高强钢S460和S690火灾后力学性能试验
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摘要
火灾后,材料力学性能的退化是导致钢结构火灾后承载力降低的主要因素.通过试验研究高强钢S460和S690过火冷却至常温后的力学性能,得到过火高温对高强钢S460和S690的弹性模量、屈服强度、极限强度及应力-应变曲线的影响规律,并与普通钢火灾后力学性能进行对比.结果表明,当过火温度低于600℃时,S460和S690冷却后可恢复其基本力学性能;当过火温度超过600℃后,甚至高达1 000℃时,高强钢S460仍可恢复其常温下75%以上的力学性能,而S690仅可恢复其常温下64.5%的弹性模量、38.1%的屈服强度及57.3%的极限强度;高强钢火灾后力学性能与普通钢不同.通过对试验数据进行数值拟合,给出可准确表达S460和S690火灾后力学性能剩余程度的预测公式,可用于指导含高强钢S460和S690构件的钢结构火灾后检测与鉴定,并为相关规范的修订提供参考依据.
The load bearing capacity of steel structures after fire reduces mainly due to the deterioration of its mechanical properties. This paper presented an experimental study on material properties of high strength steels S460 and S690 after fire. The post-fire elastic modulus,yield and ultimate strengths,ductility and stress-strain curves were obtained and compared with the post-fire mechanical properties of mild strength steels. It is found that when the fire temperature from which the high strength steel is cooled down is less than or equal to 600 ℃,S460 and S690 can regain their original mechanical properties. When the fire temperature is up 1 000 ℃,S460 can also regain more than75% of its original mechanical properties,but S690 only regains 64.5% of its original elastic modulus,38.1% of its original yield strength and 57.3% of its original ultimate strength. The mechanical properties of high strength steels are different from mild strength steels. Predictive equations were proposed to evaluate the post-fire material properties of S460 and S690. Comparing with the test results,the predictive equations were validated. The predictive equations can be employed for practical inspection and appraisal of steel structures after fire with members made of S460 and S690,and provide a reference for the revision of current worldwide leading design standards.
The load bearing capacity of steel structures after fire reduces mainly due to the deterioration of its mechanical properties. This paper presented an experimental study on material properties of high strength steels S460 and S690 after fire. The post-fire elastic modulus,yield and ultimate strengths,ductility and stress-strain curves were obtained and compared with the post-fire mechanical properties of mild strength steels. It is found that when the fire temperature from which the high strength steel is cooled down is less than or equal to 600 ℃,S460 and S690 can regain their original mechanical properties. When the fire temperature is up 1 000 ℃,S460 can also regain more than75% of its original mechanical properties,but S690 only regains 64.5% of its original elastic modulus,38.1% of its original yield strength and 57.3% of its original ultimate strength. The mechanical properties of high strength steels are different from mild strength steels. Predictive equations were proposed to evaluate the post-fire material properties of S460 and S690. Comparing with the test results,the predictive equations were validated. The predictive equations can be employed for practical inspection and appraisal of steel structures after fire with members made of S460 and S690,and provide a reference for the revision of current worldwide leading design standards.
引文
[1]European Committee for Standardization.EN 1993-1-2,Eurocode3-design of steel structures-part 1-2:General rules-structural fire design[S].CEN,Brussels,2005.
[2]Australia Standards(AS).AS 4100:1998,Steel structures[S].Sydney,Australia,1998.
[3]Hong Kong Buildings Department.Code of practice for the structural use of steel[S].Hong Kong:The Government of the Hong Kong Special Administrative Region,2005.
[4]钢分类:GB/T 13304—2008[S].北京:中国标准出版社,2008.Steels Classification:GB/T 13304—2008[S].Beijing:Standards Press of China,2008.
[5]KODUR V,DWAIKAT M,FIKE R.High-temperature properties of steel for fire resistance modeling of structures[J].J Mater Civ Eng,2010,22:423-434.
