International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 06 | Jun 2025 www.irjet.net p-ISSN: 2395-0072
Cold-Formed High Strength Steel Columns: A Comprehensive Review of Structural Performance and Design Approaches
Saumiyaa K S1 , Amali D2
1Post Graduate Student, Department of Civil Engineering, Government College of Engineering, Salem – 636 011, Tamil Nadu, India
2Assistant Professor, Department of Civil Engineering, Government College of Engineering, Salem – 636 011, Tamil Nadu, India ***
Abstract - Thisliteraturereviewanalyzestenstudiesonthe structuralbehavior of highstrengthsteel tubular and welded sectionsundercompression,bending,andpost-fireconditions. The research highlights that current design codes are generally conservative for compact sections but often inaccurate for slender or fire-exposed members. Improved methods such as the Continuous Strength Method and modifiedDirectStrengthMethodhaveshownbetteraccuracy inpredictingstructuralperformance.Post-firestudiesfurther reveal that some design standards overestimate residual strength, especially for slender columns. Overall, the review emphasizes the need to refine existing design approaches to match the behavior of modern high strength steels and support the development of more reliable and efficient structural design practices.
Key Words: Axial Compression, Cold-formed steel, Design codes, Finite Element Analysis, High strength steel, Post fire behavior, Structural Performance
1.INTRODUCTION
Cold-formed steel (CFS) is a versatile and increasinglypopularmaterial inmodernconstructionand manufacturing. Unlike hot-rolled steel, which is shaped at hightemperatures,CFSundergoesa"cold-working"process, typicallyroll-formingorpress-braking,atroomtemperature. This cold-working fundamentally alters the steel's mechanicalproperties.
High-strength cold-formed steel is produced by shapingsteel atroomtemperaturethroughprocesseslike roll-forming or press-braking. This "cold working" significantly increases its yield strength (by 15-50%) and tensilestrength,makingitmuchstrongerandmoredurable thanhot-rolledsteel,especiallyinthebentsections.
Its advantages include an excellent strength-toweight ratio, precise dimensional accuracy, and good corrosion resistance (often galvanized). These properties make it ideal for lightweight yet robust structures in residentialandcommercialconstruction,automotiveparts, andappliances,offeringbenefitslikereducedmaterialand laborcosts,fasterconstruction,andenhancedsafety.
2. LITERATURE REVIEW
2.1 Axial Compression Behavior
This paper [1], experimentally investigates stub columnsmadefromcold-formedhigh-strengthsteel(HSS) tubularsectionswithyieldstrengthsof700,900,and1,100 MPa.Atotalof25testsonSHS,RHS,andCHSsectionswere conductedtoevaluateaxialcapacity,materialproperties,and geometric imperfections. The results were compared with variousdesigncodes,revealingthatexistingstandardsare conservativeforcompactsectionsbutmayunderestimateor slightlyoverestimatestrengthforslenderones.
A validated finite element model was developed, accounting for cold-forming effects, imperfections, and residual stresses. The model closely matched the experimentaloutcomes.Thestudyalsosuggeststhatcurrent yield slenderness limits, especially for CHS, may be too conservativeforhigh-strengthsteels,recommendingrevised limitstobetterreflectactualperformance.
2.2 YSt–310 Stub Column Behavior
ThisstudyinvestigatesthestructuralperformanceofYSt–310cold-formedtubularsteelstubcolumns(SHSandRHS) usingbothexperimentsandfiniteelementanalysis.Material propertieswereevaluatedthroughmicrostructureanalysis, hardness tests, and tensile tests on flat, corner, and weld specimens.Resultsshowedenhancedstrengthincornerand weld regions due to cold-forming effects, though with reducedductility.
Authorsin[2]showthecarriedoutstubcolumntestsand calibrated FE models were used to assess compressive capacityandcomparedagainstEC3,DSM,CSM,andmodified DSMdesignmethods.Thestudyfoundexistingcodestobe conservativeforslendersections,whilethemodifiedDSM gavemore accurate predictions.Design recommendations wereproposedtobettersuitYSt–310cold-formedsteel.
2.3 Local Buckling in HSS
This paper [3] investigates the compressive and local buckling behavior of hot-finished and cold-formed high-
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 06 | Jun 2025 www.irjet.net p-ISSN: 2395-0072
strengthsteel(HSS)squareandrectangularhollowsections. Tensile tests, stub column tests, and imperfection measurements were performed on several HSS grades. Resultsshowedthatcold-formedsectionshadhigheryield strengthduetocornereffectsbutlowerductilityandgreater imperfections.
The study evaluated Eurocode 3 design rules for HSS, focusingonductilitylimits,slendernessclassifications,and width reduction formulas. It found current provisions conservative and proposed adjustments, especially for extendingdesignguidancetohigherstrengthsteels.
