冷弯薄壁卷边槽钢檩条弯曲变形的抗弯刚度

在分析比较欧洲规范EN 1993-1-3和我国《冷弯薄壁型钢结构技术规范》(GB 50018—2002)的基础上,针对冷弯薄壁卷边槽钢檩条弯曲变形的抗弯刚度进行了较深入的探讨和对比分析。计算结果表明:按《冷弯薄壁型钢结构技术规范》(GB 50018—2002)计算有效截面抗弯刚度相对保守,按毛截面计算抗弯刚度稍显不安全,按EN 1993-1-3计算相对合理。在满应力状况下,对于2mm厚C140~C250规格的冷弯薄壁卷边槽钢檩条,在正常使用极限状态下,抗弯刚度折减系数可取毛截面抗弯刚度的0.95倍(Q235钢)和0.9倍(Q345钢)。     

卷边槽钢纯弯构件畸变屈曲板组约束系数的直接强度法分析

现行国家规范《冷弯薄壁型钢结构技术规范》(GB50018-2002)提出适用于各种型钢构件板组的约束系数统一计算公式。针对冷弯薄壁卷边槽钢纯弯构件畸变屈曲运用直接强度法计算受压翼缘板组约束系数,并与GB 50018-2002计算结果比较,得到一些有价值的结论,供设计研究参考。     

用我国规范计算高强度冷弯薄壁型钢柱的适用性

将《冷弯薄壁型钢结构技术规范》(GB 50018-2002),用于计算比Q345钢强度更高的钢材制成的冷弯薄壁非卷边等边角钢和槽钢柱。对计算结果与试验、有限元分析结果及国外规范计算结果进行比较发现,对两端固支的槽钢和宽厚比大于25的等边角钢,计算偏于安全,对宽厚比小于25的等边角钢和两端铰支槽钢的安全性有待研究。提出采用多条柱子曲线以适应不同截面、不同壁厚、不同强度的高强度冷弯薄壁型钢柱。     

卷边槽钢纯弯构件畸变屈曲板组约束系数的直接强度法分析

现行国家规范《冷弯薄壁型钢结构技术规范》(GB50018-2002)提出适用于各种型钢构件板组的约束系数统一计算公式。本文针对冷弯薄壁卷边槽钢纯弯构件畸变屈曲运用直接强度法计算受压翼缘板组约束系数,并与GB50018-2002计算结果比较,得到一些有价值的结论,供设计研究参考。     

冷弯薄壁卷边槽钢檩条的有效截面分析

在分析比较Eurocode 3(EN 1993-1-3)和GB 50018—2002《冷弯薄壁型钢结构技术规范》的基础上,针对冷弯薄壁卷边槽钢檩条的有效截面进行探讨和对比分析。计算结果表明:GB 50018—2002计算有效截面模量相对保守,按Eurocode 3(EN 1993-1-3)计算相对合理。在满应力状况下,对于采用2 mm厚C180—C250规格的冷弯薄壁卷边槽钢檩条,有效截面模量的折减系数分别可取为0.9(Q235钢材)和0.8(Q345钢材)。     

Q235冷弯薄壁卷边槽钢梁承载力计算方法

在分析比较GB 50018—2002冷弯薄壁型钢结构技术规范和GB 51022—2015门式刚架轻型房屋钢结构技术规范的基础上,对卷边槽钢梁极限受弯承载力计算方法进行了探讨和比对分析。计算结果表明:按GB 50018—2002冷弯薄壁型钢结构技术规范计算冷弯薄壁卷边槽钢梁是可行的,经试验验证,偏于安全。     

用我国规范计算高强冷弯薄壁卷边槽钢柱的适用性

在分析比较冷弯薄壁型钢结构技术规范(GB 50018-2002)、欧洲规范Eurocode3(EN1993一1-3)和北美规范(AISI S100一2007)的基础上,结合已有试验结果,针对比Q345钢强度更高的钢材制成的冷弯薄壁卷边槽钢柱的极限承载力进行了较深入的探讨和对比分析。结果表明:按冷弯薄壁型钢结构技术规范(GB5001 8一2002)计算两端固支槽钢柱是可行的。     

