Ijciet 10 01_032

Ijciet 10 01_032

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  http://www.iaeme.com/IJMET/index.asp 342 [email protected] InternationalJournal of Civil Engineering and Technology (IJCIET) Volume 10, Issue 1, January 2019, pp.342–355, Article ID: IJCIET_10_01_032 Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=1 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 ©IAEME Publication Scopus Indexed ASSESMENT OF SEISMIC PERFORMANCE FOR G+5 MULTI-STOREY BUILDING WITH BRACINGS AT DIFFERENT STORIES T.S.D. Phanindranath Research Scholar, Department of Civil Engineering, GITAM University, Visakhapatnam, Andhra Pradesh, India Assistant Professor (c) University College of Engineering Vizianagaram (JNTU-K UCEV) Vizianagaram, Andhra Pradesh, India Balaji K.V.G.D Professor, Department of Civil Engineering, GITAM University, Visakhapatnam, Andhra Pradesh, India PoleswaraRao, Kovela Research Scholar, Department of Civil Engineering, GITAM University, Visakhapatnam, Andhra Pradesh, India ABSTRACT The main aim of this paper is to identify the type of bracing for the better seismic performance of the structure by building steel bracings at different floor levels.Duringearthquakes the human loss is mainly due to the failure of structures. Seismic deficitstructures will crumble even at low magnitude earthquakes.Many existing structures need to be retrofitted,installation of steel bracing for existing structure will be easiest way instead of buildingshear walls.Steel tubular X-bracing system have been installed to the strcuture at different floor levels for choosen G+5 RCC building and analyzed by Non-linear static push over analysis.Six cases are considered in this study, in each case the placement of bracing were changed to find out the better performane of the structue with variation in the placement of bracings at different storey levels.The comparisions made between these six cases by keeping base model as ideal model along with the parameters like base shear,displacement and inter-storey drift.After comparing it was found that there is a significant increase of Base Shear by 14.90%,16.53% for case-3,case-5 models respectively when compared with basemodel i.e. case-1with out bracing. The displacement is reduced by 17.39%, 17.39% for case-3 and case-5models respectively when compared with base model. There is a reduction of inter-storey drift by 33.33%, 33.33% for case-3 and case-5 models respectively when compared with base model. Case-3 and case-5 braced frames has been significantly performed well with the reduction in storey drifts and displacements and increase in base shear.
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 343 [email protected] Keywords: Push Over Analysis, Bracings, Sesimic Performance of Multistorey Building,Placement of Bracings,Base Shear,Displacement,Storey Drift, Storey Level. Cite this Article: T.S.D. Phanindranath, Balaji K.V.G.D, PoleswaraRao and Kovela, Assesment of Seismic Performance for G+5 Multi-Storey Building with Bracings at different Stories, International Journal of Civil Engineering and Technology (IJCIET), 10 (1), 2019, pp. 342–355. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=1 1. INTRODUCTION 1.1. General Structure may experience sesimic forces occasionaly during its life time.When an existing structure is designed only for gravity loads or incapable of resisting the lateral loads induced due to earth quake loads, it should be able towithstand seismic loads without any structural damage.The implementation of earthquake design is important in high seismic zones and evenfor tall structures in low sesimic zones.To avoid human and property loss the structure should be checkedas per the revised seismic code. Various lateral load resisting systems are available even for existing structures The behaviours of structure under seismic load is studied to select theconfiguration of resisting system.It is important to know the behaviour of structure due to sesimic loads and finding out the type of resisting system and configuration of resisting system.The major common problem in the structure is lateral stability especially with5 or 6 stories structures.Displacement is aconcern parameter in the tall structures which disturbs the structure and increases the chance of major failure in structural elements.If the same structure experiences consecutive earthquakes there might be a chance of failure of the structure, due to the execssive deflections in weak structural elements. The columns of RCC structure will resist lateral loads, including wind and seismic loads. Steel moment frames like bracings will improve resistance capacity of lateral loads through flexural strength of members. Bracing members will resist lateral loads by transferring axial forces