40

International Journal of Research and Innovation (IJRI)

International Journal of Research and Innovation (IJRI)

ANALYSIS AND DESIGN OF RESIDENTIAL TOWER BY DYNAMIC ANALYSIS USING RESPONSE SPECTRUM METHOD

D.Ramarao1, K. Mythili2, G.Venkat Ratnam3

1 Research Scholar, Department Of Civil Engineering, Aurora's Scientific Technological & Research Academy, Hyderabad, India2 Associate professor , Department Of Civil Engineering, Aurora's Scientific Technological & Research Academy, Hyderabad, India3 Associate professor , Department Of Civil Engineering, Aurora's Scientific Technological & Research Academy, Hyderabad, India

*Corresponding Author: D.RAMARAO, Research Scholar, Department of CIVIL Engineer-ing, Aurora's Scientific Technological & Research Academy, Hyderabad, India Published: October 27, 2014Review Type: peer reviewedVolume: I, Issue : II

Citation:D.RAMARAO1,(2014)Analysis And Design Of Residential Tower By Dynamic Analysis Using Response Spectrum Method

BRIEF DESCRIPTION OF THE STRUCTURE

Proposed Structure consists of Residential Tower to be constructed at Gurgaon.

Salient Features of building are as follows.

Name New Town Heights at GurgaonLocation GurgaonType Residential Building

No.of floors 2B+ST+31 Floors

Design methodology:

S. No Points Description1 Structural

systemConventional beam slab arrangement

2 Method of analysis

Space frame method has been used for analysis of this structure, Software- E TABS

3 Foundation design

Conventional raft- SAFE software shall be used for the designing of raft.

Loads to be considered while designing:

1 Dead loads Sizes of structural members x density of concrete

25 kN/cum IS-875-I

a Floor finish load 1.2 kN/sqmb Water proofing Ter-

race load on terrace, Inclusive of brick batcoba

3.0 kN/sqm

Abstract

This Project Named As Analysis And Design Of Residential Tower (2basemetns+Stilt+31 Upper Floors)By Dynamic Analy-sis Using Response Spectrum Method Involves The Analysis And Design Of Residential Tower 3-D Frames Of Uniform

Floor heights for typical floors using very popular software tool ETABS 9.7.2.

The main thesis of this Project is to achieve the following:

1).To arrive at minimum number of modes required to get modal mass participating ratio more than 90% by dynamic analysis using Response Spectrum Method.2). To limit the lateral deflection at the top of the tower less than H/250(Where H = Height of the tower till terrace) for seismic load.3). To limit the Inter Storey Deflection(Storey Drift) in any storey due to the minimum specified design lateral force, with factor of 1.0 less than 0.004 times the storey height.

In addition to that the detailed study of seismology was undertaken and the feasibility of the software tool to be used was also checked. Till date many such projects have been undertaken on this very topic but the seismic analysis were generally done by static analysis but to this the seismic analysis is done by dynamic analysis for all possible load combinations pertaining to IS 456, IS 1893 and IS 13920.

1401-1402

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International Journal of Research and Innovation (IJRI)

2 Live load i)Living rooms, bed room kitchen & toilets etc.ii)Corridors, pas-sages & stairs iii)Balconies

2 KN/sqm.3 KN/sqm3 KN/sqm

IS-875-II

3 Masonry loads

External Wall loads(Concrete Blocks)Internal(Fly ash bricks)/ density

20 KN/sqm10 KN/sqm

Other Predominant Forces:S. No load4) Earth quake load.

a).Zone for Gurgaonb).Importance factorc). Type of structure d).Response Re-duction FactorSoil typeTime period to be used

V1SMRF52.00.075h^0.75

5) Wind loads.Basic wind pressure (Gurgaon)CategoryClass

47m/s2C

Soft Storey Due to Stilt:

To take care of soft storey due to stilt, besides the col-umns designed and detailed for the calculated storey shears and moments, shear walls shall be placed sym-metrically in both directions of the building as far away from the centre of the building as feasible, to be designed exclusively for 1.5 times the lateral storey force.

