冷弯薄壁C型钢轴压短柱承载力计算方法的改进

用我国规范有效宽度法求得的冷弯薄壁型钢短柱构件极限承载力高于试验结果,倾向于不安全。所以,通过分析提出,按照《冷弯薄壁型钢结构技术规范》GB50018-2002中的有效宽度法计算组合截面冷弯薄壁型钢受压构件承载力时,可以对计算结果乘以一个修正系数以示其原结果的不安全程度。由于有效宽度法在计算试件极限承载力时存在不安全性,因此本文引入另一种适用于冷弯薄壁型钢构件的计算方法,即直接强度法(Direct Strength Method,DSM)。将直接强度法和有效宽度法计算求得的短柱极限承载力与试验结果进行对比,结果表明,直接强度法的计算结果与试验值更为吻合,为使其结果更加经济、安全,本文提出适用于计算组合截面冷弯薄壁型钢受压构件承载力的直接强度法建议公式。     

高强冷弯薄壁型钢帽型截面连续檩条受力性能研究

对24根两种截面形式为TS40和TS61的G550高强冷弯薄壁型钢帽型截面两跨连续檩条进行了受弯性能试验研究,并在此基础上利用有限条软件CUFSM结合直接强度法对两种截面两跨的试验檩条进行了极限承载力的计算,计算结果与试验结果吻合较好。同时,采用非线性有限单元法对各试件进行模拟分析,并与试验结果进行比较。结果表明:大部分试件的试验极限承载力均略高于直接强度法计算得到的极限承载力,用直接强度法进行高强冷弯薄壁型钢帽型截面两跨连续檩条的设计是可行的,且计算结果偏于安全;有限元分析得到的各试件极限承载力和试验结果吻合较好,有限元分析方法能很好地模拟高强冷弯薄壁型钢帽型连续檩条的受力性能,计算结果具有较高的精确度。     

冷弯薄壁型钢四肢拼合立柱轴压承载力设计方法

建立了考虑材料、几何和接触非线性的有限元模型,在对冷弯薄壁型钢四肢拼舍截面立柱的轴压性能试验试件进行模拟分析,验证有限元方法正确性的基础上,对考虑长细比、截面翼缘宽厚比等因素的一系列试件进行了数值分析,并得到其轴压承载力.在相关规范“有效宽度法”和“直接强度法”的基础上,提出了冷弯薄壁型钢四肢拼合截面立柱轴压承载力的设...     

冷弯薄壁型钢多肢拼合柱轴压承载力计算方法对比分析

以由单肢C形和U形截面拼合而成的冷弯薄壁型钢拼合截面轴压柱试验结果为基础,对采用我国现行规范与征求意见稿中有效宽度法计算的30根(6种截面,5种长度)轴压构件的极限承载力进行了对比分析。基于有效宽度法,提出了针对组合截面承载力的计算方法。比较了我国规范征求意见稿与美国规范中直接强度法的不同,基于美国规范的直接强度法利用CUFSM有限元软件对拼合截面进行建模分析,取消螺钉拼合连接部分的板件边界,将拼合截面作为一个整体进行分析,拼合部分厚度在1.0t至2.0t。对比发现:对于开口截面,厚度为1.0t时计算值与试验值之比的平均值更接近于1.0;对于闭合截面,厚度为1.2t时计算值与试验值之比的平均值更接近于1.0。     

薄壁方钢管混凝土短柱承载性能非线性有限元分析

采用ANSYS软件,对薄壁方钢管混凝土短柱的承栽性能进行非线性有限元分析.考虑轴压作用下带肋与不带肋两种截面形式的薄壁方钢管混凝土短柱力学性能,并得出其破坏模态,计算结果与试验结果吻合较好.针对该类构件,探讨加劲肋和钢管强度对其承载力的影响.结果表明,设置加劲肋能有效提高薄壁方钢管混凝土短柱的轴压承载力,与不带肋短拄相...     

带腹板加劲肋高强薄壁钢柱局部稳定研究

为提高局部稳定承载力,提出了带腹板加劲肋的高强薄壁钢柱的截面型式,并对于不同截面型式的短柱试件进行了轴压试验。同时建立了有限元模型并与试验结果相验证,基于试验结果和有限元分析研究了试件的局部稳定。分析了现有直接强度法设计公式对于该类型截面柱的适用性。结果表明:直接强度法低估了腹板加颈肋的作用。     

冷弯薄壁U型钢轴压短柱承载力计算的直接强度法研究

现行北美冷弯型钢规范中直接强度法只适用于卷边C形、腹板加劲C形、Z形、R形和帽形这些截面形式较为简单的单肢截面,但并未涉及U形截面。为研究直接强度法对冷弯薄壁U型钢轴压短柱的适用性,采用ABAQUS非线性有限元分析了16种截面尺寸、4种厚度的64根试件,并对有限元模拟得到的极限承载力、部分学者试验结果进行回归,最终得到考虑U形截面屈曲后强度的局部屈曲承载力曲线。结果表明:现有的直接强度法公式计算结果偏于不安全,对现有的直接强度法公式进行了简单的修正,修正后的直接强度法计算式精度更高。     

