BURJ KHALIFA DESIGN BRIEF

The present article provides ready reference structural information about the world’s tallest structure Burj Khalifa. The main objective of article is to provide bench mark quantities for structural information for tall building.

	Project Type	:	Mixed Use Project ( Five Star Hotel, Office, Retail and Residential)
	Total Floor area	:	439,935m2
	Site Area	:	104,210m2
	Height	:	828m ( Concrete 606m Plus Steel  222m)
	Gross Floor area above Grade	:	312,400m2
	Floor Plate Size at Grade Level	:	3,065m2
	Floor Plate Size at Upper top	:	380 m2
	Floor Plate Size at Basement	:	35,300m2
	Structural Consultant	:	SOM
	Wind Engineering Consultant	:	RWDI Wind Tunnel Analysis Rigid Model Force Balance Tests Full Multi Degree of Freedom Aero-elastic Model
	Floor Geometry in Plan	:	Y Shaped (to reduce the wind forces on the tower, as well as to keep the structure Simple and foster constructability)
	Structural System	:	“Buttressed” Six Sided Central Core, Each wing, with its own high performance concrete core and perimeter columns, buttresses the others via a six-sided central core, or hexagonal hub
	Foundation	:	Pile Supported Raft
	Number of piles under tower	:	194
	Pile Diameter	:	1.5m
	Length of pile	:	43.0m
	Concrete Cube Strength for Pile	:	60MPa SCC ( Self Compacting Concrete)( Triple Blend 25% Fly Ash + 7% Micro silica + Portland Cement, Water Cement ratio 0.32)
	Pile Load Test	:	6000 t
	Working Design Capacity	:	3000 t
	Raft Thickness	:	3.7m
	Reinforcement Spacing	:	300 mm c/c­­­­
	Concrete Cube Strength for Raft	:	C50 Self Consolidating Concrete
	Super Structure
	Number of Outrigger Levels	:	5
	Concrete cube strength for Vertical Element (Reinforced Concrete Wall/column)	:	C80 ( at Base checked at 90 Days instead of 28 Days) – C60 (at Upper Level)
	Composition of Concrete for Vertical Elements	:	Portland Cement + Fly Ash
	Analysis Software and Model Size	:	ETABS (Version 8.4) , 73,500 Shells and 75,000 Nodes
	Reinforced Concrete Design Code	:	ACI 318-02
	Free Vibration Analysis Result 1st Mode, Lateral Side sway 2nd Mode, Lateral Side sway 5th Mode, Torsion Mode	: : :	11.3 sec 10.2 sec 4.3 sec
	Top Steel Portion ( Spire)	:	Diagonally braced lateral system
	Steel Design Code	:	AISC LRFD 1999
	Seismic Zone	:	Zone 2A ( Z = 0.15) as per UBC97
	Modulus of Elasticity of Concrete (Ec)for Core and Outrigger at Lower Portion at 90 Day	:	43,800MPa
	Walls and Columns optimized	:	Virtual Work Method
	Effect of Column Shortening	:	Perimeter columns were sized such that the self-weight gravity stress on the perimeter columns matched the stress on the interior corridor walls.
	Weight of Empty Building	:	500,000MT
	Quantity
	Concrete	:	330,000 m3
	Reinforcement Steel	:	39,000MT
	Glass used for Façade	:	103,000 m2
	Stainless Steel used for Cladding	:	15,500 m2
	Structural Steel for Top Spire	:	Approximately 4000MT

                                    

UBC97 and IBC/ASCE Seismic Load Comparision

Structural Dynamics - Interview Questions - Structural Engineers

Calculate natural frequency ( or fundamental time period) 

for following problems

UBC97 - Seismic Base Shear Calculation Procedure

UBC 97 Seismic Base Shear Calculation Steps are as follows

1. Seismic Zone Factor (Z)

Civil Engineering Softwares

3D Frame ( Steel and Concrete) General Purpose Software

1. SAP2000
2. STAAD Pro
3. ROBOT Structural Analysis
4. OASYS
5. ETABS ( 3D Building Analysis and Design Software)

Building Floor System

1. RC Slabs - SAFE
2. Post Tension Slabs - ADAPT PT, RAPT, RAM Concept
3. Metal Deck Composite FLoor - TATA Comflor
4. RoofDeck Analysis Software from TEDS

Finite Analysis Software (having Macro/command line and advance elements)

1. NISA
2. GT-Strudl
3. ANSYS
4. ADYNA

Bridge Analysis Software

1. SAP2000-Bridge
2. Sofistik
3. RM Bridge

Foundation Engineering Question

1. Broadly describe classification of piles 
2. Calculate Structural compression capacity of 1500mm diameter concerete (C40 Grade) pile
3. What % of Piles to be tested for Static Test, Dynamic Test, Integrity Test and Sonic Test
4. Describe initial load test of piles
5. Draw bending moment diagram for free and fixed head pile along length of pile under lateral load
6. Provide approximate relationship between safe bearing capacity and N ( standard penetration test N Value).
7. Provide approximate relationship between safe bearing capacity and undrained shear strength 
8. What is minimum c/c distance between piles for Driven Piles, Bored Piles and Mini piles
9. What is relationship between safe vertical load capacity and displacement and lateral capacity of pile
10. Write Terzaghi's soil bearing capacity formula
11. Classification of Granular (Non-cohesive) soil and Cohesive soil

Earthquake Resistant Design Interview Questions

Questions are taken from book - "Seismic Design of Building structures" By Michael Lindeburg and Majid Baradar

1. What is difference between stiffness and rigidity as used in seismic design?
2. What is difference between ductility and flexibility as used in seismic consideration?
3. What is ductility and ductility factor?
4. What is the natural period of a building? Describe Method A and Method B to compute natural time period described in UBC97?
5. What does the term redundancy means as it is used in the context of modern high rise buildings
6. What causes torsional shear?
7. What is negative torsional shear?
8. What is response spectrum?
9. Describe how base shear is calculated according to the UBC97 / IS 1893/IBC equation
10. What is the P - Delta effect?
11. What possible values can R take on for a moment resisting frame?
12. Describe different Vertical and plan irregularity in Building
13. Describe principle of seismic detailing in beam and column in moment frame?
14. Describe three principles of design of special moment frame
15.  Draw vertical distribution of seismic force along height of building