International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
Comparative Study on High-Rise RCC and Steel Seismic-Resistant Structures Using Bracing Systems
Tulluri Vishnu Vardhan 1, Dr D.V. Prasada Rao 2
1PG Student, Department of Civil Engineering, Sri Venkateswara University College of Engineering, Tirupati, Andhra Pradesh, India.
2Professor, Department of Civil Engineering, Sri Venkateswara University College of Engineering, Tirupati, Andhra Pradesh, India. ***
Abstract - The need of high-rise buildings in seismically active areas predetermines the necessity of effective lateral loadresisting systems. The present study assesses the seismic behaviour of the reinforced concrete (RCC) and steel buildings of ten and fifteen storeys with four types of bracing options: Cross-bracing, V-bracing, Chevron-bracing and single-bracing. The models were analysed as per IS 1893:2016. The equivalent static method and response spectrum method were used to evaluate the seismic response parameters such as the storey displacement, inter-storey drift, base shear, and the fundamental time period. The Cross-bracing and Chevron-bracing were found to be most effective among the systems studied and minimised the drifts, whereas the V-bracing and the single-bracing performed poorly. It is concluded that the choice of the best bracing arrangements is critical for the stability of high-rise buildings in seismic-prone areas.
Key Words: Seismic design; High-rise buildings; Bracing systems; RCC structures; Steel structures
1. INTRODUCTION
High-rise buildings have become one of the most characteristic features of the new urban development. Building Constructionisgrowingverticallyduetothehighrateofpopulationgrowthandscarcityofland.Thelateralforcesacting duetowindandearthquakearecriticaltohigh-risestructures,whicharecharacterisedbybuildingsraisedabove15mby theNationalBuildingCodeofIndia(NBC)[1].Incontrasttogravityloads,whicharenon-dynamicandpredictable,seismic forcesaredynamicanddisastrousand,therefore,oneofthemainfocusareasofstructuraldesign.
Oneofthemosteffectivesolutionstotheissueofseismicresistancehasbeenrecognisedasbracingsystemsthatincrease the stiffness and strength without being too costly [2]. These systems are fabricated out of thin steel members, and they transmit lateral forces mainly by axial tension and compression. Bracing systems can significantly reduce inter-storey drift,lateraldisplacementandbasictimeperiodsdependingontheirarrangement[2].
According to IS 1893:2016, seismic zoning of India defines four zones, and such areas as the Himalayan belt, North-East India, and Gujarat are the most susceptible ones [3]. It has been observed that bare frames are not sufficient to resist seismic forces and that they require auxiliary systems like shear walls, outriggers, and bracing [4,5]. Shear walls are stiffening and may have restrictive effects on architecture, as compared to bracing systems, which are flexible and availableasretrofitoptions[6].
ThestudyexplorestherelativeeffectivenessofCross-bracing,V-bracing,Chevronbracing,andsinglebracingusedinRCC and steel buildings with ten and fifteen storeys. Their effectiveness in the seismic response can be assessed using structuralmodellingusingETABS.
2. LITERATURE REVIEW
Seismic loading of high-rise structures has received extensive research on performance. Norharsi et al., [7] showed that ultrasonic pulse velocity, as another non-destructive testing method, can be used to evaluate in-situ concrete properties effectivelyintallbuildings,whichiswhystrongmaterialsarevitalinseismicperformance.Acomparisonofseismicdesign provisions in the Indian and European standards by Tapkire and Birajdar [6] indicated that, in the Indian and European standards,ductilityclassesandfactorsofresponsereductiondiffereddirectly,andthisimpactsseismicresilience.
Variousbracingdesignsare investigated.Shahrzad et al., [5]discoveredthatinvertedV-bracingwasthemostefficientin terms of utilisation of material and still offered sufficient stiffness, but single bracing offered better energy absorption, withthedisplacementsbeinggreater.MaheriandSahebi[2]experimentallydemonstratedthatCross-bracingwascapable of increasing the lateral load resistance of RC frames three times that of unbraced systems. Subsequent research, like
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
NaumanandIslam[8],verifiedthatcross-bracingandchevronbracinghadagreateffectonminimisingthedisplacements infifteen-storeyRCCframes.
Maheri and Hadjipour [9] experimentally assessed direct steel brace connections to RC frames, and Maheri and Yazdani [10] showed that the Uniform Force Method could be applied in designing brace connections with RC frames. It has also beendemonstratedthatcompositestructuralsystems,includingconcrete-filledsteeltubes(CFST),canprovideenhanced seismicresiliencybecauseofconfinementeffectsandenhancedenergydissipation[11,12].
