PREPARED BY :
NOR AZAH BINTI AZIZ
KOLEJ MATRIKULASI TEKNIKAL KEDAH
2.0 ANALYSIS AND DESIGN
2.2 STRUCTURAL ELEMENTS
Load Paths
•
The
load path
is simply the direction in
which each consecutive load will pass
through connected members.
•
The sequence commences at the highest point
of the structure working all the way down to
the footing system, ultimately transferring the total
load of the structure to the foundation.
Load Paths
•
Ultimately, the lowest structural member must
be strong enough to support all members above it.
•
This is why engineers often design the uppermost
members first and progressively work their way
down the structure following the load path.
RAFTER
PURLIN
GROUND SLAB
STUMP
FOUNDATION
COLUMN
ROOF BEAM
ELEVATED
SLAB
ROOF SHEET
GROUND BEAM
WALL
Load analysis distribution and path
Load Path Components in a Concrete
structure
•
Part of the load
path in a typical
multi

storey
reinforced concrete
structure is made up
of the following
components.
MAIN BEAMS
COLUMN
FLOOR SLABS
SECONDARY
BEAMS
Load Path in a Domestic Structure
The direction that loads are transferred through
a structure is important and must be identified.
A simple domestic structure works on similar
principles as a large concrete structure although
the components are different:

the foundation supports the footings

the footings support the flooring structure which
consist of bearers, joists and flooring

the stud walls and bracing transfer their load to the flooring

the roof trusses support the battens which support
the roof cladding and this load is transferred to the walls.
Load Path
•
A diagram shows the
framing of the roof, wall,
floor, footing and
foundation of a building.
•
The load of the path is
shown in the diagram.
ROOF
WALL
FLOOR
FOOTING
FOUNDATION
Load Path
STRUCTURAL
COMPONENT
LOAD PATH
Roof
Roof load are transfer to roof
beam
Wall
Wall load is transfer to beam
Floor
Slab
Carry direct applied load and
transfer it to
beam
Beam
Carry load from floor slab and
transfer it to column
Column
Carry load from beam and
transfer it to foundation
Foundation
Carry and distribute building
load to soil beneath
Nature of Load

Point Load
•
A point load

often abbreviated to
P
or
L

is a load acting at a single point.

sometimes called a concentrated load.
•
Example;

Roof truss supported on a top plate

As the contact area of a truss on the top plate is small,
the load is assumed to be concentrated at a point.
Nature of Load

Point Load
•
A diagram shows a plank of timber
appearing horizontally above a
roof truss.
•
At the end of the plank is an arrow
showing the information P or L
units kN.
•
On either side of the roof truss is a
top plate.
•
Where the top plate and roof truss
intersects is a an arrow indicating
P or L.
Nature of Load

Uniformly Distributed
Load
•
A uniformly distributed load (UDL)

is a load that is evenly spread along a length
or across an area.
•
For example, the loads supported by a
typical beam include:
• the beam’s own weight
• the weight of the floor slab it is supporting
• the live load supported by the floor slab.
Nature of Load

Uniformly Distributed
Load
•
These loads are consistent along the entire
length of the beam.
•
The load may be represented as ;
i) rate per linear metre (kN/m) for beams
ii) rate per square metre (kN/m
2
) for slabs.
Nature of Load

Uniformly Distributed
Load
•
A diagram shows a beam with
the load distributed all along
its length.
•
The load is labelled UDL with
units shown as kN/m or
kN/m
2
.
•
A reinforced concrete beam is
displayed and labelled with
UDL equal to 4.3 kN/m.
•
A reinforced concrete slab is
displayed and labelled 2.7
kN/m
2
.
Nature of Load

Uniformly Varying
Load
•
A uniformly varying load

is a load that is distributed along the length
of a linear element such as a beam,
but instead of the load being evenly spread it
varies in a linear fashion.
•
Example ; Retaining wall.

is designed to hold back earth, which exerts a
horizontal force on the back of the retaining wall.
Nature of Load

Uniformly Varying
Load
•
A diagram shows a vertical
section through a retaining
wall.
•
The retaining wall is in the
shape of an upside down
‘T’. The earth to the left of
the wall is labelled ‘retained
earth pushes horizontally at
back of wall’.
Nature of Load

Uniformly Varying
Load
•
A diagram shows a symbolic
representation of a uniformly
varying load on a retaining wall.
•
This shows a number of arrows
pointing to the right. The length
of these arrows indicates the
strength of the load on the wall
at different heights.
•
The load is smallest at the top of
the wall and greatest at the base
of the wall.
•
A right angled triangle is drawn
around these arrows to further
illustrate this point.
•
Moments are a
measure of the turning
effect of a force around
a specified turning point
or pivot.
•
A moment is a
force
times a
distance
. The
unit used to measure a
moment is newton
metres (Nm).
Nature of Load

Moments
M = F x d
M = 10 N x 5 m
M = 50 Nm
Note that the units are Nm (
newton
metres
)
not N/m (
newtons
per
metre
).
Nature of Load

Moments
•
The direction of a moment is
opposite
to the direction of the force
Nature of Load

Moments
•
The convention is that:
•
clockwise
moments are positive
•
anti

clockwise
moments are negative.
Nature of Load

Moments
MAIN BEAMS
ARE SUPPORTED BY COLUMN
BACK
COLUMN
ARE ARRANGED IN A GRID PATTERN
BACK
SLABS
ARE SUPPORTED BY THE MAIN BEAMS
BACK
SECONDARY BEAMS
ARE SUPPORTED BY
THE MAIN BEAMS
BACK
Roof
The roof load path flows
down through the walls to
the foundation.
BACK
Wall
The wall load path flows
down through the floor to
the foundation.
BACK
Floor
The floor load path flows
down through the footing
to the foundation.
BACK
Footing
The footing load path
flows down through to
the foundation.
BACK
Foundation
The foundation
supports the footings.
BACK
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