ARCHITECTURE, ANALYSIS AND DESIGN OF SKYSCRAPER

Architecture, Analysis &Design of Skyscraper

Under the esteemed guidance of

Mr. Botsa Srinivasa Rao

M. Tech, Structural Engineering, IIT Guwahati

Lecturer, RGUKT – Nuzvid

By

N091918 – M Venu

N100246 – K N S Varsha

N100505 – M Ravi Teja

N100603 – Ch Chandra Kala

N100654 – J L Harika(Civil Engineering, Batch 2016)

Contents

o Introduction

o Software

o Structural Systems

o Planning

o Architecture

o Loads

o Shear wall

o Modelling

o Analysis

25-Apr-16 B. Tech Project - RGUKT Nuzvid 2

o Design

o Results

o Conclusion

o Future scope

o References

Introduction

• Scarcity of land

• Leaping demand for business and residential space

• Thriving economies and booming populations

• Broad casting and research facilities

• Advancements and innovations in structural systems

• Desire for aesthetics

• Tallness of building is more often relative

• Skyscrapers are in general a height greater than 150m


Introduction (Contd.)

• ‘skyscraper’ was coined in 1880s

• Steel has made it all possible

• 1st ever tall building

• Home Insurance Building in Chicago

• Height - 42 m.

• Greater than 150 m as per CTBUH

• Super tall (>300 m)

• Mega tall (>600 m)

• Greater than 15 m as per NBC

• Greater than 21 m as per US General Laws


Softwares

• ETABS (Extended Three dimensional Analysis of Building

Structures) – Computers and Structure Inc.

• Revit Architecture - Autodesk

• AutoCAD – Autodesk

• Pile - Oasys

• MS Excel - Microsoft


Components of tall buildings

• Floor systems

• Gravity load resisting systems

• Lateral load resisting systems

• Connections

• Damping systems


Structural systems

• Knowing the skeleton


Fig.1 Evolution of Structural Systems

Structural systems (Contd.)

• Knowing the interlinks


Fig.2 Classification of Structural Systems


• Moment resisting frames

• Shear frames

• Frame with shear resisting trusses – Interacting

• End channel framed tube with interior trusses – Partial tube

• Exterior framed tube or bundled tube

• Exterior diagonalized tube


Fig.3 Framed tube

Preferred structural system

• Tube in Tube (Hull and Core)

• Similar to Hollow Cantilever beam

• More column free space

• Lateral stiffness by the perimeter frame

• Maximum bending rigidity

• Flange frames normal to the wind carry axial loads

• Web frames parallel to the wind carry shear



Fig.4 Unfolded plane frame

Planning


• Core covers 25% of the total built up area

• Built up area: 13, 600 sq. m

• Core : 3,400 sq. m

Fig.5 Proposed layout of the skyscraper

Planning (Contd.)

• Built up area : 936 sq. m

• Core area: 234 sq. m

• Minimum built up area: 800 sq. m


Fig.6 Scaled layout – Tube in tube

Planning (Contd.)

• Flange planes – overturning moment

• Web planes – lateral shear force


Fig.7 Total layout of the skyscraper

Planning (Contd.)

Child Bed rooms

M Bed room

M Bed room M Bed room

M Bed room

Child Bed rooms

Kitchen

Child Bed rooms Child Bed rooms

Kitchen

Core with elevators

Dining

Dining

Fig.8 Floor plan of the residential stories

Planning (Contd.)


Conference room

Working cabins

Manager 1 Manager 2

Head

Fig.9 Floor plans for the office floors

Planning (Contd.)


Terrace area

Res

taura

nt

Res

taura

nt

Elevators Elevators

Spine

Fig.10 Floor plans for the restaurant

Architecture

• Overall shape – based upon drag coefficient

• Vertex of the triangle facing the wind

• Two vertices resisting earthquake

• Opening reduces the wind forces

• Central spine for the stiffening

• 320 mm φ hollow circular steel – spine

• 12 elevators

• Higher weightage for dead load


Fig.11 Architectural view

Architecture (Contd.)