TheapplicationofETABShasenabledtheprecisepredictionofseismicresponse.Sallal[13]andGuleria[14]emphasised that the computational models offer crucially important information on the drifts, displacements and torsional irregularitiesofstorey,allowingformakingreliablecomparativeanalysisonbracingsystems.
On the whole, the literature points to three consistent conclusions: (i) bare frames do not work well when subjected to seismicloading,(ii)cross-bracingandinvertedV-bracingtendtobemostefficient,and(iii)goodconnectiondetailingand compositeelementsaddtotheresilienceofthestructure.
3. METHODOLOGY
The methodology used in this study is to obtain the seismic performance in terms of inter-storey drift of high-rise buildings with and without a bracing system. The general strategy entailed in the process was the choice of the representative models of buildings, the definition of geometric and material properties, using different types of bracing configurations, application of gravity and seismic loads as per IS codes, and the structural analysis implementation in ETABSsoftware.Theobtainedresultswerecomparedtoevaluatetherelativeeffectivenessofvariousbracingsystemson bothreinforcedconcrete(RCC)andsteelframesofdifferentheights.
Twodifferentheightsofthebuildingmodelswereusedtocapturethecontributionofslendernessanddynamicbehaviour. Theformermodelwasaten-storeybuilding,andthelatterwasafifteen-storeybuilding.Theplandimensionsof13.04m× 14.71m were used in both models, and the typical storey height of the building is 3.2m. M30 grade concrete and Fe500 gradesteelreinforcementwereusedinRCCmodels,andsteelmodelsweredevelopedwithE350structuralsteelasperIS 2062:2011[15].Structural elementswereestablished basedonpreliminarydesign,wheretheslabsareofa thicknessof 150mm,theexternalwallis230mmthick,andtheinternalwallandparapetwallare115mmthick.Inthepresentstudy, theinfluenceoffourkindsofbracingwasinvestigated:Cross-bracing,V-bracing,Chevron-bracingandsinglebracing.The sectionalsizesofbracingmembersareselectedbasedonIScodesforductiledetailingofbothRCCandSteelstructures.
Seismic analysiswascarriedoutasperIS1893:2016. Azonefactor(Z)wastakenas0.16forseismiczoneIII,whichisa medium seismic hazard. An important factor (I) of 1.0 and a response reduction factor (R) of 5.0 and 4.5 for Special MomentResistingFrame(SMRF)andSpecialConcentricBracedFrame(SCBF),respectively[3].
Two types of analysis techniques were used: the Equivalent Static Method (ESM) and the Response Spectrum Method (RSM).Inthecorrespondingequivalentstaticmethod(ESM),thenaturalperiodofthebuildingswasestimatedempirically withtheexpressionofIS1893:2016[3].Thisproducedperiodsof0.80s(X)and0.75s(Y)intheTen-Storeystructure,and 1.196 s (X) and 1.126 s (Y) in the Fifteen-Storey structure. These were the values employed to calculate design seismic forcesandtheirverticaldistributionthroughthestoreys.Intheresponsespectrumanalysis,aminimumoftwelvemodes weretakenintoaccounttoobtainover90%cumulativemassparticipationasperIS1893:2016[3].Themodeshapeswere associatedwiththetranslationalmotionsinXandYdirections,andtorsionalmotionswereobservedinthehighermodes.
The Gravity loads were adopted according to IS 875:1987 [16]. Self-weight of structural elements, 1.5 kN/m2 for floor finishes, and wall loads were included as dead loads. Live load was assumed to be 3.0 kN/m2 on typical floors and 1.5 kN/m2 ontheroof.GravityandseismicloadscombinationswereconsideredbasedonIS456:2000 andIS800:2007,they are1.5(DL+LL),1.2(DL+LL±EQ)and1.5(DL+LL±EQ),aswellas0.9DL±1.5EQ.
The evaluation of the seismic performance of the structures was done regarding four important parameters: Maximum storey displacement, Inter-storey drift, base shear and fundamental natural period. The allowable drift was restricted to 0.004timesthestoreyheight,andthisbuildingmodelhad12.8mm,correspondingtoa3.2mstoreyheightofthebuilding. Equally, the displacement of the top storey of the structure was compared against the limit of H/250, which gives the valuesof128mminthecaseoftheTen-storeystructureand192mminthecaseoftheFifteen-storeystructure.Itcanbe seenthatthecodalrequirementsaresatisfied.
International Research Journal of Engineering and
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4. ANALYSIS
2395-0072
Seismicanalyseswerecarriedoutonbuildingmodelsusingboththeequivalentstaticmethodandtheresponsespectrum methodasperIS1893:2016[3].