both compression and tension through diagonal bracing members.These bracings will transfer loads from roof or floor diaphragms through shear connections and to foundation A few common configurations are cross bracings, chevron bracing, V-bracing, single diagonal bracing, double diagonal bracing etc. The configuration of bracings in a structure may show the variation in the resistance criteria.Due to the changes in the placement of bracings, base shearand inter-storey driftwill exhibit considerable varaition.So the placement of bracings will also play a crucial role in the determination of results. As the name indicates Push over analysis pushes the structure unitl the maxiumum capacity of the building is reached.In case of earthquake loads this analysis leads to the determination of deformation and cracking of the structure.The formation of plastic hinges can also be studied which throw light on the failure pattern of the structure. Push over analysis is an approximate tool to understand the building performance under non linear static analysis and gets the capacity of the building for maximum displacement. Various research papers are availble in the scope of this work Hendramawat A Safariki et.al[3]evaluated the improvement of sesimic performance for RCC existing structure with the installation of steel bracing.In this work three methods are adopted for the seismic evaluation,Nonlinear static push over displacement coefficient method as explained in FEMA 356, Nonlinear static pushover displacement coefficient method as described in FEMA440 and dynamic time history analysis following indonesian code of seismic resistance building
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  T.S.D. Phanindranath, BalajiK.V.G.D, PoleswaraRao and Kovela http://www.iaeme.com/IJCIET/index.asp 344 [email protected] criteria.The displacement determined from non linear push over analysis of the existing building is 0.188m in X-direction and 0.132m in Y–direction.The performance of the existing building could be improved by introducing steel bracings.Displacements are reduced by 16% –55% if the proposed steel braces are used.MagudeaswaranPalanisamy et.al[7] concluded that steel structures will have more advantages when compared with RCC structures because of its cost efficient, sustainable, durable, ductile and safe. To analyze dynamic behavior of the structure due to dynamic loads non–linear behavior of the structure is to be considered. The non-linear performance of the structure can be determined by push over analysis. In this work the push over analysis is carried out to two frames namely bare frame and steel frame using Ansys software under lateral loading and it is validated experimentally. Yield load and ultimate load for steel braced frame is greater and deflection for steel braced is less when compared with bare frame due to increase its diagonal stiffness of the frame. DhangarLaxmiBalappa et.al [2] concluded that the buildings may collapse in the event of earthquake even if they appear strong enough. The building collapsed in the bhuj earthquake is seismic deficient structure, which is not constructed in the favor of seismic code. To determine the performance of framed buildings under expected earth quakes a non-linear static push over analysis has been conducted. In this work 4 models of G+10 has been prepared with and without bracings and analyzed in SAP 2000 software. The results compared in terms of base shear, displacements, time period, location of hinges and push over curves obtained from the study shown the improved performance of the braced structure when compared with bared structure. Prince kaley et.al [9] determined the seismic performance of multi storied building according to IS 800-2007.By introducing steel bracing system to the structure the ductility of the structure can be increased. Different types of bracings like X, V, Inv-V, diagonally braced configurations have been introduced to structure.G+9 multistory steel building has been modeled with and without bracings. By using SAP 2000 software nonlinear static analysis (push over analysis) has been run for these models. Various parameters like mode shapes, frequencies, mode shapes, deformed shapes, hinge results are compared between braced and bare models to determine the relative performance of selected models. 1.2. Objective of the work The main objective of the study is to improve the resistance capacity of the structure in terms ofbase shear, storey displacements and inter storey drifts by introducingsteel bracings to the structure and aslo to identify the configuration of bracings in the strcuturewhich offers maximun advantage with minimun number of bracing patterns. 1.3. Scope of the work The scope of the work is shown by the following models.
