stresses found in structural members. forces acting simply supported beam 1.bending
TRANSCRIPT
Stresses Found In Structural Members
Forces Acting Simply Supported Beam
1.Bending
Bending
Support Wall Below
Load Load Applied
A
A
Beam will want to Bend
Bending
Support Wall Below
Load Load
A
A
We would prefer if it did this
Tension Induced
Support Wall Below
Load Load
A
A
Tension Induced
Support Wall Below
Load Load
A
A
Tension
If is does what we want
Counteract Tension
Support Wall Below
Load Load
A
A
Tension
Reinforcement to counteract
Counteract Tension
Support Wall Below
Load
Reinforcement as low as possible
Load Load
Tension
Effe
ctiv
e D
epth
Reo for crack control
Forces Acting Simply Supported Beam
Compression
Compression Induced to Top of Beam
Support Wall Below
Load Load
A
A
Tension
Compression
Usually the Concrete can Withstand without Reo
Compression Acting at Supports
Support Wall Below
Load
Reinforcement as low as possible
Load Load
Tension
Effe
ctiv
e D
epth
Reo for crack control
Compression Acting at Supports
Support Wall Below
Load
Reinforcement as low as possible
Load Load
Tension
Effe
ctiv
e D
epth
Reo for crack control
For high compression reo will prevent surcharge
Compression Acting at Supports
Support Wall Below
Load Load
A
A
Compression Acting at Supports
Wall Below
Load
Section A-A
Compression Acting at Supports
Wall Below
Load
Compression Acting at Supports
Wall Below
Load
Beam compressed against support by load
Compression Acting at Supports
Wall Below
Load
Stirrups placed to prevent bursting
Compression Acting at Supports
Support Wall Below
Load
Stirrups closely spaced to prevent bursting
Load Load
Compression Acting at Supports
Support Wall Below
Load
Stirrups spaced further apart as no compressive force
Load Load
Compression Acting at Supports
Support Wall Below
Load
Stirrups required to support top steel – FRAMING BARS
Load Load
Forces Acting Simply Supported Beam
Shear
Shear Acting On Simply Supported Beam
Support Wall Below
Load Load
A
A
What is Shear?
Shear
2 Types of Shear Forces
• Vertical Shear
• Horizontal Shear
Shear Forces
• Vertical Shear
Shear Forces
Support Walls Below resist downward force
Load Load Load
Shear Forces
No Resistance where there is no support
Load Load Load
Shear Forces
Beam will shear at support
Load Load Load
Shear Forces
Reinforcement at supports to resist shear
Stirrups omitted for clarity
Load Load Load
A
A
B
B
Shear Forces
Support Walls Below resist downward force
Load Load Load
Shear Forces
• Horizontal Shear & Diagonal Shear
Horizontal Shear
Support Wall Below
Load
Reinforcement to Prevent Horizontal Shear if requiered
Load Load
When 2 Types of Shear Forces Meet• Diagonal Tension Cracking
Diagonal Shear
Support Wall Below
Load
Stirrups Prevent Diagonal Shear
Load Load
Multi Span Beam
Load on Continuous span Bean
Support Walls Below
Load Load
Load on Continuous span Bean
Support Walls Below
Load Load
Load on Continuous span BeanLoad Load
Tension Tension
Tension
Forces that act on Beams
Compression
Shear
Bending
BendingCompression
ShearShear
Bending
Shear
Compression
Load Load
Contra flexure
Point of Maximum Bending
Point of Maximum Bending
Point of Maximum Bending
Contra flexure
Bending Reduces
Bending Reduces
Bending Reduces
Contra flexure
ZERO Bending
ZERO Bending
ZERO Bending
Fixed End Beam
Load on Continuous span Bean
Support Walls Below
Load Load
Fix
ed C
onne
ctio
n
Load on Continuous span Bean
Support Walls Below
LoadLoad
Fix
ed C
onne
ctio
n
Tension Tension
Tension Tension
Compression Acting at Supports
Support Walls Below
Load Load
Compression Acting at Supports
Support Walls Below
Load Load
Fixed End Beams
Support Walls Below
Load
Point of Contra flexure
Load Load
Forces that act on Beams
Fixed or Restrained End
Compression
Shear
Bending
Bending Compression
ShearShear
Bending
Bending
Shear
Compression
Load Load
Cantilevers
Compression Acting at Supports
Support Walls Below
Load Load Load
Compression Acting at Supports
Support Walls Below
Load Load Load
Point of Contra flexure
Forces That Affect Columns
Forces That Affect ColumnsLOAD
Forces That Affect ColumnsLOAD
Bursting Force`
Bursting Force`
Bursting Force`
Bursting Force
Bursting Force
Bursting Force
Compression Acting at Supports
Column compressed by load
Compression Acting at Supports
Stirrups to Counteract
S4[1].03Purnell Bros
Stirrups to prevent Bursting
Forces That Affect Columns
