Science Teaching Kit for Senior Secondary Curriculum
Force and Motion
Model Making
Workshop —
Structure of Tall
Buildings and Towers
[Student Notes]
Organizer
Sponsor
Research Team
Preamble
Learning plan
i
Lesson 1 : Model Making Workshop - Structure of Tall Buildings and Towers
1.1 Introduction to Tall Buildings
1.2 Loads and Forces on Buildings
01
02
1.2.1 Vertical Forces
02
1.2.2 Horizontal Forces
02
1.2.3 Internal Forces
02
Exercise: Forces on the Structure
1.3 Typical Structural Systems in Tall Buildings
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04
Project Brief on Tower-Making Workshop
06
Summary, Key words and Further reading
07
Disclaimer
Create Hong Kong of the Government of the Hong Kong Special Administrative Region provides funding support to the project only, and does not otherwise take part
in the project. Any opinions, findings, conclusions or recommendations expressed in these materials/events (or by members of the project team) do not reflect the
views of the Government of the Hong Kong Special Administrative Region.
© 2012 Hong Kong Institute of Architects
Science | Model Making Workshop — Structure of Tall Buildings and Towers
Contents
Topic 03
Model Making Workshop —
Structure of Tall Buildings and Towers
Major teaching areas
Interdisciplinary
Interdisciplinaryteaching
teachingareas
areas
Physics: Chapter II Force and Motion
Design
Designand
andApplied
AppliedTechnology
Technology
•• Strand
Strand1 1Design
Designand
andInnovation
Innovation
Force and motion
••
Strand
Strand2 2Technological
TechnologicalPrinciples
Principles
Related teaching areas
Physics: Chapter X Investigative Study in Physics
Learning objectives
•
To understand the forces acting on a stable structure
•
To learn the major structural systems for buildings
•
To apply new knowledge in a hands-on exercise
Learning plan
Lesson
Lesson 1
Contents
•
1.1
Introduction to tall buildings
Model Making Workshop
— Structure of Tall
Buildings and Towers
•
1.2
Explanation of the forces that act on buildings
•
Exercise Understanding of internal and shear forces, structural elements,
and the relationship between action and reaction
•
1.3
Examples of typical structural systems for high-rise buildings
•
Project
Brief and assessment methods for tower-making workshop
Science | Model Making Workshop — Structure of Tall Buildings and Towers
•
i
Lesson 1
Model Making Workshop —
Structure of Tall Buildings and Towers
1.1 Introduction to Tall Buildings
Tall buildings are symbolic elements within any city, carrying
significant political, social, cultural and even religious meanings.
Today cities compete to produce the tallest building in the world as
a way of showcasing financial and economic power. Understanding
the structures of these buildings, and how they support themselves
as well as the loads imposed on them by the environment, is a
fascinating way to see the real-life applications of physics.
p The Eiffel Tower is a 320-m-high steel
structure that was completed in 1889 as the
entrance arch for that year’s World’s Fair.
u The 36-storey Equitable
Building in New York was
completed in 1915. Its
architect, Ernest R. Graham,
used a Neoclassical style
despite the building’s
modernity: it was the first
building equipped with
elevators in New York.
t The modernist Wainwright
Building in St. Louis was
completed in 1891 by architects
Dankmar Adler & Louis Sullivan.
Its 10 storeys are supported by
an early steel framing system.
Science | Model Making Workshop — Structure of Tall Buildings and Towers
p The Leaning Tower of Pisa (55.86 m)
was built in 1372, using marble stone in
a Romanesque style. Its current leaning
appearance is due to sub-soil settlement.
t The 90-m-high Royal Liver
Building in Liverpool was one of
the first concrete buildings in the
world. It was completed in 1911
after a Neoclassical design by
Walter A. Thomas.
© Chowells - Wikipedia User
01
1.2 Loads and Forces on Buildings
The statics of a building deal with its structural stability.
According to Newton’s First Law, when an object is in
equilibrium, the sum of all forces equals zero.
Dead loads
e.g. Weight of the
building
Dead Load
Source:
Nature:
Live Load
Source:
Environmental Loads
e.g. Wind
Nature:
Environmental Load
Source:
Nature:.
1.2.1 Vertical Forces
p Live loads, dead loads and environmental
loads are the three major types of forces
on the Bank of China Tower. The loads are
transferred to the ground via columns and
pilings.
Compressive force
Vertical loads are transferred from the floors to the columns
and walls, and eventually to the soil or underground. At times,
environmental loads also act vertically.
Science | Model Making Workshop — Structure of Tall Buildings and Towers
Live loads
e.g. Weight of
people in the
building
1.2.2 Horizontal Forces
In architecture the horizontal forces on the building are called
shear forces, which may be resisted by adding cross bracing or
shear walls.