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 345 [email protected] Figure 1.1 With Out BracingFig-1.2 Bracings at Cellar level Figure 1.3 Bracings at Cellar and 2nd Storey Figure 1.4 Bracings at First Storey Figure 1.5 Bracings at First and 4th Storey Figure 1.6 Bracings for Entire Structure
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  T.S.D. Phanindranath, BalajiK.V.G.D, PoleswaraRao and Kovela http://www.iaeme.com/IJCIET/index.asp 346 [email protected] In the first case no bracings are provided to the structure and it is taken as refernce for comparision.In the second case bracings are erected only at cellar level,bracings are erected for cellar and to second storey in the third case. In fourth case bracings are installed only at first storey, and for fifth case bracings are installed at first and fourth storey, for the last model i.e, sixth case bracings are erected to the whole structure. 2. STRUCTURE MODELLING Dead loads, live loads and load combinations are assigned to the structure to generate required models (6 cases) with same structural element specifications. Steel X-Bracing system with tubular cross section is installed by varying storey levels as shown in the previous figures.Non–linear static push over analysis has been run to all the 6 cases to determine the capacity of the structure. 2.1. Material property Table 2.1 properties of the material Concrete grade M25 Steel grade Fe415 Compressive strength of concrete 25 N/mm2 Yeild strength of main reinforcement 415 N/mm2 Yeild strength of bracing members 250 N/mm2 Density of rcc 25 kN/ m3 Density of steel 7850 kg/m3 2.2. Member property Table 2.2 properties of the structural elements Slab thickness 150 mm Beam size 230 mm x 450 mm Column size 300 mm x 450 mm 2.3. Description of model Table 2.3 Model description Number of stories G+5 Floor height 3m Buiding height 18m width of the bay in X-direction 5m x 4 bays=20m width of the bay in Z-direction 4m x 8 bays =32m Buidling area 640 m2 Building type OMRF and SMRF (residential) Live load 2kN/ m2 Dead load of slab 4 kN/ m2 Load for inner walls(4.5’’) 5 kN/ m Load for external walls(9’’) 6.8 kN/ m Dead load for beams in x-direction 2.60 kN/ m Dead load for beams in y-direction 2.60 kN/ m
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 347 [email protected] 2.4. Modeling of Bracing Member As per IS 15988.2013 [6] code specifications tubular section was adopted due to its high moment of inertia and radius of gyration for same cross sectional areas while compared with angular and channel sections.The ratio of end to end width of member to the wall thickness should not exceed 288/√fy for tubular section [6]. Therefore depending upon the code specifications the cross section has been adopted for tubular section. Figure 2.1 Tubular Cross Section 2.5. Property of steel section Table 2.4 Steel sectional properties Weight per meter length (kg) 4.09 Area of cross section (mm2 ) 505 Moment of inertia (m4 ) 1.227 x 10-7 Modulus of section (m3 ) 6.130 x 10-6 Shear area (mm2 ) 300 Radius of gyration (mm) 15.6 3. RESULTS AND DISCUSSIONS 3.1. Base Shear Table 2.5 Base shear for various cases CASE BASE SHEAR (kN) Case-1 7221 Case-2 7364 Case-3 8297 Case-4 7675 Case-5 8415 Case-6 9975
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  T.S.D. Phanindranath, BalajiK.V.G.D, PoleswaraRao and Kovela http://www.iaeme.com/IJCIET/index.asp 348 [email protected] Figure 3.1 Base Shear  For case-2 the Base Shear is increased by 2.00% when compared with case-1  For case-3 the Base Shear is increased by 14.90% when compared with case-1  For case-4the Base Shear is increased by 6.28% when compared with case-1  For case-5 the Base Shear is increased by 16.53% when compared with case-1  For case-6 the Base Shear is increased by 38.13% when compared with case-1 3.2. Displacement &Storey Drift Case-1 Table 3.1. Displacement and Inter Storey Drift for Case-1 Storey Height (m) Displacement (mm) Inter Storey Drift (mm) Allowable Inter Storey Drift (mm) (0.004xh) Sixth floor 46 04 12 Fifth floor 42 04 12 Fourth floor 38 06 12 Third floor 32 06 12 Second floor 26 12 12 First floor 14 08 12 Ground floor 06 06 12 Plinth level 00 00 12