• Visible opening in the neglected wind direction


Fig.12 Front view of the skyscraper


• Front yard and rear yards – 10 m. each

• Side yard – 6 m

• Total plot area: 2674 sq. m


Fig.13 Front perspective


• Front door – 1.5 m each


Fig.14 Entrance through revolving doors


• Bed room – 23. 88 sq. m

• Minimum – 12 sq. m


Fig.15 Bed room


• Area: 130. 81 sq. m


Fig.16 Conference room


• Terrace area: 695 sq. m


Fig.17 Sky line view


• Area of each restaurant: 82.50 sq. m


Fig.18 Inner view of restaurant


• Analogous to isometric view


Fig.19 Perspective view

Loads• Dead load

• Live load

• Earthquake load

• Wind load (Arrow indicates the direction of wind)


𝐶𝑑 = 1.2 𝐶𝑑 = 1.4

𝐶𝑑 = 2.0 𝐶𝑑 = 2.2

𝐶𝑑 = 2.2 𝐶𝑑 = 1.5

Fig.20 Drag coefficients for different shapes

Loads (Contd.)

• Seismic zone – III

• Critical wind and MCE will not occur simultaneously

• Considering equivalent static design base shear


S. No Parameter Magnitude/Description

1. Basic Wind speed (Vb) 50 m/sec

2. Terrain Category 4

3. Class of the structure C

4. TopographyNumerous large high closely

spaced obstructions

5. Life of the structure(N) 100 yrs.

6. Wind zone 5

Table.1 Wind data for the skyscraper

Shear wall


Fig.21 Models – 1,2,3,4

Shear wall (Contd.)


Fig. 22 Model - 5

Shear wall (Contd.)


Fig.23 Maximum Joint displacements under gravity loading

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 8

Sto

rey N

o

Joint displacement (mm)

Joint displacements for gravity loading

without shear wall

Shear wall at Core

Shear wall at edges

Shear wall at Corners

At core without beams

Shear wall (Contd.)


Fig. 24 Applied Lateral loading the joints of floors

0 100 200 300 400 500

Story 6

Story 5

Story 4

Story 3

Story 2

Story 1

Base

Lateral load onto the floors

Lateral load(kN)

Shear wall (Contd.)


Fig.25 Maximum Joint displacements under Gravity loading + Lateral loading

0

1

2

3

4

5

6

7

0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 255

Sto

rey N

o

Displacement(mm)

With Lateral loading

Shear wall (Contd.)


Efficiency of the models

With Gravity loading alone,

Model 5 = Model 2 > Model 4 = Model 3 > Model 1

With Gravity loading + Lateral loading

Model 5 ≈ Model 2 > Model 4 > Model 3 > Model 1

Modelling

• Grid based modelling of the structure

• Columns for the hull

• Connecting through beams

• Core with Shear Walls

• Replicate up to 50 stories

• Defining material and section properties

• Assigning material and section properties

• Defining load cases, patterns and combinations

• Applying the loads

• Setting load cases to run, analysis and design


Modelling (Contd.)


Fig.26 Grid and Columns for the hull

Fig.27 3 D view of story 1

Modelling (Contd.)


Fig.28 Evolution of the modelling

• Step-by-step models for resisting the loads

Analysis (Contd.)


Fig.29 Auto lateral loads due to (a) EQx ,(b) WLx

• More the weight of floor, more it contributes to lateral load.

Analysis

• 40 columns and 300 beams

• In the columns

• Critical combination – 1.5(DL+FFL+EQy)

• Max. axial force (P) = 86,769.8 kN; Column in Story 1

• Max. moment (M2) = 5717.6 kN – m; Column in story 8

• In the beams

• Critical combination – 1.5(DL+FFL-EQx)

• Beam beside the core in story 15

• Max. V2 = 2595.34 kN

• Max. M3 = 6265.50 kN-m


Analysis (Contd.)


Fig.30 Drifts for diaphragm (a) without outriggers ,(b) with outriggers

• Outrigger truss – W 40 X 593 of Fe 415

• Location: Every one – third height

Analysis (Contd.)


