响的因素从大到小依次为材料名义屈服强度、荷载类型、截面类型和焊接残余应力;在参数化分析的基础上,提出基于修正正则化长细比的Perry公式型整体稳定系数表达式;将所提出的计算方法、国内外现有的计算方法与试验数据进行了对比,结果表明受试验中边界条件的影响,试验值高于计算方法的计算值,与其他方法相比,所提出的计算方法与有限元计算结果吻合更好,可以用于计算焊接工字形截面梁的整体稳定承载力。     

冷弯经济型双相不锈钢弯构件试验研究及数值分析

对冷弯经济型双相不锈钢受弯构件进行试验研究及数值分析。试件由屈服强度(σ0.2)为450MPa的经济型双相不锈钢板材冷轧成型。对方形和矩形截面空心型材试件进行绕强轴和弱轴的弯曲试验。利用取样试验得到的材料性能建立有限元模型,并利用弯曲试验结果对其进行验证。结果表明,该模型可以准确预测经济型双相不锈钢抗弯构件的性能。利用有限元模型进行了大量参数研究。利用现有的各种设计准则,如美国规范、澳大利亚/新西兰规范、欧洲规范以及直接强度法计算冷弯不锈钢的设计强度,并与经济型双相不锈钢梁的试验和数值分析结果以及可用的数据进行对比。为评估这些设计准则的可靠性,进行了可靠性分析。结果表明,现有设计准则计算经济型双相不锈钢受弯构件的设计强度时偏于保守。对美国规范、澳大利亚/新西兰规范、欧洲规范以及直接强度法进行了修正,提高了这些设计准则的精度。     

Stub column tests of thin-walled complex section with intermediate stiffeners

A series of stub column tests on complex sections with intermediate stiffeners is presented in this paper. Initial geometric imperfections and material properties of the test specimens were measured. It is shown that the intermediate stiffeners could effectively enhance the local buckling stress of thin-walled sections. The test strengths are compared with the design strengths calculated using the direct strength method in the North American Specification and Australian/New Zealand Standard for cold-formed steel structures. It is shown that the direct strength method using finite strip method to obtain the buckling stresses is very conservative. Therefore, finite element method was used to predict the elastic buckling stresses. It is shown that the design strengths calculated using direct strength method based on the buckling stresses obtained from finite element analysis results generally agree with the test results well.     

A new design method for stainless steel columns subjected to flexural buckling

The objective of this paper is to develop a design method for stainless steel columns subjected to flexural buckling. In this method, the strength curve for every type of stainless steel in common use is generated by using the base strength curves and a slenderness conversion formula. A validated finite element model is employed to generate the strength curves for different types of stainless steels. According to the strain hardening exponent n in the Ramberg-Osgood material model, cluster analysis is conducted to separate these strength curves into two groups. In each group, one type of material parameter is selected as the base material and the corresponding strength curve is expressed in the form of a modified Perry formula that serves as the base strength curve. A slenderness conversion formula is derived for any two stainless steel columns with the same section type and boundary conditions, but with different types of stainless steel. Based on the base strength curves and the slenderness conversion formula, the strength curve for every type of stainless steel in common use can be generated. The predictions of the proposed method show a good agreement with the results of the finite element analysis.     

Experimental and numerical investigation of cold-formed lean duplex stainless steel flexural members

Experimental and numerical investigation of cold-formed lean duplex stainless steel flexural members is presented in this paper. The test specimens were cold-rolled from flat plates of lean duplex stainless steel with the nominal 0.2% proof stress of 450 MPa. Specimens of square and rectangular hollow sections subjected to both major and minor axes bending were tested. A finite element model has been created and verified against the test results using the material properties obtained from coupon tests. It is shown that the model can accurately predict the behaviour of lean duplex stainless steel flexural members. An extensive parametric study was carried out using the verified finite element model. The test and numerical results as well as the available data on lean duplex beams are compared with design strengths predicted by various existing design rules, such as the American Specification, Australian/New Zealand Standard, European Code and direct strength method for cold-formed stainless steel. Reliability analysis was performed to evaluate the reliability of the design rules. It is shown that these current design rules provide conservative predictions to the design strengths of lean duplex stainless steel flexural members. In this study, modified design rules on the American Specification, Australian/New Zealand Standard, European Code and direct strength method are proposed, which are shown to improve the accuracy of these design rules in a reliable manner.     

不锈钢冷成型管截面轴心受压构件的有限元分析

采用有限元软件ANSYS对不锈钢冷成型管截面轴心受压长柱进行模拟,有限元模型中考虑不锈钢材料的非线性本构关系、冷加工效应、构件的初始缺陷以及构件中的残余应力。将模拟结果与国内外的试验数据进行对比。对比表明:有限元模型能够准确地模拟不锈钢构件的受力全过程,模拟平均误差小于5%;对影响不锈钢轴心受压构件受力性能的因素进行分析,分析表明:方矩管截面的转角区冷加工效应,不锈钢材料力学性能参数变化以及构件的整体缺陷取值对构件的整体稳定性能影响较大,而不锈钢构件的截面对稳定系数影响很小。分析结论可作为建立不锈钢轴心受压构件稳定承载力设计公式的参考。     