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 349 [email protected] Figure. 3.2. Displacement of Base Model Case-2 Table 3.2. Displacement and Inter Storey Drift for Case-2 Storey Height (m) Displacement (mm) Inter Storey Drift (mm) Allowable Inter Storey Drift (mm) (0.004xh) Sixth floor 44 06 12 Fifth floor 38 05 12 Fourth floor 33 06 12 Third floor 27 09 12 Second floor 18 10 12 First floor 08 06 12 Ground floor 02 02 12 Plinth level 00 00 12 Figure3.3 Displacement of Case-2 Model
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  T.S.D. Phanindranath, BalajiK.V.G.D, PoleswaraRao and Kovela http://www.iaeme.com/IJCIET/index.asp 350 [email protected] Case-3 Table 3.3 Displacement and Inter Storey Drift for Case-3 Storey Height (m) Displacement (mm) Inter Storey Drift (mm) Allowable Inter Storey Drift (mm) (0.004xh) Sixth floor 38 03 12 Fifth floor 35 03 12 Fourth floor 32 08 12 Third floor 24 08 12 Second floor 16 07 12 First floor 09 05 12 Ground floor 04 04 12 Plinth level 00 00 12 Figure 3.4 Displacement of Case-3 Model Case-4 Table 3.4. Displacement and Inter Storey Drift for Case-4 Storey Height (m) Displacement (mm) Inter Storey Drift (mm) Allowable Inter Storey Drift (mm) (0.004xh) Sixth floor 41 03 12 Fifth floor 38 05 12 Fourth floor 33 05 12 Third floor 28 10 12 Second floor 18 08 12 First floor 10 05 12 Ground floor 05 05 12 Plinth level 00 00 12
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 351 [email protected] Figure 3.5 Displacement of Case-4 Model Case-5 Table 3.5 Displacement and Inter Storey Drift for Case-5 Storey Height (m) Displacement (mm) Inter Storey Drift (mm) Allowable Inter Storey Drift (mm) (0.004xh) Sixth floor 39 02 12 Fifth floor 37 07 12 Fourth floor 30 03 12 Third floor 27 07 12 Second floor 20 08 12 First floor 12 06 12 Ground floor 06 06 12 Plinth level 00 00 12 Figure 3.6 Displacement of Case-5 Model
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  T.S.D. Phanindranath, BalajiK.V.G.D, PoleswaraRao and Kovela http://www.iaeme.com/IJCIET/index.asp 352 [email protected] Case-6 Table 3.6 Displacement and Inter Storey Drift for Case-6 Storey Height (m) Displacement (mm) Inter Storey Drift (mm) Allowable Inter Storey Drift (mm) (0.004xh) Sixth floor 30 02 12 Fifth floor 28 04 12 Fourth floor 24 03 12 Third floor 21 03 12 Second floor 18 06 12 First floor 12 06 12 Ground floor 06 06 12 Plinth level 00 00 12 Figure 3.7 Displacement of Case-6 Model
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 353 [email protected] Figure 3.8 Displacement for Various Cases at each storey level Figure 3.9 Displacement for Various Cases at Top Storey  For case-2 the Displacement is reduced by 4.34% when compared with case-1  For case-3 the Displacement is reduced by 17.39% when compared with case-1  For case-4 the Displacement is reduced by 10.86% when compared with case-1  For case-5 the Displacement is reduced by 17.39% when compared with case-1  For case-6 the Displacement is increased by 34.78% when compared with case-1
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  T.S.D. Phanindranath, BalajiK.V.G.D, PoleswaraRao and Kovela http://www.iaeme.com/IJCIET/index.asp 354 [email protected] Figure 3.10 Inter Storey Drift for Various Cases Figure 3.11 Maximum Inter Storey Drift in Each Case  For case-2 the Inter-Storey Drift is reduced by 16.66% when compared with case-1  For case-3 the Inter-Storey Drift is reduced by 33.33% when compared with case-1  For case-4 the Inter-Storey Drift is reduced by 16.66% when compared with case-1  For case-5 the Inter-Storey Drift is reduced by 33.33% when compared with case-1  For case-6 the Inter-Storey Drift is reduced by 50.00% when compared with case-1 CONCLUSIONS Non-linear static analysis (push over analysis) has been run to compare the results between models to find out the effective configuration of bracing system for selected cases. The base model experiences high displacement and high inter-storey drift with less attraction of base shear. By introducing X-configuration bracing system into the structure the selected parameters like displacement, inter-storey drifts has been reduced with a considerable increase of base shear. There is an increase of Base Shear by 14.90% for case-3 when compared with base model i.e. case-1.For case-5 the Base Shear is increased by 16.53% when compared with case-1.
