Transcript Introduction and Building Loads

Construction
and
Building Loads
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Construction Standards
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2. Construction Technologies
Central Concepts: The construction process is a series of actions taken to build a
structure, including preparing a site, setting a foundation, erecting a structure, installing
utilities, and finishing a site. Various materials, processes, and systems are used to build
structures. Students should demonstrate and apply the concepts of construction
technology through building and constructing either full-size models or scale models
using various materials commonly used in construction. Students should demonstrate
the ability to use the engineering design process to solve a problem or meet a challenge
in construction technology.
2.1
Identify and explain the engineering properties of materials used in
structures (e.g., elasticity, plasticity, R value, density, strength).
2.2
Distinguish among tension, compression, shear, and torsion, and explain how
they relate to the selection of materials in structures.
2.3
Explain Bernoulli’s principle and its effect on structures such as buildings and
bridges.
2.4
Calculate the resultant force(s) for a combination of live loads and dead
loads.
2.5
Identify and demonstrate the safe and proper use of common hand tools, power
tools, and measurement devices used in construction.
2.6
Recognize the purposes of zoning laws and building codes in the design and
use of structures.
Changing Construction
Development
• Materials – properties of material change
– Early Timber & Masonry ~ limit to 5 stories
– Wrought Iron & Steel in mid 1880s ~ I beams etc allowed
longer spans such as bridge spans.
– Structural Concrete after 1900 ~ rebar – reinforcement bar
along with structural steel allows for taller building
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The Elevator
– Became popular in late 1850’s with
of the safety brake by Elisha Otis
– Made upper stories attractive to rent
– Made tall buildings financially viable
Construction Technology
– More efficient equipment – fluid energy
(heavy equipment, nail guns)
– Improved methods – balloon vs platform
use of trusses ( and materials)
– Increase Speed
Types of Structures
Types of Construction Projects
Buildings
Residential buildings, commercial
buildings, and industrial buildings.
-May include monuments, cultural and
government buildings, transportation terminals,
sports arenas and exhibition centers, and
agricultural buildings.
Heavy
Engineering
Structures
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Transportation, communication, and
production structures.
-Roadways, bridges, antenna towers, refineries,
and dams.
Designs Differences
Office vs Residential
• Office/Commercial buildings
– Large entrances and open spaces means long building spans
– Reconfigurable space floating partitions (large column, open areas)
• Residential buildings
– Partitions are frequent and the same from story to story to
form load bearing walls
– Shorter spans – size of structural members smaller
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Loading
• Buildings are designed to carry all
gravity loads and lateral loads to be
seen during construction and
service.
• Must consider sequential loading
(particularly during construction)
• Types of Loading:
– Dead (Weight of structure & fixtures)
– Live (Occupancy Loads)
• Impact (hammering, marching on a
bridge, machines that have vibrations)
• Snow
• Wind
• Temperature (expanding and shrinking)
• Seismic
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Dead Load
• Dead loads are the
weights of all items
permanently attached
to the structure.
• Dead loads in a
residential structure
are usually calculated
at 20 lbs psf (per
square foot).
• Partitions (interior
walls) are usually 20
lbs psf.
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Live Loads
• Live loads are any
loads that are not
permanently attached
to the structure.
• Live loads in a
residential structure
generally are expected
to be 40 lbs psf (per
square foot).
What do the Two white arrows represent?
What do the three red arrows represent?
Wind, Snow, People, Furniture all live loads.
What does the blue arrow represent?
Attic storage which is also a live load.
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Forces are equal and opposite
so the white arrows indicate an
upward force on the bottom of
the footing to support the
house.
Tributary Areas
• Useful for determining member forces due
to UNIFORMLY APPLIED loads (dead,
live, pressure, etc....) on SIMPLY
SUPPORTED members.
• Structural analysis theory to find the “path”
that loads take as they “find their way”
down to the foundation through the
structural members.
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Tributary Area On A Floor
• Applied load
is uniformly
distributed.
Each member
supports the load and
transfers it to a larger
member.
Tributary area on the
post or lally column.
