冷弯薄壁型钢受弯构件截面弹性局部屈曲试验与理论研究
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摘要
目前，对于冷弯薄壁型钢构件，国内外普遍应用有效截面设计法，该方法单独考虑各个板件的局部屈曲，忽略或简单考虑了板组之间的相关作用，对于有复杂加劲的高强冷弯薄壁型钢很难确定板的有效宽度。此外，有效宽度与板的应力梯度有关，精确计算须迭代，设计效率很低。近十多年，美国康奈尔大学T.Pekoz、B.Schafer和澳大利亚G.Hancock等研究了一种不再用有效截面和其几何性质，而直接用构件的全截面和其几何性质的新方法—直接强度法。直接强度法求解构件的极限荷载建立在截面的弹性屈曲基础之上，其关键点在于求解截面的局部屈曲应力f_(ol)。
本文在已有弹性相关屈曲研究成果的基础上，对普通Q235钢和550MPa高强冷弯薄壁型钢帽形截面简支檩条在受弯状态下整个截面的弹性局部屈曲进行了试验，得出了截面弹性局部屈曲临界应力的试验值f_(ol)~l，以此验证了有限条程序CUFSM求解帽形截面檩条弹性局部屈曲的可行性。利用CUFSM分析了截面受压翼缘弹性局部屈曲应力系数k_f的影响因素，结果表明帽形截面翼缘与腹板宽度的比值b_2／b_1的影响最大。拟合了帽形截面檩条受压翼缘弹性局部屈曲系数k_f的近似计算公式，并通过对比分析验证了公式的可靠性。
At present, the Effective Width Method (EWM) is widely used to design cold-formed steel members at home and abroad. This approach only considers local buckling of individual element and neglects the interaction of the adjacent plates. The effective width of a plate is related to stress gradient, which makes the EWM considerately difficult especially for the sections with complex stiffeners. T.Pekoz B.Schafer(both come from Cornell University ) and G. Hancock (comes from Australia) develop a new method named Direct Strength Method (DSM) in the last ten years. This method doesn't use effective width. It uses gross section and its geometric properties. Direct Strength Method is based on the elastic local buckling of the section and its key point is to determine the local buckling stress f_(ol) of the section.
Based on the published materials of elastic interactive buckling, the experimental and theoretical study of critical elastic local buckling stress f_(ol) of the complete section of hat-shaped purlin made from Q235 and 550MPa high strength cold-formed steel have been completed. The experimental result confirmed that the finite strip method can be used to solve the critical elastic local buckling moment or stress. Several kinds of factor s that affect the critical elastic local buckling were analysed. Among these factors, the ratio of the web to the flange named b_2/b_1 is the major factor. A simplified formula for the elastic local interactive buckling coefficient K was presented.
本文在已有弹性相关屈曲研究成果的基础上，对普通Q235钢和550MPa高强冷弯薄壁型钢帽形截面简支檩条在受弯状态下整个截面的弹性局部屈曲进行了试验，得出了截面弹性局部屈曲临界应力的试验值f_(ol)~l，以此验证了有限条程序CUFSM求解帽形截面檩条弹性局部屈曲的可行性。利用CUFSM分析了截面受压翼缘弹性局部屈曲应力系数k_f的影响因素，结果表明帽形截面翼缘与腹板宽度的比值b_2／b_1的影响最大。拟合了帽形截面檩条受压翼缘弹性局部屈曲系数k_f的近似计算公式，并通过对比分析验证了公式的可靠性。
At present, the Effective Width Method (EWM) is widely used to design cold-formed steel members at home and abroad. This approach only considers local buckling of individual element and neglects the interaction of the adjacent plates. The effective width of a plate is related to stress gradient, which makes the EWM considerately difficult especially for the sections with complex stiffeners. T.Pekoz B.Schafer(both come from Cornell University ) and G. Hancock (comes from Australia) develop a new method named Direct Strength Method (DSM) in the last ten years. This method doesn't use effective width. It uses gross section and its geometric properties. Direct Strength Method is based on the elastic local buckling of the section and its key point is to determine the local buckling stress f_(ol) of the section.
Based on the published materials of elastic interactive buckling, the experimental and theoretical study of critical elastic local buckling stress f_(ol) of the complete section of hat-shaped purlin made from Q235 and 550MPa high strength cold-formed steel have been completed. The experimental result confirmed that the finite strip method can be used to solve the critical elastic local buckling moment or stress. Several kinds of factor s that affect the critical elastic local buckling were analysed. Among these factors, the ratio of the web to the flange named b_2/b_1 is the major factor. A simplified formula for the elastic local interactive buckling coefficient K was presented.