Bending
S4[1].03Purnell Bros
It is difficult to predict which way columns will bend
S4[1].03Purnell Bros
Columns must also be able to withstand mechanical impact
Resist bending
S2 Naremburn Church
Forces That Affect WallsNo Top Restraint
Shear
Forces That Affect Retaining Walls
Forces That Affect Retaining Walls
Footing
Retained Load
Forces That Affect Retaining Walls
Footing
Retained Load
Forces That Affect Retaining Walls
Retained LoadReinforcement in this location is virtually useless
Forces That Affect Retaining Walls
Retained Load
Reinforcement as close as possible to load
Forces That Affect Retaining Walls
Retained Load
Reinforcement as close as possible to load
Reinforcement should be embedded to maximum depth
Forces That Affect Retaining Walls
Retained Load
Reinforcement as close as possible to load
Reinforcement should be embedded to maximum depth
Forces That Affect Retaining Walls
Retained Load
Shear
Forces That Affect Retaining Walls
Retained Load
ShearShear force overcome by Reinforcement at Base
Forces That Affect Retaining Walls
Retained Load Wall will act as a Cantilevered Beam
Ten
sio
n
S1 – 21 St Lukes Grammer
St Lukes Grammer S1 -23
S012 Cardiff Markets
Forces That Affect Retaining Walls
Footing
Retained Load
Forces That Affect Retaining Walls
Footing
Retained Load
Forces That Affect Retaining Walls
Retained LoadReinforcement is virtually useless
Ten
sio
n
Forces That Affect Retaining Walls
Retained Load
Reinforcement as close as possible to load
Ten
sio
n
Forces That Affect Retaining Walls
Retained Load
Reinforcement as close as possible to load
Reinforcement should be embedded to maximum depth
Ten
sio
n
Forces That Affect Retaining Walls
Retained Load
Reinforcement as close as possible to load
Reinforcement should be embedded to maximum depth
Ten
sio
n
Forces That Affect Retaining Walls
Retained Load
Shear
Forces That Affect Retaining Walls
Retained Load
Shear
Shear force overcome by Reinforcement at Base
Forces That Affect Retaining Walls
Wall will act as a Cantilevered Beam
Ten
sio
n
S1-21
Forces That Affect Retaining WallsWith Top Restraint
Footing
Retained Load
First Floor Slab
Forces That Affect Retaining Walls
Footing
Retained Load
First Floor Slab
Shear
Shear
Forces That Affect Retaining Walls
Footing
Retained Load
First Floor Slab
Shear
Shear
Forces That Affect Retaining Walls
Retained Load
Shear
Shear
Forces That Affect Retaining Walls
Retained Load
Forces That Affect Retaining Walls
Retained Load
Ten
sio
n
Ten
sio
nTe
nsi
on
Forces That Affect Retaining Walls
Retained LoadWall will act as beam restrained at ends
Ten
sio
n
Ten
sio
nTe
nsi
on
Forces That Affect Retaining Walls
Retained LoadReinforcement at Centre as far from load as practical – Maximum Bending
Ten
sio
n
Ten
sio
nTe
nsi
on
Forces That Affect Retaining Walls
Retained LoadWall will have a point of Contra flexure
Ten
sio
n
Ten
sio
nTe
nsi
on
Section 11 @ S1-02
Walls not Retaining Loads
Stability
Force
Force may be;• Wind• Earthquake• Impact
Stability
Force
Force may be;• Wind• Earthquake• Impact
Stability
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Stability
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Embedment is Critical
Stability
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective Width Embedment is Critical
StabilityTypical Configuration
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective Width
Shear Reinforcement
Tension Reinforcement
Embedment is Critical
StabilityTypical Configuration
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective Width
Shear Reinforcement
Tension Reinforcement
Embedment is Critical
Stability
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective Width
Force
Embedment is Critical
Stability
Force
Effective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective Width
Force
StabilityEffective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective WidthEmbedment is Critical
Embedment is Critical
StabilityEffective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective WidthEmbedment is Critical
Embedment is Critical
Shear Reinforcement
Tension Reinforcement no need to embedIn base or top
StabilityEffective Width
Force may be;• Wind• Earthquake• Impact
Direction of force may not be predictable
Effective WidthEmbedment is Critical
Embedment is Critical
Shear Reinforcement
Tension Reinforcement no need to embedIn base or top