Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Reaction on a support connection For rolled section For pin section
For fixed section FyFy FyFy FxFx FyFy FxFx M
Slide 3
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
To design a structure it is necessary to know in each member: 1.
Bending moments 2. Torsion moments 3. Shear forces 4. Axial
forces
Slide 4
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Equilibrium The goal of the whole design process is to achieve an
equilibrium of the forces acting upon a structure. Without
equilibrium the building will move and that is not good!
Equilibrium must be accomplished for the building as a whole and
for all the parts or smaller assemblies within the building as
well. For all of the forces acting downward due to gravity, an
equal, opposite force called a reaction must be pushing up. All of
the loads acting on a structure will ultimately accumulate in the
foundation and must be met with an equivalent reaction from the
earth below.
Slide 5
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Force Forces are a type of quantity called vectors Defined by
magnitude and direction Statement of equilibrium Net force at a
point in a structure = zero (summation of forces = zero) Net force
at a point is determined using a force polygon to account for
magnitude and direction
Slide 6
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Forces in Structural Elements 100 lb Compression 100 lb
Tension
Slide 7
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Forces in Structural Elements 100 lb Bending Torsion
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Shear Force & Bending Moment Two parameters which are
fundamentally important to the design of beams are shear force and
bending moment. These quantities are the result of internal forces
acting on the material of a beam in response to an externally
applied load system.
Slide 12
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Static Equilibrium Since the externally applied force system is in
equilibrium, the three equations of static equilibrium must be
satisfied, i.e. +ve Fy = 0 The sum of the vertical forces must
equal zero. +ve M = 0 The sum of the moments of all forces about
any point on the plane of the forces must equal zero. +ve Fx = 0
The sum of the horizontal forces must equal zero. * The assumed
positive direction is as indicated.
Slide 13
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Equations of Equilibrium A structure or one of its members in
equilibrium is called statics member when its balance of force and
moment. In general this requires that force and moment in three
independent axes, namely
Slide 14
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Equations of Equilibrium In a single plane, we consider
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Shear Force Diagram (SFD) The calculation carried out to determine
the shear force can be repeated at various locations along a beam
and the values obtained plotted as a graph; this graph is known as
the shear force diagram. The shear force diagram indicates the
variation of the shear force along a structural member.
Slide 18
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Bending Moment Diagram Bending inducing tension on the underside of
a beam is considered positive. Bending inducing tension on the top
of a beam is considered negative.
Slide 19
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Bending Moment Diagram Note: Clockwise/anti-clockwise moments do
not define +ve or ve bending moments. The sign of the bending
moment is governed by the location of the tension surface at the
point being considered. As with shear forces the calculation for
bending moments can be carried out at various locations along a
beam and the values plotted on a graph; this graph is known as the
bending moment diagram. The bending moment diagram indicates the
variation in the bending moment along a structural member.
Slide 20
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Shear Force and Bending Moment Diagram If the variations of V &
M are plotted, the graphs are termed the shear diagram and moment
diagram Changes in shear= Area under distributed load diagram
Changes in moment = Area under shear diagram
Slide 21
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Shear and Moment Diagram
Slide 22
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Shear and Moment Diagram
Slide 23
Controlled Environment Design 1 Siti Kamariah Md Saat, Unimap
Relationship of Loading, Shear and Moment
