of forces to be considered while designing a well foundation are as follows:**1.
Dead loads: it includes weight of superstructure (pier/abutment) + self weight
3. Live loads: the design live loads incase of railway bridges are extracted
from I dial Railway bridge rule and codes. For road bridges, the live loads may
be specified via standard specifications and code of practice for road bridges.
5. Impact loads: the impact loads is the result of live load and shall be
considered only during the design of a pier cap and the bridge seat on the
abutment. However, for other components of the well this effect shall be
7. Wind loads: the wind loads shall be seen only on the exposed area in
elevation and hence acts laterally on the bridge.
9. Water pressure: the water pressure due to water current is acted on the
portions of substructure that lies between the water level and the maximum scour
level. In case of piers lying parallel to the direction of water, the intensity
of water shall be determined by, **P = kV2 **Where, p = intensity of pressure
(KN/m2), k = constant that depend upon the shape of well. Maximu 8m — 0.788 for
square ended piers, Minimum — 0.237 for piers having cut and ease/clam water, V-
–Velocity of current/water flow (m/s), An assumption is made that V2 is maximum
at free surface of water and zero at the deepest scour level. The velocity at
surface is assumed to be ?2 times the average velocity.
11. Longitudinal forces: longitudinal forces results from tractive and braking
forces. The longitudinal forces depend on the type of vehicles and bearing.
These forces get transferred/transmitted into the substructure via fixed
bearings and friction in movable bearings.
13. Centrifugal force
15. Buoyant forces: the buoyancy tends to decrease the effective weight of
well. For masonry/concrete steining 15-20% buoyancy is assumed to account for
17. Earth pressure: The Rainkines�s theory and Coulombs theory is utilized to
calculate the earth pressure.
19. Temperature stresses: the longitudinal forces are resulted because of the
temperature changes. The movements caused by temperature changes are partly
restrained in the girder bridges due to friction at the moveable end.
21. Seismic forces: seismic forces are vital when the wells are constructed in
seismic zones. The seismic forces act on every members of the superstructure.
These forces is principally determined as, ?W, where w= weight of component and
?=seismic coefficient which depends upon the type of seismic zone and its value
shall extracted from code. Usually taken between 0.01-0.08. This seismic force
is characterized to cat through the C.G. of the component. These may act in any
direction but generally assumed to act in one direction at a time.
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