Tensile force
1.2.3 Internal Forces
The internal strength of the entire structure must be equal
to or larger than the total forces applied on the building in
order to stay in equilibrium. The ability to withstand all forces
depends on the structural component’s dimensions and the
solidity and elasticity of the material. Internal forces include
compressive force, tensile force, and torque.
Torque
p Internal forces in a structural element
02
[Exercise]
Forces on the structure
1
Illustrate the action and reaction pairs, and distinguish dead loads and live loads acting on the following structure. Assume the weight of the mass is FA and the weight of each building block is FB , and the structure is in equilibrium.
Can you identify the internal forces acting on each piece of the structure? What paths do they take?
Loads
3
How would you modify the below structure to resist shear force?
Science | Model Making Workshop — Structure of Tall Buildings and Towers
2
Shear Force
03
1.3 Typical Structural Systems in Tall Buildings
Outrigger
Core
Columns
Core and outrigger structure
The International Commerce Centre is built using a ‘Core
and Outrigger’ concept. The core at the centre of the
building bears most of the vertical load, while columns
at the perimeter carry less weight and are thus smaller
in dimension. Loads are transferred to the core through
steel outriggers that balance the lateral forces on the
whole building.
p Outrigger connecting the core and the columns
Columns at the perimeter
carry less weight.
Weight is centralised to
the core.
Outriggers help balancing
lateral forces.
p Plan of International Commerce Centre
Steel
Steel is a common construction material for tall buildings because it has good
performance in withstanding compressive and tensile forces, as opposed
to concrete’s low tensile strength in compression. Steel bars can be used
to reinforce concrete to add extra structural performance. However, steel is
relatively weak in fire-resistance.
The Bank of China Tower is a steel trussed-tube structure. The whole building
acts as a single tubular truss, with the diagonals wrapping the building to
transfer loads.
p Bank of China Tower
Science | Model Making Workshop — Structure of Tall Buildings and Towers
p Installation of outriggers at the International Commerce
Centre © Raymond Wong
04
result
External
force
External
force
result
External
force
Co
m
pr
es
sio
n
External
force
m
Co
Tension
Truss
Trusses are a very common structural
element in architecture. Steel
members are joined together into
triangular shapes, which are very
strong and able to resist external
forces. When joined together, these
triangles can form large truss systems
that can span long distances.
n
io
s
es
pr
Science | Model Making Workshop — Structure of Tall Buildings and Towers
q Common types of truss
© Structural Building Components Association
05
Project
Model Making Workshop — Tower
The class will be divided into groups of four to five students. Each group is required to build a tower that should be:
• structurally stable and aesthetically pleasing
• tall
• lightweight
• resistant to horizontal forces
• able to support a heavy load
Submit a laboratory group report after the workshop.
needed
Sketching papers and pencil
Scissors, cutters, tape, glue
Different weights (10 g/ 50 g/ 100 g/ 500 g/ 1 kg)
Weight scale
Measuring tape
Electric fans
Suggested materials
• Cardboard
• Bamboo sticks
• Recycled cans
• Recycled plastic bottles
• Fishing line
Assessment criterias:
Tests
Structural stability (20)
Aesthetics (10)
Height (20)
Weight-height ratio (20)
Resistance to wind (10)
Load supporting (20)
p Using rope to join the components
Descriptions
The tower should be free-standing without external supports.
The teacher will judge the beauty of the tower and will give a score.
Measure the height of the tower from the ground to the highest point.
The tallest tower gets the highest score.
Weigh the tower and find out the weight-height ratio. The tower with
the smallest ratio will get the highest score.
R=
Your Score
Science | Model Making Workshop — Structure of Tall Buildings and Towers
Tools
• • • • • • W
H
Blow the tower from the side with an electric fan. The tower that does
not fall will get the highest score.
Test the maximum weight that the tower can support. The weight
needs to be placed above the ground. Students should be able to
explain how load is transferred to the ground.
Total score
06
Summary
1.
2.
3.
4.
Although humans have long attempted to build tall structures, skyscrapers began to appear in our cities in the late 19th century as a result of technological breakthroughs in building materials and methods, including reinforced concrete, steel, and elevators.
Buildings bear three types of loads: dead loads, live loads and environmental loads
All loads are resolved into vertical and horizontal forces on the structure.
Typical structural systems used in tall buildings include core and outrigger structures, steel frames and trusses.
Key words
Further reading
1. Foster, Jack Stroud, Raymond Harington, and Roger Greeno. Structure and Fabric. 7th ed. Harlow: Pearson Prentice Hall, 2007.
2. Brotrueck, Tanja, Basic: Roof construction. Basel: Birhaeuser, 2007.
Organizer
Sponsor
Research Team
Science | Model Making Workshop — Structure of Tall Buildings and Towers
High-rise buildings
Skyscraper
Tower
Structure
Force
Equilibrium