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DL Calculation on a floor with a
ceiling below.
Floor Dead Load
1/4” Linoleum (w/glue)
1.8 psf
1/2” Underlayment (plywood)
2.0 psf
5/8” Plywood (sub floor)
2.2 psf
2x12 @ 16” O.C. (on center)
3.5 psf
5/8” Gypsum Board (Sheetrock)
3.2 psf
Metal suspended ceiling
2.1 psf
Misc.
1.5 psf
Total
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16.3 psf
DL Roof Calculation
Roof Dead Load
Asphalt Shingles
5/8" Ply wood
2x12 @ 16" O.C.
Insulation
5/8" GWB
Suspended Ceiling
Misc
Total
12
Slope/12
6
6
6
6
6
0
Flat
2.5
1.8
3.3
3.6
2.8
1.8
Slope f act
Adjusted
1.12
2.8
1.12
2.0
1.12
3.7
1.12
4.0
1.12
3.1
1.00
1.8
1.5
19.0
psf
psf
psf
psf
psf
psf
psf
psf
Structural Forces
• Structural Forces
A force is a push or pull that transfers energy to an
object. Structural materials are subjected to both internal and
external forces and must be considered by engineers as they
design safe and lasting structures.
• Internal Forces
Internal forces are those that act within structural
materials. They are forces exerted by one part of a structure
onto another. The source or cause of internal forces may be
either internal or external. Examples of internal forces are
tension, compression, torsion, bending, and shear.
• External Forces (Load)
A load is an external force on a structure. It may be caused by
physical weight on a structure, or by environmental sources such
as wind, water, or temperature.
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Parts of a Structure
• Structural Member
Each individual part of a structure is called a
member.
• The attachment point of two or more members is
called the joint.
• Horizontal members are called beams, and are
built to withstand bending.
• Vertical members are called columns, and must
withstand compression.
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Compression
• Compression
A force that pushes or
squeezes is called
compression. A structural
material in compression
may be shortened or
crushed.
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Tension
• Tension
Tension is a force that
pulls or stretches.
Tensile Strength
The ability of a material
to withstand tension
without parting is called
tensile strength.
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Bending
• Bending
When a straight member
becomes curved, one side is
in tension while the other is
in compression. Engineers
must either prevent bending,
or select materials that can
perform well in both tension
and compression.
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Torsion
• Torsion
the twisting of a structural
member by the exertion of
forces to turn one end or part
about a longitudinal axis while
the other is held fast or turned
in the opposite direction
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Shear
• Shear
Shear is a force that
causes parts of a
material to slide past one
another in opposite
directions, usually in a
parallel manner. Shear
may also be described as
a sliding force.
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Constructing Buildings
(Gehl Co.)
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Zoning Laws
• What do zoning regulations do?
• Zoning regulations establish how the land
can be used, either for residential, industrial,
commercial, or recreational purposes.
• Designed to protect you, your neighbors,
and the community from undesirable, or
inappropriate, land uses and/or construction.
• They can protect property value by planning
for the future of the town and preventing a
business or industry from misuse of the
land.
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Building Codes
• Building Codes
Regulations established by a
local government describing
the minimum structural
requirements for buildings.
Specifications involve the
foundation, roofing,
plumbing, electrical, and
other matters of safety and
sanitation.
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End of show
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Constructing Buildings
Preparing the site
-choosing a location
-Check zoning & Building codes
-purchasing the land
- clearing
- grading
-leveling the site.
(Gehl Co.)
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Constructing Buildings
Setting The Foundation
-Two Parts of the foundation
- - Footing distributes the weight of
the structure on the ground.
- - Foundation wall Transfers the weight
of the structure to the footing.
-Types of foundations: T-foundation,
Slab & Pier
(Gehl Co.)
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Constructing Buildings
Building the Framework
- frame of a house is like a skeleton
- - Footing distributes the weight of
the structure on the ground.
- - Foundation wall Transfers the weight
of the structure to the footing.
-Types of foundations: T-foundation,
Slab & Pier
(Gehl Co.)
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