Tube Frame Structures:An overview

TUBE FRAME STRUCTURES

SUBMITTED BYZAFRIN MOHAMEDROLL.NO:77S7 CE B

GUIDED BYMrs. VARNA K THANKAPPANASSISTANT PROFESSORIIET,NELLIKUZI

CONTENTS• Introduction• Need for high rise buildings• Different configurations• Advantages• Disadvantages• Brief explanation of shear lag• Conclusion• References

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CIVIL DEPT.IIET NELLIKUZHI

INTRODUCTION

• Introduced by Fazalur Khan,Dhaka Bangladesh

• Hollow cantilever perpendicular to the ground

• Buildings in excess of 40 stories • A 43-story Khan-designed De-

Witt Chestnut Apartment in Chicago

• Steel, concrete, or composite construction


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De-Witt Chestnut Apartment,Chicago

Need for tall structure• Increase in building height• Slenderness• Building weight reduction• Limited availability of land• Rapid increase in cost of

land

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CONCEPT OF TUBULAR SYSTEM

• Design of strength, rigid and stable structures

• Largely economic solution• Building designed for resisting lateral

loads• Hollow cantilever perpendicular to

ground• Incarnation of the tubes• Exterior-Columns and beams forms a

rigid frame • Interior-simply framed for gravity loads • 50% of windows on exterior wall surface

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Learning the structural behaviour

Defining tube frame

• Predict the structural behavior• Replace 3D system by

equivalent plane frame• Analysed by conventional

methods• Comparison of results- 15 story

Perspex model of the building• Deciding the type of

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Configuration of Tubes

• Framed or box tube• Braced tube• Tube in tube• Bundled tube

The Framed Tube• The frames consist of closely spaced

columns, 2 - 4 m between centers, joined by

deep girder .• Act as perforated chimney or stack• Lateral resistance is by the stiff

moment resisting frames• Gravity load shared by interior and

exterior columns• Appropriate for buildings having 40-

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Tube frame structures


Cont..• Grid like facade structures and is

repetious• Use of prefabrication possible• Larger distance of exterior column

from NA resists bending moment• Economically attractive and possess

torsional rigidity• Greater flexibility in space planning• A well known example-World Trade

Centre

CASE STUDY OF WORLD TRADE CENTRE



• Architect:-Minoru Yamasaki

• 110 story tower• 415m in height• 50,000

employees and 80,000 visitors daily

• Twin tower in diagonal juxtaposition

Cont…• vertical extrusions of square plans• The framed tube consist of 56 box

steel columns joint by moment resisting connections

• The overall dimensions of framed tube column are constant

• Wall thickness increases from top to bottom to increse response to loads





Braced Tube Structures• Further improvement of framed tube• Cross bracing frame with x braces

over many stories-(fig)• First used in John Hancock building,

Chicago-(fig)• Diagonals of a braced tube connect

columns at each intersections• Shear lag is virtually eliminated• Spacing for columns are increased• Depth of girders are small

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CIVIL DEPT.IIET NELLIKUZHIJohn Hancock Building, Chicago

Cont…

• Large sized windows are allowed• Braces transfer axial load from

highly stressed column to low stressed column

• Hence eliminates difference between load stress

• Large scope of architecture .uses a structural-architectural concept



Tube-in Tube Structures• Consist of outer framed tube together

with an internal elevator and a service core

• Inner tube would be braced frames• Outer tube has greater structural

depth, so plays dominant role• Outer tube-hull (fig)• Inner tube –core• Inner tube holds elevator and other

services• Another tube around the exterior

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Cont…

• 780 third avanue,Metro Manhattan office space is the first work

• Concrete shear wall for bracing in the hull(fig)

• Off centre core allowing column free interiors

• Accuracy,reliability and simplicity are verified




TUBE FRAME STRUCTUREScore

hull



Metro Manhattan Office Space

Bundled Tube

• Consists of multiple tubes instead of 1.

• Several tubes tied up to resist lateral forces

• Interior columns on the parameters of the tube (fig)

• Willis Tower, Burj Khalifa are best examples



Cont..• Highly efficient

in economic terms

• Bundled together in different sorts of grouping

• Not necesserily box shaped



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Willis Tower



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Burj Khalifa

Advantages of TFS• Allows greater flexibility in planning

of interior space • Regularity in the column schedule

allows off-site fabrication and welding • maximum advantage is taken of the

total width of the building to resist overturning moment

• Identical framing for all floors• When well designed, tubular forms

uses same amount of material as in a half large structure



Criticism of TFS• Reduces the size of the opening

in the building .• At greater heights,view of outer

world is obstructed• Shear lag• Linear distribution of axial forces

across flange and web varies• closely spaced columns are not

encouraged and undesirable



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Shear lag

• Occurrence of non uniform axial stress distribution

Features:-• Positive shear lag• Negative shear lag• Negative shear lag-buckling

on the compression side &cracking on tension side.



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Conclusion• The provision of adequate, stiffness,

particularly lateral stiffness is a major consideration In the design of a tall building hence TFS are engineers favorite

• But structural cost of the TFS may be high with respect to conventional shear wall structure

• so necessary to do research for cost comparison between TFS and conventional shear wall



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References1. Er. Nahant Rana,et.al.” Structural Forms Systems for Tall Building

Structures,SSRJ”, International Journal Of Civil Engineering (SSRG IJCE), September 2014volume issued4

2. Hardin J. Patel,et,al. “Braced Tube Structural System: A review” International Journal of Scientific & Engineering Research, December-2015, , Volume 6, Issue 12.

3. R. Mahjoub,et,al, “Simple Analysis of Tube Frame System of Tall Building by Using Deformation Functions”. Australian Journal of Basic and Applied Sciences, February 2011. [324-332]

4. Reza Mahjoub,et.al“Analysis of Tube Frame System of Tall Building by Using of Deformation Functions”. Australian Journal of Basic and Applied Sciences, 5(8): 1475-1482, 2011.

5. Sharadrao Patil,et.al, “Shear Lag in Tube Structures”. IJISET - International Journal of Innovative Science, Engineering & Technology, March (2015), Vol. 2 Issue 3,



Tube Frame Structures:An overview

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