中美规范关于卷边槽形受弯构件承载力比较分析

新近纳入北美规范NAS 2004的直接强度法对冷弯型钢构件的畸变屈曲要求单独验算,但《冷弯薄壁型钢结构技术规范》(GB 50018-2002)对此还无明确规定。在总结冷弯型钢构件畸变屈曲性能的基础上,对其承载力计算方法给予介绍,由简化模型计算得到的受弯构件的畸变屈曲弹性临界应力中,引入直接强度法计算“规范”(GB 50018-2002)附录中卷边槽形受弯构件的承载力。结果表明,附录中部分截面的受弯承载力由畸变屈曲控制。同时,NAS 2004与“规范”(GB 50018-2002)计算结果的比较表明,“规范”(GB 50018-2002)的计算规定虽安全,但太过保守。因此,提出将翼缘屈曲系数调高至3.0的建议。     

Q235冷弯薄壁等边角钢压杆承载力计算方法

在分析比较GB 50018—2002冷弯薄壁型钢结构技术规范条文规定的基础上,结合试验结果,对Q235冷弯薄壁等边角钢压杆承载力计算方法进行了较深入的探讨和分析比对,研究结果显示:采用有效宽度法的国内现行规范GB 50018—2002可以有效地预测Q235冷弯薄壁等边角钢压杆的稳定承载力,与试验结果吻合良好且偏于安全。     

采用GB 50018—2002计算壁厚小于2 mm的受弯构件承载力的适用性分析

对各国已有的壁厚小于2 mm的冷弯薄壁型钢梁受弯性能试验中的86根槽形、40根Z形、6根帽形和6根工字形冷弯薄壁型钢梁的试验资料进行总结。采用中国《冷弯薄壁型钢结构技术规范》（GB 50018—2002）第5.3节中受弯构件的相关规定计算各构件的极限弯矩,将计算结果与试验结果进行比较。结果表明:按中国规范GB 50018—2002规定计算壁厚小于2 mm的冷弯薄壁型钢受弯构件承载力是可行的,试验值均大于规范理论计算值,规范理论计算值偏于安全。     

Column tests of cold-formed steel non-symmetric lipped angle sections

The geometry of angle sections is simple, but the behaviour and design calculations of angle sections can be quite complicated. Furthermore, lipped angle sections with unequal flange widths form a non-symmetric section and the behaviour of the section is even more complicated than a singly-symmetric angle section with equal flange widths. A test program on cold-formed steel non-symmetric lipped angle columns is presented. The non-symmetric angle sections were brake-pressed from high strength structural steel sheets having nominal yield stresses of 450 and 550 MPa with plate thicknesses of 1.0, 1.5 and 1.9 mm. The material properties of the column specimens were obtained by tensile coupon tests. The behaviour and strengths of cold-formed steel non-symmetric lipped angle columns were investigated. The test strengths are compared with the design strengths calculated using the North American Specification for the design of cold-formed steel structural members. In addition, the current design rules in the North American Specification for cold-formed steel non-symmetric lipped angle columns are assessed using reliability analysis. It is shown that the design strengths are generally quite conservative.     

绕弱轴纯弯的冷弯薄壁型钢构件畸变屈曲性能研究

采用有限条软件CUFSM对不同截面几何参数的冷弯薄壁卷边槽钢绕弱轴纯弯进行畸变屈曲应力计算,并根据经典板件屈曲应力公式计算构件翼缘畸变屈曲系数,分析构件截面几何参数的变化对畸变屈曲系数的影响,在此基础上,提出适用于求解直卷边槽钢绕弱轴纯弯畸变屈曲应力的简化公式。与有限条法和基于广义梁理论的横向弯曲铰支计算模型的计算公式进行对比,所提出的公式具有较高精度,且简单实用、便于手算,建议公式可供工程设计和修订规范参考。     

冷弯型钢受压构件的LRFD抗力系数

目前,冷弯型钢抗压构件的LRFD抗力系数取值为0.85,该文旨在研究该系数能否增大。数据库中包含675组同中心荷载柱的试验数据,包含平口卷边C截面、平口卷边Z截面、帽形截面和角形截面以及开孔构件。采用美国钢铁协会标准和直接强度法计算每个试样的强度。直接强度法的计算结果更加精确,其在计算部分有效截面柱的强度时尤为精确。采用一阶二次矩法计算的LRFD抗力系数,与美国钢铁协会标准和直接强度法的规定相符。对于柱的两种破坏情况,达到畸变屈曲极限状态而破坏和由于整体失稳或局部-整体失稳相互作用而破坏,前者的计算结果更为精确。单角钢柱的试验强度与计算强度的比值有很大变化,随着整体长细比的增加,计算结果逐渐变得极为保守。     

Performance of CFTST column to steel beam joints with blind bolts under cyclic loading