[6]OUTINEN J,KESTI J,MAKELAINEN P.Fire design model for structural steel S355 based upon transient state tensile test results[J].J Constr Steel Res,1997,42:161-169.
[7]MAKELAINEN P,OUTINEN J,KESTI J.Fire design model for structure steel S420M based upon transient-state tensile test results[J].J Constr Steel Res,1998,48:47-57.
[8]OUTINEN J,KAITILA O,MAKELAINEN P.High-temperature testing of structural steel and modelling of structures at fire temperatures[R].Helsinki,Finland:Helsinki Univ of Technology Laboratory of Steel Structures,2001.
[9]OUTINEN J.Mechanical properties of structural steels at high temperatures and after cooling down,laboratory of steel structures[R].Helsinki,Finland:Helsinki Univ of Technology,2007.
[10]OUTINEN J,MAKELAINEN P.Mechanical properties of structural steel at elevated temperatures and after cooling down[J].Fire Mater,2004,28:237-251.
[11]LANGE J,WOHLFEIL N.Examination of the mechanical properties of the microalloyed grain refined steel S460 at elevated temperatures[J].Bautechnik,2007,84:711-720.
[12]SCHNEIDER R,LANGE J.Constitutive equations of structural steel S460 at high temperatures[C]//Nordic Steel Construction Conference 2009.Sweden,2009:204-211.
[13]SCHNEIDER R,LANGE J.Constitutive equations and empirical creep law of structural steel S460 at high temperatures[C]//Structures in Fire 2010.East Lansing:DEStech Publication Inc,2010:703-710.
[14]SCHNEIDER R,LANGE J.Material and creep behavior of S460 in case of fire experimental investigation and analytical modeling[C]//International Conference Application of Structural Fire Engineering.Prague:Cost,2011:55-60.
[15]YOUNG B,CHEN J,UY B.Behavior of high strength structural steel at evaluated temperatures[J].J Struct Eng ASCE,2006,132:1948-1954.
[16]陈建锋,曹平周.高温后结构钢力学性能试验[J].解放军理工大学学报,2010,11(3):328-333.CHEN Jianfeng,CAO Pingzhou.Experimental investigation into mechanical properties of steel post high temperatures[J].Journal of PLA University of Science and Technology,2010,11(3):328.
[17]丁发兴,余志武,温海林.高温后Q235钢材力学性能试验研究[J].建筑材料学报,2006,9(2):245-249.DING Faxing,YU Zhiwu,WEN Hailin.Experimental research on mechanical properties of Q235 steel after high temperature treatment[J].Journal of Building Materials,2006,9(2):245.
[18]张有桔,朱跃,赵升,等.高温后不同冷却条件下钢材力学性能试验研究[J].结构工程师,2009,25(5):104-109.ZHANG Youjie,ZHU Yue,ZHAO Sheng,et al.Experimental research on mechanial properties of steel cooled in different modes after high temperature treatment[J].Structural Engineers,2009,25(5):104.
[19]British Standards Institution(BSI).BS 5950-8,Structural use of steelwork in building-part 8:Code of practice for fire resistant design[S].London,1998.
[20]European standard EN 10025-3.Hot rolled products of structural steelspart3:Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels[S].CEN,Brussels,2004.
[21]European standard EN 10025-6.Hot rolled products of structural steels-part6:technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition[S].CEN,Brussels,2009.
[22]European standard EN 10002-5.Metallic materials tensile testing-part5:Method of testing at elevated temperature[S].Brussels,1992.
[23]ASTM E21-09.Standard test methods for elevated temperature tension tests of metallic materials[S].West Conshohocken,United States,2009.
[2]Australia Standards(AS).AS 4100:1998,Steel structures[S].Sydney,Australia,1998.
[3]Hong Kong Buildings Department.Code of practice for the structural use of steel[S].Hong Kong:The Government of the Hong Kong Special Administrative Region,2005.