冷弯薄壁卷边槽钢组合工字梁极限承载力计算的有效宽度法

为了研究冷弯薄壁卷边槽钢组合工字梁的受弯性能,对三种截面形式共计9根卷边槽钢组合工字梁进行破坏性试验研究,建立有限元分析方法对试件进行模拟分析,有限元计算结果与试验结果吻合良好,验证了有限元方法的正确性。接着采用有限元方法对冷弯薄壁卷边槽钢组合工字梁进行大量参数分析,钢种和受压翼缘宽厚比对受压翼缘有效宽厚比的影响较大,梁的长度、腹板高厚比与板件厚度对梁受压翼缘有效宽厚比的影响小。最后在对典型截面梁构件进行参数分析的基础上,得出卷边槽钢组合工字梁受压翼缘板件的有效宽厚比计算表格与计算公式,提出计算冷弯薄壁型钢梁极限承载力的有效宽度法,并通过试验验证了有效宽度法计算梁极限承载力的正确性和适用性。     

冷弯薄壁卷边槽钢轴压柱承载力的计算方法

对冷弯薄壁卷边槽钢轴压柱承栽力进行了稳定承载力计算,结果表明：直接强度法可以有效地预测冷弯薄壁卷边槽钢轴压柱的稳定承载力,与GB50018—2002中的有效宽度法计算结果和试验结果吻合良好且偏于安全。     

基于直接强度法的高强箱形轴压柱研究

采用直接强度法对高强箱形轴压柱的极限承载力进行计算,将计算结果与我国现行行业标准《低层冷弯薄壁型钢房屋建筑技术规程》（报批稿）计算结果进行比较,验证直接强度法公式的适用性.直接强度法计算中,利用有限条程序CUFSM计算截面的屈曲临界应力,分析组合柱的屈曲性能,并找出其翼缘宽厚比对柱子极限承载力的影响规律.     

等宽T型方管节点承载力计算

采用非线性有限元分析的方法和试验数据对等宽T型方管节点的试验方案、几何参数对其性能的影响进行了研究。在参数分析的基础上 ,采用回归的方法得出T型方管节点计算公式 ,公式计算结果与试验结果吻合良好。     

Load-carrying capacity of high-strength steel box-sections I: Stub columns

To study the load-carrying capacity of thin-walled box-section stub columns fabricated by high strength steel 18Mn2CrMoBA, uniaxial compression experiments of specimens with different geometrical dimensions were carried out. Compared with the predicted values by the AISI Code, the tested load-carrying capacities of the stub columns are much greater, which suggests that the existing effective width method should not be applicable for high strength steel stub columns. The finite element analysis based on ANSYS code was employed to simulate the deformation curves and predict the load-carrying capacities. The numerical values were generally in good agreement with the experimental values. Parameter analysis was performed to investigate the ultimate strength of the high strength steel stub column. The values obtained indicate that the width-thickness ratio of the flange and the section side ratio should be the main factors to decide the ultimate strength of the stub column. Taking the width-thickness ratio and the section side ratio as parameters, a formula to predict the loading capacity of the high strength steel stub column was put forward and proved to be effective by the tested and numerical values.     

内嵌CFRP板条加固RC梁抗剪承载力分析

分别对未加固和内嵌CFRP加固的钢筋混凝土梁建立了有限元模型,应用ANSYS软件进行非线性有限元分析,研究梁挠度和承载力,并与试验结果进行了比较,分析比较模拟结果和试验结果表明,所采用的有限元模型的合理性和有限元分析方法的正确性及CFRP加固钢筋混凝土梁可以显著提高其抗剪承载力。     

Cold-formed high strength stainless steel cross-sections in compression considering interaction effects of constituent plate elements

This paper presents a numerical investigation of cold-formed high strength stainless steel square and rectangular hollow sections in compression. A non-linear finite element model which includes geometric and material non-linearities was developed and verified against experimental results. The model was then used for an extensive parametric study to investigate the interaction effects of constituent plate elements on Class 3 slenderness limit and section capacities of cold-formed high strength stainless steel square and rectangular hollow sections in compression.The numerical investigation shows that the interaction effects of constituent plate elements on cross-section response are quite obvious particularly for slender sections. The design provisions on Class 3 slenderness limit and effective width equations specified in the EC3 Code and proposed by Gardner and Theofanous are suitable for square hollow sections, but not for rectangular hollow sections since they do not take into consideration of interaction effects of constituent plate element. Hence, the new Class 3 slenderness limit and the section capacity design equations based on the whole cross-section response are proposed in this study, which carefully consider the interaction effects of constituent plate elements.     