• Maximum sway: 1 in 357

• Range: 1 in 800 - 1 in 200

Fig.31 Displacements

Analysis (Contd.)


• Maximum story drift – 0.4 % (IS 1893, part 1: 2002)

• Obtained story drift – 0.28 %

Fig.32 Auto lateral loads due to EQy

Analysis (Contd.)


Fig.33 Story shears and overturning moment

• Base shear force – 93, 000 kN

• Overturning moment (x) – 46 X 106 kN-m

• Overturning moment (y) – 65 X 106 kN-m

Analysis (Contd.)


• Modal analysis – deflected shape and direction

• 12 modes – may vary based on time period

• Arbitrary scaling

• Period of vibration decreases with increase in mode number

Fig.34 All the mode shapes

Analysis (Contd.)


Fig.35 Non-linear static analysis- (a) Hinge formation,(b) static pushover curve

• Static excitation and non – linear response

• Displacement control

Design

• Beam design – IS 456: 2000

• Reinforcement – 1.99 %


Fig.36 Location of critical beams

• Composite column design

• Embedded I section: W 40 X 593


Design (Contd.)

Fig.37 Beam cross-section

1000mm X 1000mm

Fig.38 Colum cross-section

1500mm X 1500mm

• 50 mm φ longitudinal rebars

• Symmetry reduces crookedness

• Torsional moment – 0.0094 kN – m (negligible for design)

• Composite column design

• Code: AISC 360 -10


Design (Contd.)

Fig.39 Column capacity ratios

• Max. vertical load from an isolated column = 86,770 kN


Design of pile

Dep

th (

m)

• Safety factor – 2.5

Fig.40 (a) Soil profile, (b) Design in Oasys Pile


Conclusions

• Architectural views are drawn

• Reduction in torsional moment because of symmetry

• Lateral sway is 44% less compared with the existing ones

• Lateral drift is 0.28% only

• Drift is 86% lesser compared to that of threat to human safety

• Comprehensive Linear static analysis

• Composite Columns are designed

• Isolated pile is designed

• Tube-in-tube system is well appreciated


Future scope

• Increase in base dimension and height of skyscraper

• Employing work station for further analyses

• Non-linear Static analysis by hinge formation

• Non-linear Dynamic analysis for real time response

• Max. displacement during the disasters can be identified

• Design of pile cap over the piles and/or spun piles

References• Aainawala M. S, Dr. Pajgade P. S (2014), “Design of Multistoried R.C.C. Buildings with

and without Shear Walls”, International Journal of Engineering Sciences and Research

Technology, ISSN 2277-9655, Vol.3 (7).

• Taranath B. S (1988), “Structural Analysis and Design of Tall Buildings”, McGraw – Hill

Publishing Company Ltd., ISBN 0-07-062878-5.

• Ali M, Moon K. S (2007), “Structural Developments in Tall Buildings: Current Trends

and Future Prospects”, Architectural Science Review, Vol. 50.3, pp. 2015-223.

• Wagh S.A, Waghe U. P (2014), “Comparative Study of R.C.C and Steel Concrete

Composite Structures”, Int. Journal of Engineering Research and Applications, Vol.4,

Issue 4, pp.369-376.

• David Spires, Arora J.S (1990), “Optimal Design of Tall RC-Framed Tube Buildings”,

Journal of Structural Engineering, ASCE, Vol. 116, No.4.

• Aminmansour A (2010), “Integrated Design and Construction of Tall Buildings”, Journal

of Architectural Engineering, ASCE, Vol. 53.

• Alaghmandan M, Elnimeiri M (2013), “Reducing impact of wind on tall buildings through

design and aerodynamic modifications”, ASCE, pp. 847 -856.

• Chang P.C, Foutch D. A (1984), “Static and dynamic modeling and analysis of tube

frames”, Journal of Structural Engineering, ASCE, Vol.110, No.12, pp.2955-2975.

• Baker W. F et al. (2009),”The Challenges in Designing the World’s Tallest Structure: The

Burj Dubai Tower”, Structures Congress, ASCE, pp. 1471-1480.



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ARCHITECTURE, ANALYSIS AND DESIGN OF SKYSCRAPER