e-mosty March 2019 Long Span and Multiple Span Bridges | Page 36
Specific Details
Overall length of all bridges
Maximum height of the main pylons
Deck width of the Suspension Bridge
Deck thickness of the Suspension Bridge
Pile diameter of the foundation of the Suspension Bridge
Pile number of each pylon of the foundations
Pile lengths of the foundations of the Suspension Bridge
Anchorage, South: diameter
depth of the anchorage
Anchorage, North: diameter
depth of the anchorage
L = 3,003m
H = 143.14m
B = 25.60m
d = 3.00m
Φ = 2.20m
24 pieces
max. L = 110.00m
d = 50.00m
h = 36.00m
d = 50.00m
h = 11.35m
THE DECK
The proportions of the deck of the Suspension
Bridge are shown in the following “Drawings
Section” illustrating the symmetrical geometry. Another major challenge was to design the bridge
for wind loads which can achieve values up to
250km/h = 69.44m/s.
The deck has a slender depth and contrasts well
with the stockier towers. In the past many cyclones have hit the coast of
Maputo Bay and other areas of Mozambique.
Despite the aesthetic slenderness, this deck is
designed to resist fluttering phenomenon caused
by wind in an area where cyclone occurs. For this reason, data was collected and scrutinized
very carefully with all the measured wind speeds
since 1973.
PYLONS The data were provided by “Instituto Nacional de
Metereologia de Mocambique”.
The main Pylons are concrete and each consists of
two hollow legs 7m x 5m in section, with horizontal
bracing beams at 1/3 and 2/3 height and near the
top.
WIND AND EARTHQUAKE LOADS FOR THE DESIGN
OF THE SUSPENSION BRIDGE
The Bridge in Maputo is positioned at the end of
an axis which is starting in Djibouti and ending in
Mozambique, on the east of an active tectonic
plate.
The axis is follows the path Djibouti-Ethiopia-
Uganda-Rwanda-Burundi-Borderline Tanzania /
Congo-Malawi-Mozambique.
Along this axis the tectonic plates move and the
consequence is the risk of severe earthquakes.
By statistical analysis of all these collected wind
speeds, using the Gumbel Method the derived
value of the basic wind speed was:
v = 35.77m/s,
for 100yr return period, at a height of 10m above
sea level (as recommended in the wind tunnel test
Report as well).
The loading experienced by the deck was
estimated in the wind tunnel report.
As the height of the Suspension Bridge above the
sea level is approximately 64m, the design wind
speed was evaluated to:
v = 49 m/s.
The wind tunnel test for the chosen deck of the
Suspension Bridge resulted in a flutter wind speed:
1/2019
v = 73 m/s.