引文
[1] Schafer, B. W., Pekoz, T.. "Laterally Braced Cold-Formed Steel Flexural Members with Edge Stiffened Flanges." ASCE, Journal of Structural Engineering. 1999, 125 (2) 118-127.
[2] Hancock G. J., et al. Cold-Formed Steel Structures to the AISI Specification. Marcel Dekker, New York, 2001.
[3] Design of Cold-Formed Steel Structural Members using the Direct Strength Method, Appendix 1 of the North American Specification for the Design of Cold-Formed Members, 2004.
[4] 何保康，周天华．冷弯型钢截面局部屈曲和AISI规范计算有效宽度的统一法则．建筑钢结构进展，2005，7(4)．
[5] 蒋路．高强冷弯薄壁型钢轴压长柱试验与理论研究．西安建筑科技大学硕士学位论文．2005．
[6] American Iron and Steel Institute. 1996 Edition of the Specification for the Design of Cold-Formed Steel Structural Members. 1997, Washington, DC, USA.
[7] Allen H G, bulson P s. Background to Buckling. Maidenhead: McGraw-Hill, 1980.
[8] 陈骥．钢结构稳定理论与设计(第二版)．科学出版社，2003。
[9] 陈绍蕃．钢结构稳定设计指南．北京．中国建筑工业出版社．1996．
[10] Trahair N S, Braford M A. The Behavior and Design of Steel Structures. 2nd ed. London: Chapman and Hall, 1998.
[11] GB50018-2002．冷弯薄壁型钢结构技术规范．北京．中国计划出版社，2002．
[12] British Standards Institution. Structural Use of Steel Work in Building, Part 5, Code of Practice for Design of Cold Formed Section. 1987.
[13] 何保康，蒋路．冷弯薄壁型钢构件的直接强度法．建筑结构，2007．1．
[14] Commentary of Design of Cold-Formed Steel Structural Members using the Direct Strength Method, Appendix 1 of the NAS, 2004.
[15] Bleich，F．同济大学钢木结构教研室译．金属结构的屈曲强度(M)．北京科学出版社，1965。
[16] Timoshenko, S. P. and Gere, J. M., Theory of Elastical Stability, McGraw-Hill, New York, 1959.
[17] Desmond, T. P., Pekoz, T. and Winter, G., Edge Stiffeners for Thin-Walled Members. Journal of structural engineering, Vol. 107, No. ST2, 1981.
[18] Allen H. G. and Bulson P. S.: Background to Buckling[M], Maidenhead: McGraw-Hill, 1980.
[19] BS5950-1998 Structural Use Of Steelwork in Building-Part5. Code of Practice for Design of Cold-Formed Thin Gauge Sections
[20] Mulligan G. P. and Pekoz T.: Local Buckling Interaction Mulligan G. P. and Pekoz T.: Local Buckling Interaction in Cold-Formed Columns, Journal of Structural Engineering[J], Vol. 113, No. 3, March, 1987: 604-620
[21] Hancock. Local, Distortional and Lateral Buckling of I-Beams. J. of the Structural Div., Vol. 104, No. ST11, November, 1978, pp. 1787-1798.
[22] Cheung, Y. K., Finite Strip Method in Structural Analysis, Pergamon Press, Inc. New York, N. Y., 1976.
[23] Thin-wall V2.1, Cross-section Analysis and Finite Strip Analysis and Direct Strength Design of Thin-wall Structures, Center for Advanced Structural Engineering, University of Sydney, http://www.civil.usyd.edu.au/case/thinwall
[24] CUFSM v2.6, Elastic Buckling Analysis of Thin-Walled Members by Finite Strip Analysis. http://www.ce.jhu.edu/bshafer/cufsm.
[25] 陈绍蕃，惠颖：冷弯薄壁型钢局部屈曲的相关性和卷边板件的有效宽度，西安建筑科技大学学报[J]，Vol．27，No．1，1995年3月。
[26] 陈剑，顾强，陈绍蕃：薄壁卷边槽钢梁板件相关屈曲分析及受压翼缘的有效宽厚比(Ⅰ)，西安建筑科技大学学报[J]，1996，28(1)：14-18。
[27] 陈剑，顾强，陈绍蕃：薄壁卷边槽钢梁板件相关屈曲分析及受压翼缘的有效宽厚比(Ⅱ)，西安建筑科技大学学报[J]，1996，28(4)：383-387。
[28] 周绪红，莫涛，周期石：部分加劲板件有效宽厚比设计方法中的板组效应，全国轻型钢结构标准技术委员会2002年会暨学术交流会论文集(补充部分)，武汉，2000：1-13。
[29] 陈绍蕃：冷弯型钢板件相关屈曲的极限承载力，建筑钢结构进展[J]，Vol．4，No．1，2002年。
[30] 陈绍蕃．钢结构设计原理(第三版)．科学出版社，2005。
[2] Hancock G. J., et al. Cold-Formed Steel Structures to the AISI Specification. Marcel Dekker, New York, 2001.