Dynamic analysis:

Dynamic analysis is being performed by the Response Spectrum Method. The design base shear (VB) shall be compared with a base shear (VBT) calculated using a fun-damental period Ta. Incase VB is less than VBT, all the response quantities are multiplied by scale factor. Detailing for ductility: As per the provisions of IS 13920.

Following load cases considered for design calcula-tion:

1.5(DL+LL), 1.2(DL+LL+SPEC X), 1.2(DL+LL+SPEC Y),1.2(DL+LL+WLXP),1.2(DL+LL+WLXN),1.2(DL+LL+WLYP),1.2(DL+LL+WLYN) 1.5(DL+SPEC X), 1.5(DL+SPEC Y),1.5(DL+WLXP), 1.5(DL+WLXN),1.5(DL+WLYP), 1.5(DL+WLYN).

Recommendation for construction materials:

S.No Construction Material Specification1 Reinforcement steel Fe 500 D (TMT)

(Ductile steel to be used)

2 Grade of concrete fora) Columns M40,M35,M30,M25 b) Foundations/rafts - M25 c) Retaining wall and tie beams M25d) Conventional beams M20,M40e) Conventional slabs M20

Ready Mix Con-crete

3 Type of Masonry: Concrete Block work for external walls and Fly ash brickwork for internal walls

4 Cement:OPC cement is preferable to use for important RCC work. In case of non-availability of OPC cement, PPC cement can be used.

Preference: Use OPC cementUnder constraint PPC cementFlyash not to be used

Covers for R.C.C Structures:Following values as recommended by IS.456-2000 and as per norms of NBC for fire resistance 2 hours.

S.No Specification1 Environmental condition Mild2 Covering IS 456- clause-26.4

a).Footings 50mmb). Rafts 50 mmc).Columns and Lift walls 40mmd).Slabs 20mm(valid for

1.5hrs)e).Beams 20mm (valid for 1.5

hrs)and dia of the bar whichever is maximum

Slabs and beams are additionally protected by plastering, floor-ing /water proofing Which helps to enhance fire resistance time further.

3 Retaining wall 40mm for soil side(1.5 hours ok for basement)25mm for other side

4 Water retaining walls To avoid corrosion in case of water proofing failure

50mm (for severe condition)

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International Journal of Research and Innovation (IJRI)

A seismic design of high rise buildings has assumed considerable importance in recent times.

In traditional methods adopted based on fundamen-tal mode of the structure and distribution of earth-quake forces as static forces at various stories may be adequate for structures of small height subjected to earthquake of very low intensity but as the num-ber of stories increases the seismic design demands more rigorous. [1]*

PHASES OF THE PROJECT

The project was divided into two phases. They are as follows:-

Phase-1- Developing model using ETABS.Phase-2- Analysis of reinforced concrete frames for static loads (dead, live, wind and load combinations) and dynamic load (Earth quake load-Spectrum cas-es).Inferences from the of Etabs Model:

A.Geometrical Configuration of the Tower:(i)No of storey: (2 Basements + Stilt +31 upper floors)(ii)Floor Height in m: (Basement 2 is resting on Foundation system, Basement 1=3.65,GF=4.4,First Floor=3.25,Typical floor 3.2,LMR and SHR=2.785 )(iii)No of lift: 3(iv)No of staircase :2 (v)Total height of structure: 113.285m till LMR roofHeight of building till terrace = 110.5mWidth of building = 21.79mLength of building = 25.18m

(vi)Height to Width ratio of building: 5.071(vii)Length to Width ratio of building: 1.155B.Structural Analysis and Design:(i)Structural Analysis Software: ETABS 9.7.2 Version(ii)Structural System: SMRF(iii)Foundation System: Raft foundation for entire tower(iv)Loading parameters:(a)Dead load: Self weight of slab + wall load + floor finishes(b)Live load: For Living areas -2KN/M2 For Balconies, Corridors, Staircases-3KN/M2(c) Seismic Load: As per IS 1893:2002(i) Zone Factor (Z): 0.36 for zone V(ii) Importance Factor (I): 1.0(iii) Soil type: 2.0

(iv) Fundamental Time Period (Tx/y):