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  Assesment of SeismicPerformance for G+5 Multi-Storey Building with Bracings at different Stories http://www.iaeme.com/IJCIET/index.asp 355 [email protected] The displacement is reduced for case-3 model by 17.39% when compared with case-1.The displacement is reduced for case-5 model by 17.39% when compared with case-1.Inter storey drift is reduced by 33.33% for case-3 model when compared with base model. For case-5 the Inter-Storey Drift is reduced by 33.33 % when compared with case-1.Case -3 and case-5 braced frames has been significantly performed well with the reduction in storey drifts and displacement percentage and increase in base shear. Instead of installing bracing members along periphery of the model, finding out the configuration of bracing members between the storey levels which results in allowing the selected parameters up to permissible limits gives way to the reduction of quantity of braced members. Finding out the alternate configuration of bracing members can also reduce financial efforts. Determination of capacity of the structure and reducing the displacement, storey drift and enhancing the base shear capacity which gives way in the safety of the structure against dynamic loads by finding out the exact placement of bracing members in the structure. Case-3 and case5 models would be better alternative while resisting the earth quake loads effectively with less number of bracings REFERENCES [1] Braz-César M. T, Barros R. C,(2009) “Seismic Performance of Metallic Braced Frames By Pushover Analysis” , Computational Methods in Structural Dynamics and Earthquake Engineering. [2] DhangarLaxmiBalappa and VenuMalagavelli,(2018) “Pushover Analysis of High Rise Buildings With and Without Bracings” International Journal of Civil Engineering and Technology (IJCIET), Volume 9, Issue 9, pp. 759–767. [3] Hendramawat A Safarizkia , S.A. Kristiawanb, and A. Basuki(2013) “Evaluation of the Use of Steel Bracing to Improve Seismic Performance of Reinforced Concrete Building”The 2nd International Conference on Rehabilitation and Maintenance in Civil Engineering, science direct,pp. 447-456. [4] IS: 456-2000 Plain and reinforced concrete-code of practice. [5] IS: 800-2007 General construction in steel-code of practice. [6] IS: 15988:2013 Seismic evaluation and strengthening of existing reinforced concrete buildings-guidelines. [7] .P.Eswaramoorthi, P.Magudeaswaran, A. Dinesh (2016)”Pushover Analysis of Steel Frame”International Journal of Advanced Engineering Technology,Volume-7,Issue 2,April-June,2016, pp.1101-1103. [8] Mohammed Idrees Khan, Mr.KhalidNayaz Khan,(2014) “Seismic Analysis of Steel Frame With Bracings Using Pushover Analysis” International Journal of Advanced Technology in Engineering and Science, Volume-02, Issue- 07,pp.369-381. [9] Prince Kaley and MirzaAamirBaig(2017)” Pushover Analysis of Steel Framed Building” Journal of Civil Engineering and Environmental Technology, Volume 4, Issue 3; pp. 301- 306