Civil Engineering Reference
In-Depth Information
Figure 5.11
Mean and effective background
load distributions for a 160 m tower (Holmes,
1996b).
Figures 5.10 and 5.11 give examples of background loading distributions calculated using
these methods. Figure 5.10 shows examples of peak load (mean+background)
distributions for a support reaction (dashed) and a bending moment (dotted) in an arch
roof. These distributions fall within an envelope formed by the maximum and minimum
pressure distributions along the arch. It should also be noted that the distribution for the
bending moment at
C
includes a region of positive pressure.
Figure 5.11 shows the background pressure distribution for the base shear force and
base bending moment on a lattice tower 160 m high, determined by calculation using
Equation (5.35) (Holmes, 1996b). The maxima for these distributions occur at around 70
m height for the base shear and about 120 m for the base bending moment. An
approximation (Holmes, 1996b) to these distributions, which is independent of the load
effect but dependent on the height at which the load effect is evaluated, is also shown in
Figure 5.11.
5.4.4
Load distributions for resonant response (single resonant mode)
The equivalent load distribution for the resonant response in the first mode can be
represented as a distribution of inertial forces over the length of the structure. Thus, an
equivalent load distribution for the resonant response,
f
R
(z),
is given by:
(5.39)
