Civil Engineering Reference
In-Depth Information
C
A
B
a
L
(
L
-
a
)/
L
Shear at location C
a
/
L
1
Shear at location A
FIGURE 5.5
Influence lines for shear at locations C and A for concentrated moving loads
applied directly to the superstructure.
influence lines may be simplified by determining the value of the effect at locations
where changes in the influence line will occur (i.e., supports, panel points, hinges,
etc.) and joining those locations with straight lines.
∗
5.2.1.2.1 Influence Lines for Maximum Shear Force and Bending
Moment in Simply Supported Beam and Girder Spans
5.2.1.2.1.1 Maximum Shear Force (with Loads Applied Directly to the
Superstructure)
The influence lines for shear force at location C and at the end of
the simple span (locationA) are shown in
Figure 5.5.
They are developed by determin-
ing the shear force at location C and reaction at the end of the simple span (location
A) with a unit load placed at locations A, B, and C.
5.2.1.2.1.2 Maximum Shear Force (with Loads Applied to the Superstruc-
ture through Transverse Members)
The influence line for shear in panel BC of
the simply supported span is shown in
Figure 5.6.
It is developed by determining the
shear force at locations B and C with a unit load placed at locations A, B, C, and D;
where,
n
is the number of panels,
n
L
is the number of panels left of panel BC, and
n
R
∗
For axial force, shear force and bending moment in statically determinate structures, influence lines
comprise straight-line segments. However, for deflections this is not the case.