[3] Design of Cold-Formed Steel Structural Members using the Direct Strength Method, Appendix 1 of the North American Specification for the Design of Cold-Formed Members, 2004.
[4] 何保康，周天华．冷弯型钢截面局部屈曲和AISI规范计算有效宽度的统一法则．建筑钢结构进展，2005，7(4)．
[5] 蒋路．高强冷弯薄壁型钢轴压长柱试验与理论研究．西安建筑科技大学硕士学位论文．2005．
[6] American Iron and Steel Institute. 1996 Edition of the Specification for the Design of Cold-Formed Steel Structural Members. 1997, Washington, DC, USA.
[7] Allen H G, bulson P s. Background to Buckling. Maidenhead: McGraw-Hill, 1980.
[8] 陈骥．钢结构稳定理论与设计(第二版)．科学出版社，2003。
[9] 陈绍蕃．钢结构稳定设计指南．北京．中国建筑工业出版社．1996．
[10] Trahair N S, Braford M A. The Behavior and Design of Steel Structures. 2nd ed. London: Chapman and Hall, 1998.
[11] GB50018-2002．冷弯薄壁型钢结构技术规范．北京．中国计划出版社，2002．
[12] British Standards Institution. Structural Use of Steel Work in Building, Part 5, Code of Practice for Design of Cold Formed Section. 1987.
[13] 何保康，蒋路．冷弯薄壁型钢构件的直接强度法．建筑结构，2007．1．
[14] Commentary of Design of Cold-Formed Steel Structural Members using the Direct Strength Method, Appendix 1 of the NAS, 2004.
[15] Bleich，F．同济大学钢木结构教研室译．金属结构的屈曲强度(M)．北京科学出版社，1965。
[16] Timoshenko, S. P. and Gere, J. M., Theory of Elastical Stability, McGraw-Hill, New York, 1959.
[17] Desmond, T. P., Pekoz, T. and Winter, G., Edge Stiffeners for Thin-Walled Members. Journal of structural engineering, Vol. 107, No. ST2, 1981.
[18] Allen H. G. and Bulson P. S.: Background to Buckling[M], Maidenhead: McGraw-Hill, 1980.
[19] BS5950-1998 Structural Use Of Steelwork in Building-Part5. Code of Practice for Design of Cold-Formed Thin Gauge Sections
[20] Mulligan G. P. and Pekoz T.: Local Buckling Interaction Mulligan G. P. and Pekoz T.: Local Buckling Interaction in Cold-Formed Columns, Journal of Structural Engineering[J], Vol. 113, No. 3, March, 1987: 604-620
[21] Hancock. Local, Distortional and Lateral Buckling of I-Beams. J. of the Structural Div., Vol. 104, No. ST11, November, 1978, pp. 1787-1798.
[22] Cheung, Y. K., Finite Strip Method in Structural Analysis, Pergamon Press, Inc. New York, N. Y., 1976.
[23] Thin-wall V2.1, Cross-section Analysis and Finite Strip Analysis and Direct Strength Design of Thin-wall Structures, Center for Advanced Structural Engineering, University of Sydney, http://www.civil.usyd.edu.au/case/thinwall
[24] CUFSM v2.6, Elastic Buckling Analysis of Thin-Walled Members by Finite Strip Analysis. http://www.ce.jhu.edu/bshafer/cufsm.
[25] 陈绍蕃，惠颖：冷弯薄壁型钢局部屈曲的相关性和卷边板件的有效宽度，西安建筑科技大学学报[J]，Vol．27，No．1，1995年3月。
[26] 陈剑，顾强，陈绍蕃：薄壁卷边槽钢梁板件相关屈曲分析及受压翼缘的有效宽厚比(Ⅰ)，西安建筑科技大学学报[J]，1996，28(1)：14-18。
[27] 陈剑，顾强，陈绍蕃：薄壁卷边槽钢梁板件相关屈曲分析及受压翼缘的有效宽厚比(Ⅱ)，西安建筑科技大学学报[J]，1996，28(4)：383-387。
[28] 周绪红，莫涛，周期石：部分加劲板件有效宽厚比设计方法中的板组效应，全国轻型钢结构标准技术委员会2002年会暨学术交流会论文集(补充部分)，武汉，2000：1-13。
[29] 陈绍蕃：冷弯型钢板件相关屈曲的极限承载力，建筑钢结构进展[J]，Vol．4，No．1，2002年。
[30] 陈绍蕃．钢结构设计原理(第三版)．科学出版社，2005。