[4]钢分类:GB/T 13304—2008[S].北京:中国标准出版社,2008.Steels Classification:GB/T 13304—2008[S].Beijing:Standards Press of China,2008.
[5]KODUR V,DWAIKAT M,FIKE R.High-temperature properties of steel for fire resistance modeling of structures[J].J Mater Civ Eng,2010,22:423-434.
[6]OUTINEN J,KESTI J,MAKELAINEN P.Fire design model for structural steel S355 based upon transient state tensile test results[J].J Constr Steel Res,1997,42:161-169.
[7]MAKELAINEN P,OUTINEN J,KESTI J.Fire design model for structure steel S420M based upon transient-state tensile test results[J].J Constr Steel Res,1998,48:47-57.
[8]OUTINEN J,KAITILA O,MAKELAINEN P.High-temperature testing of structural steel and modelling of structures at fire temperatures[R].Helsinki,Finland:Helsinki Univ of Technology Laboratory of Steel Structures,2001.
[9]OUTINEN J.Mechanical properties of structural steels at high temperatures and after cooling down,laboratory of steel structures[R].Helsinki,Finland:Helsinki Univ of Technology,2007.
[10]OUTINEN J,MAKELAINEN P.Mechanical properties of structural steel at elevated temperatures and after cooling down[J].Fire Mater,2004,28:237-251.
[11]LANGE J,WOHLFEIL N.Examination of the mechanical properties of the microalloyed grain refined steel S460 at elevated temperatures[J].Bautechnik,2007,84:711-720.
[12]SCHNEIDER R,LANGE J.Constitutive equations of structural steel S460 at high temperatures[C]//Nordic Steel Construction Conference 2009.Sweden,2009:204-211.
[13]SCHNEIDER R,LANGE J.Constitutive equations and empirical creep law of structural steel S460 at high temperatures[C]//Structures in Fire 2010.East Lansing:DEStech Publication Inc,2010:703-710.
[14]SCHNEIDER R,LANGE J.Material and creep behavior of S460 in case of fire experimental investigation and analytical modeling[C]//International Conference Application of Structural Fire Engineering.Prague:Cost,2011:55-60.
[15]YOUNG B,CHEN J,UY B.Behavior of high strength structural steel at evaluated temperatures[J].J Struct Eng ASCE,2006,132:1948-1954.
[16]陈建锋,曹平周.高温后结构钢力学性能试验[J].解放军理工大学学报,2010,11(3):328-333.CHEN Jianfeng,CAO Pingzhou.Experimental investigation into mechanical properties of steel post high temperatures[J].Journal of PLA University of Science and Technology,2010,11(3):328.
[17]丁发兴,余志武,温海林.高温后Q235钢材力学性能试验研究[J].建筑材料学报,2006,9(2):245-249.DING Faxing,YU Zhiwu,WEN Hailin.Experimental research on mechanical properties of Q235 steel after high temperature treatment[J].Journal of Building Materials,2006,9(2):245.
[18]张有桔,朱跃,赵升,等.高温后不同冷却条件下钢材力学性能试验研究[J].结构工程师,2009,25(5):104-109.ZHANG Youjie,ZHU Yue,ZHAO Sheng,et al.Experimental research on mechanial properties of steel cooled in different modes after high temperature treatment[J].Structural Engineers,2009,25(5):104.
[19]British Standards Institution(BSI).BS 5950-8,Structural use of steelwork in building-part 8:Code of practice for fire resistant design[S].London,1998.
[20]European standard EN 10025-3.Hot rolled products of structural steelspart3:Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels[S].CEN,Brussels,2004.
[21]European standard EN 10025-6.Hot rolled products of structural steels-part6:technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition[S].CEN,Brussels,2009.
[22]European standard EN 10002-5.Metallic materials tensile testing-part5:Method of testing at elevated temperature[S].Brussels,1992.
[23]ASTM E21-09.Standard test methods for elevated temperature tension tests of metallic materials[S].West Conshohocken,United States,2009.