Table-1: NaturalTimePeriodforRCCstructureswithvariousBracingsystems
5. RESULTS AND DISCUSSION
Table-2: ComparisonofSeismicParametersofaTen-storeyedConcreteStructurewithVariousBracingSystems Ten-StoreyedConcreteStructure
inY-Direction
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
Chart -1: PercentageReductionofMaximumStoreyDisplacementAcrossVariousBracingSystemsinaTen-storyConcrete StructureinEQXandEQYForces
Chart-2: PercentageReductionofMaximumInter-StoreyDriftAcrossVariousBracingSystemsinaTen-storeyedConcrete StructureinEQXandEQYForces
Table-3: ComparisonofSeismicParametersofaFifteen-storeyConcreteStructurewithVariousBracingSystems
ConcreteStructure
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
Chart-3: PercentageReductionofMaximumStoreyDisplacementAcrossVariousBracingSystemsinaFifteen-storey ConcreteStructureinEQXandEQYForces
Chart-4: PercentageReductionofMaximumInter-StoreyDriftAcrossVariousBracingSystemsinafifteen-storeyConcrete StructureinEQXandEQYForces
Table-4: ComparisonofSeismicParametersofaTen-storeySteelStructurewithVariousBracingSystems
SteelStructure
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
Chart-5: PercentageReductionofMaximumStoreyDisplacementAcrossVariousBracingSystemsinaten-storeySteel StructureinEQXandEQYForces
Reduction in InterStorey Drift
Chart-6: PercentageReductionofMaximumInter-StoreyDriftAcrossVariousBracingSystemsinaten-storeySteel StructureinEQXandEQYForces
Table-5: ComparisonofSeismicParametersofaFifteen-storeySteelStructurewithVariousBracingSystems
Steelstructure
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
Chart-7: PercentageReductionofMaximumStoreyDisplacementAcrossVariousBracingSystemsinafifteen-storeySteel StructureinEQXandEQYForces
Chart-8: PercentageReductionofMaximumInter-StoreyDriftAcrossVariousBracingSystemsinafifteen-storeySteel StructureinEQXandEQYforces
A key observation is that RCC structures, owing to their inherent stiffness, exhibit lower absolute displacements and driftscomparedtotheirsteelstructures.Forinstance,theunbracedfifteen-storeyRCCstructurehasaroofdisplacement of87mm,whereasthesteelstructurehas179mm.Thishighlightsthatsteelstructuresrelymoreonbracingforstability. When bracing is introduced, particularly Cross-bracing, both structures show substantial reductions. The percentage reductionindisplacementismoreinsteelframes(60–65%)thaninRCC(30–40%),reflectingthefactthatflexibleframes gain more from stiffening. Chevron bracing and V-bracing are emerging as a reliable alternative, delivering reductions nearlycomparabletoCross-bracing,whilesinglebracingconsistentlyunderperformsinthestructures.Inter-storeydrift follows the same trend, with bracing ensuring compliance with the codal limit of 0.004h (≈12.8 mm for ten-storey and ≈19.2mmforfifteen-storey).Anotherimportantfeatureisthatthebaseshearincreaseswithbracingacrossallmodels.In conclusion,Cross-bracingis universallythemost effective,Chevronbracingand V-bracingaremoderatelyeffective,and single-bracing systems provide only marginal benefits. The comparison confirms that bracing selection plays a decisive roleinensuringseismicresilience,especiallyinhigh-risestructureswheretheunbracedperformanceisunsatisfactory.
6. CONCLUSIONS
BasedontheresultsoftheanalysesoftheRCCandSteelstructuresthefollowingaretheconclusions:
For a ten-storeyed RCC structure, the roof and inter-storey displacements are reduced by 33.5% and 36% in a cross-bracedstructurewhencomparedtoanunbracedstructure.
For a fifteen-storey Steel structure, the roof displacement is reduced by 63% in a cross-braced structure when comparedtoanunbracedstructure.
TheanalysedRCCandSteelstructureswiththeChevronbracingsystemindicateapproximately15%to 25%and 40%to60%reductionininter-storeydriftcomparedtoanunbracedstructure.
Single bracing system results in approximately 10 to 20% and 35 to 50% reduction of inter-storey drift for an RCCandsteelstructures,respectively.
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025 www.irjet.net p-ISSN: 2395-0072
Braced RCC structures exhibited reduced roof displacement, but the reduction is moderate, whereas unbraced steelstructuresexhibitmoreroofdisplacement,butthereductionismoreinthecaseofbracedstructures
For both RCC and Steel structures, a cross-braced system can be considered as an effective solution in severe seismicregions.
REFERENCES
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