The objective of this research is to investigate the seismic performance of the composite joint consisting of square concrete filled thin-walled steel tubular (CFTST) column and steel beam with end plate and blind bolts. The cold-formed square tube in each CFTST column connection was fabricated by seam welding together four pieces of lipped angle with nominal wall thickness 1.5 mm or 3 mm. Four exterior joint specimens were tested under axially compressive load on the top of the columns and cyclic loads on the beam tip. The experimental parameters in the study were the thickness of the steel tube and the type of end plate. The seismic response of the blind bolted moment joints to CFTST columns was analyzed and evaluated in terms of the hysteretic behavior, failure modes, stiffness and strength degradation, ductility, and energy dissipation capacities of the joints. To improve the tension behavior of the blind bolted moment connections to the thin tube wall, the anchorage action of reinforcing rebar welded to the bolts with concrete-filled steel tubes was also investigated to consider the effect of cyclic loading. The experimental and analytical results indicated that when the end plate thickness is not less than 3 mm, the flush or extended end plate joints to CFTST columns exhibited large hysteretic loops and excellent seismic performance, such as ductility and energy dissipation capacity. The proposed innovative blind bolted joint was verified as a reliable and effective solution applied in mid- and low-rise buildings through properly design and detailing.     

高强冷弯薄壁型钢卷边槽形截面轴压构件试验研究及承载力分析

对63根屈服强度550MPa高强冷弯薄壁型钢卷边槽形截面轴压构件进行试验研究,分析了构件的屈曲模式和极限承载力,并将参考AISI规范、澳洲规范和北美规范及我国现行行业标准《低层冷弯薄壁型钢房屋建筑技术规程》（报批稿）计算的构件承载力与试验结果进行分析比较。在此基础上,对高强超薄壁型钢卷边槽形截面轴压构件的承载力合理计算模式进行研究。结果表明：高强超薄壁型钢卷边槽形截面轴压构件在宽厚比较大时会出现畸变屈曲模式;采用等效板件方法计算加劲板件有效宽度后,我国《低层冷弯薄壁型钢房屋建筑技术规程》（报批稿）适用于屈曲强度550MPa、厚度小于2.00mm的冷弯薄壁型钢卷边槽形截面构件承载力计算。     

边缘加劲板件有效宽厚比设计方法中的板组效应研究

本文根据能量原理,建立了边缘加劲板件的弹性屈曲理论和卷边槽形截面薄壁构件的板组相关屈曲理论。通过屈曲理论分析,得到了非均匀受压边缘加劲板件的屈曲系数及其反映板组效应的约束系数,并将其引入新修订的《冷弯薄壁型钢结构技术规范》(GB50018)的有效宽厚比设计方法中。本文介绍了50根冷弯薄壁型钢受压构件试验,并按修订后的规范方法进行了试件承载力计算,计算值与试验值比较,偏于安全。将考虑板组效应的有效宽厚比设计方法与国内外现行规范设计方法相比较,具有优越性。     

Compression tests on cold-formed steel columns with monosymmetrical section

This paper presents the results of an experimental study on cold-formed steel columns made at the Building Research Institute of Timisoara. The specimens were press-braked and their thickness ranged from 2 to 4 mm. Channel sections and lipped channel sections were tested, including columns and stub columns tests.

Theoretical ultimate capacities were determined by bdAISI, ECCS and Eurocode 3—Annex A specifications. Differences between designed and experimental values for these three methods are insignificant, and theoretical results are confirmed by experimental tests for stub columns. For columns, good agreement with theoretical predictions is obtained by applying the reduction coefficients for ultimate loads given in specifications. Both for columns and stub columns, the results are more conservative for channel than for lipped channel sections.     

高强冷弯薄壁型钢轴压柱畸变屈曲研究

550MPa高强冷弯薄壁型钢卷边槽形截面轴压柱发生畸变屈曲时会出现三种模式（O—O,O-I,I—I）,考虑材料和几何双重非线性的有限元法对三种畸变屈曲模式的构件承载力、变形模式、畸变屈曲应力、横截面应力的分布等相关性能进行比较分析,可看出三种畸变屈曲模式诸性能存在较大不同,同时畸变屈曲与局部屈曲、整体屈曲在相关性能方面也存在不同。采用直接强度法对畸变屈曲轴压柱极限承载力进行计算,计算结果与试验结果较吻合,故在计算畸变屈曲轴压柱极限承载力时建议采用直接强度法．