2.4 CSM for HSS tubes
This paper extends the Continuous Strength Method (CSM) for designing high strength steel (HSS) tubular sections(CHS,SHS,RHS,EHS)undercompressionwhichis authoredasshownin[4].Itaddressestheshortcomingsof currentdesigncodesbyincorporatingstrainhardeningand elementinteraction.ExtensiveFEanalysisandexperimental datawereusedtodevelopnewbasecurvesandvalidatethe methodforsteelgradesupto1405MPa.
TheproposedCSMwascomparedwithexistingcodesand showedmoreaccurateandconsistentstrengthpredictions for both non-slender and slender sections. It offers a simplified, efficient design approach for HSS tubular members,supportingitsbroaderadoption.
2.5 Buckling of S960 Channels
Wang and Liang in this paper [5] investigates flexuralbucklingbehaviorofpin-endedpress-brakedS960 ultra-high strength steel channel columns. Experimental tests and validated finite element models examined two orientations-‘C’ (buckling toward webs) and ‘reverse C’ (toward flanges). Columns in the reverse C orientation showedhigherload-carryingcapacity.
Abroadparametricstudyassessedtheapplicability of EC3, AISI S100, and AS/NZS 4600 codes. EC3 was conservative,especiallyforreverseCcases,whileAISIand AS/NZSgavemoreaccuratebutoccasionallyunconservative predictions.Thestudyrecommendsrefiningdesignrulesfor S960UHSScolumns.
2.6 Flexural Buckling of S960 I sections
Thisstudy[6]investigatestheminor-axisflexural bucklingbehaviorofS960ultra-highstrengthsteelweldedIsectioncolumnsthroughdetailedexperimentsandvalidated FE models. Ten pin-ended column tests were performed along with measurements of material properties, residual stresses,andinitialimperfections.Resultsconfirmedthatall specimens failed by minor-axis flexural buckling, and numerical models accurately captured the structural response.
Design resistance predictions from current standards EC3,AISC,andAS4100 wereassessedusing the test and FE data. EC3 and AS 4100 gave overly conservativeresults,whileAISCofferedmoreaccuratebut slightly conservative predictions for short columns. A revised EC3 buckling curve (‘curve a’) was proposed, yielding much better agreement with experimental and numericalresultsforS960columns.
2.7 Buckling of S960 I Columns
This study of S960 I columns in [7], presents detailedexperimentalandnumericalanalysisofS690highstrength steel welded I-section columns under minor-axis flexural buckling. Ten pin-ended column tests were performed, along with measurements of geometric imperfections,materialproperties,andresidualstresses.FE models developed in Abaqus were validated against test results and used for parametric studies, covering a wide rangeofcross-sectiondimensionsandlengths.Allspecimens failedbyminor-axisflexuralbuckling,andnumericalresults closelymatchedtheexperiments.
ThestudycomparedpredictionsfromEN1993-112,ANSI/AISC360-16,andAS4100againsttest/FEdata.It foundEC3andAS4100conservative,whileAISCwasmore accuratebutsometimesunconservativeforlongercolumns. A modified EC3 buckling curve ('curve a' with lower imperfectionfactor)wasproposed,whichyieldedimproved andsaferesistancepredictionsacrossallslendernessranges.
2.8 CFHSS under combined loading
ThispaperofCFHSSundercombinedloadingin[8] investigatesthebehaviorofcold-formedhigh-strengthsteel (CFHSS) tubular beam-columns (SHS and RHS) under combined compression and bending. A total of 51 short beam-columntestswereperformedonspecimenswithyield strengths of 700–900 MPa, subjected to varying eccentricitiestosimulatedifferentaxial-to-bendingratios. Thetestresults coveringstrength,deformation,andfailure modes were compared against design predictions from AISC, EC3, and AS 4100, with AISC giving the closest estimates.Theinfluenceofcold-formingoncornerstrength wassignificantandenhancedaxialandmomentcapacities.
A validated finite element model was developed usingmeasuredmaterialpropertiesandimperfectiondata.It successfully replicated load-rotation behavior and failure modes.Thestudyconcludedthatcurrentdesigncodesare generallyconservative,especiallyforcompactsections,and more accurate predictions can be achieved by refining interactioncurveendpoints.Theauthorsrecommendfurther parametric studies using FE models to enhance design provisionsforCFHSSundercombinedloading.
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 06 | Jun 2025 www.irjet.net p-ISSN: 2395-0072
2.9 Post-fire response of S700 tubes
Thisstudyin[9]investigatesthepost-firestructural behaviorandresidualstrengthofS700high-strengthsteel tubular stub columns under combined compression and bending. A test program involving heating, cooling, and eccentriccompressiontestswasconductedonSHScolumns, followed by material testing and geometric imperfection measurements.Allspecimensfailedbylocalbuckling,and theresultsshowedsignificantstrengthlosswithincreasing temperatureexposure,especiallybeyond600°C.