Height of building till Terrace (h) = 110.5 Tx= (0.075 x h^0.75) = 2.556 sec

Ty= (0.075 x h^0.75) = 2.556 sec

(v)Response Reduction Factor (R):5 (for SMRF R is 5)

(vi)Seismic Coefficient (Ah x/y): X=0.0192 (Refer Page no. 1 of Appendix 1) Y=0.0192 (Refer Page no. 2 of Appendix 1)

(Vii) Seismic Weight: 325257.41kN. (Refer Page no. 1 of Appendix 1)

(viii) Base shears Vibe x/y: Vbx=6230.28KN ( Refer Page no. 1 of Appendix 1) Vby=6230.28KN ( Refer Page no. 2 of Appendix 1)

(ix) Damping: 5% ( Since it is a concrete structure)(V) Seismic Analysis Method: Response Spectrum Method.(a)No. of modes considered: 20 ( with 20 nos of modes, modal mass participating ratio is more than 90%,Refer Table 1)

(b)Modal Mass participation: First mode: 73% (Refer Table 1) Second mode: 18.2% (Refer Table 1) (c)Scale Factor i. Along X- direction: 1.4837 (Refer Appendix 3) ii. Along Y- direction: 1.6158 (Refer Appendix 3) (Vi) Total Deflection of Building: with fundamental time periodi.Along X direction: 110.81 mm (Refer for Point 595 of Table 2) < 442mm permissible(Permissible deflection = Span/250(=442mm) as per clause 23.2 of IS: 456-2000)ii.Along Y direction: 129.56mm (Refer for Point 53 of Table 2) < 442mm per-missible(Permissible deflection = Span/250(=442mm) as per clause 23.2 of IS: 456-2000)(Vii) Inter story Deflection (Storey Drift):With Fundamental Time period: 0.001467

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International Journal of Research and Innovation (IJRI)

prone regions are far from being solved. However in present time we have new regulations in place for construction that greatly contribute to earthquake disaster mitigation and are being in applied in ac-cordance with world practice. [8]* [4]*

In the regulations adopted for implementation in India the following factors have been found to be critically important in the design and construction of seismic resistant buildings:

Sites selection for construction that are the most favorable in terms of the frequency of occurrence and the likely severity of ground shaking and ground failure; High quality of construction to be provided con-forming to related IS codes such as IS1893, IS 13920 to ensure good performance during future earthquakes.To implement the design of building elements and joints between them in accordance with analysis .i.e. ductility design should be done.structural-spatial solutions should be applied that provide symmetry and regularity in the distribution of mass and stiffness in plan and in elevation.Whereas such the situations demands irregularity maximum effort should be given to done away with the harmful effects like that of SHORT COLUMN EFFECT

Researchers indicate that compliance with the above-mentioned requirements will contribute sig-nificantly to disaster mitigation, regardless of the intensity of the seismic loads and specific features of the earthquakes. These modifications in con-struction and design can be introduced which as a result has increase seismic reliability of the build-ings and seismic safety for human life.

References:-

[1].Murthy C.V.R, Learning earthquake design[2]Agrawal, Shrikhande Mansih, earth quake resist-ant design of structures[3]IS: 456:2000, Plain and Reinforced code of prac-tice.[4]IS: 1893(Part-1):2002, Criteria for earth quake resistant design of structure.[5]IS: 13920:1993, Ductile detailing of RCC struc-ture subjected to earth quake force.[6]SP:16,Design Aid for Reinforced concrete to IS:456:2000.[7]Ramamurtham,Theory of structures[8] Ashimbayev M.U., Itskov I.E., Lobodryga T.D.,living with natural and technological hazards, topic a.2: reducing vulnerabilities in existing build-ing and lifelines

Author:

D.Ramarao student atAurora s scientific and technological and ResearchAcademy,Hyderabad, India.

K. Mythili M.Tech(structural engg)Asso.Professor atAurora's scientific and technological and ResearchAcademy,Hyderabad, India.

G.Venkat RatnamAsso.ProfessorAurora's scientific and technological and Research

Academy,Hyderabad, India.

Abstract