Design of cold-formed steel unequal angle compression members

Cold-formed steel unequal angles are non-symmetric sections. The design procedure of non-symmetric sections subjected to axial compression load could be quite difficult. The unequal angle columns may fail by different buckling modes, such as local, flexural and flexural–torsional buckling as well as interaction of these buckling modes. The purpose of this study is to investigate the behaviour and design of cold-formed steel unequal angle columns. A nonlinear finite element analysis was conducted to investigate the strength and behaviour of unequal angle columns. The measured initial local and overall geometric imperfections as well as the material properties of the angle specimens were included in the finite element model. The finite element analysis was performed on fixed-ended columns for different lengths ranged from stub to long columns. It is demonstrated that the finite element model closely predicted the experimental ultimate loads and the behaviour of cold-formed steel unequal angle columns. Hence, the model was used for an extensive parametric study of cross-section geometries. The column strengths obtained from the parametric study were compared with the design strengths calculated using the North American Specification for cold-formed steel structural members. It is shown that the current design rules are generally unconservative for short and intermediate column lengths for the unequal angles. Therefore, design rules of cold-formed steel unequal angle columns are proposed.     

Q460高强钢焊接工字形截面简支梁整体稳定性能与设计方法研究

为研究Q460高强钢焊接工字形截面简支梁的整体稳定性能,对跨中无侧向支撑的3个双轴对称和6个单轴对称焊接工字形截面简支梁进行了整体弯扭屈曲试验。实测了试件的截面残余应力和初始几何缺陷,并分析其整体弯扭屈曲变形特征和稳定承载力。建立考虑残余应力和初始几何缺陷的有限元模型对简支梁受力进行了模拟,模拟结果与试验结果吻合良好,基于试验验证的有限元模型计算了大量不同截面尺寸和跨度的Q460高强钢焊接工字形截面简支梁的整体稳定承载力。将试验和有限元参数分析结果与GB 50017—2017《钢结构设计标准》、JGJ/T 483—2020《高强钢结构设计标准》、欧洲规范EN 1993-2005和美国规范ANSI/AISC 360-2016的简支梁整体稳定系数公式的计算结果进行比较,结果表明GB 50017—2017和ANSI/AISC 360-2016的计算结果偏于不安全,EN 1993-2005的计算结果过于保守,JGJ/T 483—2020的计算结果偏于安全且最为接近。最后,在JGJ/T 483—2020的简支梁整体稳定系数计算公式基础上引入增大系数,并根据截面高宽比的不同,取用不同的长细比指数对该公式予以修正,修正后的公式更适用于Q460高强钢焊接工字形截面简支梁的设计计算。     

Structural performance of cold-formed high strength stainless steel columns

This paper describes an accurate finite element model for the structural performance of cold-formed high strength stainless steel columns. The finite element analysis was conducted on duplex stainless steel columns having square and rectangular hollow sections. The columns were compressed between fixed ends at different column lengths. The effects of initial local and overall geometric imperfections have been taken into consideration in the finite element model. The material nonlinearity of the flat and corner portions of the high strength stainless steel sections were carefully incorporated in the model. The column strengths and failure modes as well as the load-shortening curves of the columns were obtained using the finite element model. Furthermore, the effect of residual stresses in the columns was studied. The nonlinear finite element model was verified against experimental results. An extensive parametric study was carried out using the verified finite element model to study the effects of cross-section geometries on the strength and behaviour of cold-formed high strength stainless steel columns. The column strengths predicted from the parametric study were compared with the design strengths calculated using the American Specification, Australian/New Zealand Standard and European Code for cold-formed stainless steel structures. The results of the parametric study showed that the design rules specified in the American, Australian/New Zealand and European specifications are generally conservative for cold-formed high strength stainless steel square and rectangular hollow section columns, but unconservative for some of the short columns.     

腹板开矩形孔复杂卷边冷弯槽钢梁局部屈曲性能及直接强度法研究

为了研究腹板开孔复杂卷边冷弯槽钢梁的局部屈曲性能，以及探究北美冷弯型钢结构设计规范(AISI S100-2016)中腹板开孔冷弯槽钢梁局部屈曲直接强度法计算公式的可靠性，对孔高比(孔洞高度与腹板高度的比值)分别为0、0.2、0.4、0.6和0.8的10个腹板开矩形孔复杂卷边冷弯槽钢梁纯弯试件进行了静力试验研究。试验结果表明，开孔和不开孔试件均发生以局部屈曲为主的屈曲破坏模式，与不开孔试件相比，开孔试件的受弯承载力下降，且下降幅度随孔高比的增大而增大。利用ANSYS有限元程序对试验进行了模拟分析，分析结果与试验结果吻合良好；在此基础上，采用经试验验证的有限元模型，通过变换腹板高度、板厚和孔高比开展了有限元参数分析，并根据有限元参数分析结果对已有腹板开孔冷弯槽钢梁的弹性局部屈曲临界应力近似计算公式进行了修正。基于试验结果、有限元参数分析结果以及修正的弹性局部屈曲临界应力近似计算公式，对AISI S100-2016中开孔冷弯槽钢梁发生以局部屈曲为主破坏时的直接强度法计算公式进行了修正。