Finite element models were developed and validatedagainstthetestresults,thenextendedtoperform parametricstudies.Thestudyevaluatedtheapplicabilityof EC3,AISC,andAS4100designinteractioncurvesusingpostfire material properties. All three standards predicted residual strengths reasonably well, but AISC provided the most accurate and consistent predictions across crosssectionclasses.Thestudysupportsadaptingexistingdesign rulestopost-fireconditionsforhigh-strengthsteel.
2.10 Post-Fire Behavior of S700 Stub Columns
The post-fire behavior in the paper [10] presents experimentalandnumericalstudiesonS700high-strength steel (HSS) square and rectangular hollow section stub columns after exposure to high temperatures (30°C–1000°C). A total of 15 stub column tests were conducted, alongwithpost-firegeometricimperfectionmeasurements and tensile tests. Results showed that yield and ultimate strengthsdroppedsignificantlyabove600°C.Allspecimens failed by local buckling, and validated finite element (FE) modelsaccuratelycapturedthebehavior.
DesignrulesfromEN1993-1-12,AISC360-16,and AS 4100 were assessed for post-fire strength predictions. Whileallthreecodesworkedwellfornon-slendersections, EC3andAISCoverestimatedstrengthforslenderonesdueto unsafeeffectivewidthformulas.AS4100providedaccurate and safe predictions across all section types and temperatures, making it more suitable for post-fire HSS design.
3. RESULTS AND DISCUSSIONS
1. Thestudyconcludesthatcurrentdesigncodesare conservativeforcompactHSSsectionsbutrequire refinement for slender ones to accurately reflect theiraxialperformance.
2. The study concludes that modified DSM provides themostaccuratestrengthpredictionsforYSt–310 cold-formed steel stub columns, especially for slendersections.
3. ThepaperconcludesthatEurocode3designrules are conservative for HSS sections and need
adjustmentstobetteraccommodatehigherstrength grades.
4. This research concludes that the extended CSM offers more accurate and consistent strength predictionsthancurrentcodes,makingitareliable designmethodforHSStubularsections.
5. The paper concludes that existing design codes needrefinement,asEC3isoverlyconservativeand AISI/AS/NZSarevariablyaccurateforS960 UHSS channel columns, especially in reverse C orientation.
6. The investigation concludes that existing design codesareconservativeforS960I-sectioncolumns, andarevisedEC3bucklingcurveoffersimproved accuracy for minor-axis flexural buckling predictions.
7. The work concludes that EC3 and AS 4100 are conservative for S690 I-section columns, while a modifiedEC3 bucklingcurveimprovesprediction accuracyacrossallslendernesslevels.
8. Thepaperconcludesthatcurrentdesigncodesare conservativeforCFHSSbeam-columns,andrefining interaction curve endpoints improves prediction accuracy,particularlyforcompactsections.
9. The study concludes that AISC offers the most accurate post-fire strength predictions for S700 stub columns, supporting adaptation of existing designrulesforfire-exposedhigh-strengthsteel.
10. The analysis concludes that AS 4100 provides accurateandsafepost-firestrengthpredictionsfor S700HSSstubcolumns,whileEC3andAISCtendto overestimatestrengthforslendersections.
4 CONCLUSIONS
The collective findings highlight that current international design codes such as EC3, AISC, and AS/NZS tendtoofferconservativepredictionsforcompact high-strengthsteel(HSS)sectionsbutoftenlackaccuracyfor slender members. Notably, the Eurocode was repeatedly foundtobeoverlyconservativeorunsafeinslendersection cases,whileAISCshowedbetteraccuracyinsomescenarios, especiallyforshortcolumns.Modificationsliketheimproved DirectStrengthMethod(DSM)forYSt–310andrevisedEC3 bucklingcurvesforS690andS960sectionsdemonstrated significant potential in enhancing prediction reliability acrossarangeofstructuralconfigurationsandslenderness levels.Additionally,theContinuousStrengthMethod(CSM) emergedasapromisingalternative,offeringmoreconsistent anddeformation-basedstrengthestimatesforHSStubular sections.
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 06 | Jun 2025 www.irjet.net p-ISSN: 2395-0072
Post-fire behavior studies further revealed the limitationsofambient-temperature-baseddesignprovisions, especially for S700 stub columns subjected to elevated temperatures. While all three codes EC3, AISC, and AS 4100 performedreasonablywellfornon-slendersections, AS4100consistentlyprovidedthesafestandmostaccurate post-fire resistance predictions across temperatures and cross-section types. These insights support the need for refined or new design approaches that better reflect the behaviorof modernhigh-strengthandultra-high-strength steels, particularly under complex loading and post-fire conditions.
5 ABBREVIATIONS
MPa - MegaPascal
Yst - YieldStress
REFERENCES
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