Design of cold-formed steel channels with stiffened webs subjected to bending

The objectives of this study are to investigate the structural behaviour and evaluate the appropriateness of the current direct strength method on the design of cold-formed steel stiffened cross-sections subjected to bending. The stiffeners were employed to the web of plain channel and lipped channel sections to improve the flexural strength of cold-formed steel sections that are prone to local buckling and distortional buckling. An experimental investigation of simply supported beams with different stiffened channel sections has been conducted. The moment capacities and observed failure modes at ultimate loads were reported. A nonlinear finite element model was developed and verified against the test results in terms of strengths, failure modes and moment–curvature curves. The calibrated model was then adopted for an extensive parametric study to investigate the moment capacities and buckling modes of cold-formed steel beams with various geometries of stiffened sections. The strengths and failure modes of specimens obtained from experimental and numerical results were compared with design strengths predicted using the direct strength method specified in the North American Specification for cold-formed steel structures. The comparison shows that the design strengths predicted by the current direct strength method (DSM) are conservative for both local buckling and distortional buckling in this study. Hence, the DSM is modified to cover the new stiffened channel sections investigated in this study. A reliability analysis was also performed to assess the current and modified DSM.     

Elastic stability analysis of cold-formed pallet rack structures with semi-rigid connections

This paper describe the three dimensional finite element modeling and elastic buckling analysis of single 2-D and 3-D frame (with semi-rigid connection) of conventional pallet racking system. Results from experimental study, effective length approach given by Rack Manufacturer's Institute (RMI) and finite element analysis of single 2-D frames of cold-formed steel pallet racking are compared. Finite element model used for single 2-D frame is further extended for 3-D frames with semi- rigid connection and results of these 3-D frames are also presented in the paper. Finite element analysis carried out on conventional pallet racks using the finite element program ANSYS with the 18 types of developed column sections. The principal aims were to find out the linear buckling load of single 2-D frames and to ascertain stability of 3-D frames of conventional pallet racking systems, made up of cold-formed sections with semi-rigid connection. Investigation into stability analysis of frames used in pallet rack structures by both experimental and finite element methods have shown that stiffening of the open upright sections using the spacer bar, channel and hat as external stiffeners will considerably increase the load carrying capacity of the frames.     

金属蒙皮板剪切性能的试验及有限元分析

结合蒙皮板在实际工程的做法,对压型钢板采用自攻螺丝连接的受力蒙皮进行剪切性能试验。通过对蒙皮的破坏模式和极限抗剪承载力的分析,对板型、檩条间距对蒙皮抗剪性能的影响进行研究。并采用ANSYS对蒙皮板进行有限元分析,考虑几何大变形、连接件的滑移等非线性因素。将试验数据与有限元结果进行比较,研究结果表明,采用ANSYS分析受力蒙皮是可行的,可以用有限元方法来代替大量重复性试验。     

受弯混凝土箱梁翼缘有效宽度试验研究与分析

在大比例长悬臂梯形截面混凝土箱梁模型受弯性能试验研究的基础上,结合混凝土箱梁的特点,通过选用相应的单元类型和材料本构关系,运用ANSYS大型有限元分析程序模拟了试验全过程,模拟结果与试验结果吻合较好;大量参数分析表明：在弹性受力范围内,宽跨比是影响翼缘有效宽度计算系数的主要因素;在承载力极限状态下,影响翼缘有效宽度计算系数的主要因素有宽跨比、纵向受拉区钢筋配筋率、钢筋屈服强度以及混凝土抗压强度。分别给出了翼缘有效宽度计算系数在弹性工作状态下和承载力极限状态下的计算公式,为初等梁理论应用于解决混凝土箱梁正截面受弯承载力计算提供了试验和理论依据。     

Ultimate capacity of battened columns composed of four equal slender angles

Cold-formed steel structural members play a great role in modern steel structures due to their high strength and light weight. The behavior and strength of battened column members composed of slender angle sections are mainly governed by local buckling of angle legs or torsional buckling of the angle between batten plates. Moreover, local buckling depends on the interaction between the width–thickness ratio of angle leg, overall slenderness ratio of angle between batten plates and overall slenderness of column. Theoretical study has been carried out by a nonlinear material and geometrical finite element model. Numerous cases of slender battened column sections having different width–thickness angle leg ratios, overall slenderness ratios between batten plates and overall slenderness ratios are chosen in this study. Complete ultimate strength curves are drawn and different failure modes are studied by taking different member lengths, which produce local or torsional buckling of single angles between batten plates or overall buckling of the member. Empirical equations for the effect of shear deformation factor and the ultimate axial load capacities of members formed of battened slender angle sections are proposed. Strengths of axially loaded battened members predicted using finite element as well as the proposed empirical equations is compared with the design strengths obtained using North American and European codes. It is concluded that the design strengths predicted by North American and European codes are generally conservative, and these design rules have been shown to be reliable using reliability analysis.