Date post: | 02-Mar-2018 |
Category: |
Documents |
Upload: | antony-prasanth |
View: | 226 times |
Download: | 0 times |
of 12
7/26/2019 18447_lec 6.ppt
1/12
Forces Acting on DamsForces Acting on Dams
To design a dam, various forces must beTo design a dam, various forces must beconsidered to insure the safety of theconsidered to insure the safety of the
dam. The most important forces aredam. The most important forces are::
1.1. Weight of damWeight of dam2.2. Water PressureWater Pressure
3.3. p!iftp!ift".". Wave pressureWave pressure#.#. $arth%ua&e forces$arth%ua&e forces
7/26/2019 18447_lec 6.ppt
2/12
' Weight of DamWeight of Dam
The (eight of the dam is ca!cu!ated asThe (eight of the dam is ca!cu!ated as
fo!!o(s)fo!!o(s)
WhereWhere **mmis the speci+c (eight of theis the speci+c (eight of the
dams materia!.dams materia!.
xVolumeWm
=
7/26/2019 18447_lec 6.ppt
3/12
' Water PressureWater Pressure
Water pressure acts perpendicu!ar to theWater pressure acts perpendicu!ar to the
surface of the dam and is ca!cu!ated persurface of the dam and is ca!cu!ated per
unit (idth as fo!!o(s)unit (idth as fo!!o(s)
WhereWhere **( is the speci+c (eight of (ater and( is the speci+c (eight of (ater and
h is the height of (ater.h is the height of (ater.
2
2
1 hPw
= Pw
h/3
h
7/26/2019 18447_lec 6.ppt
4/12
' p!iftp!ift
Dams are sub-ected to up!ift forceDams are sub-ected to up!ift forceunder its base. p!ift acts up(ard.under its base. p!ift acts up(ard.
Where is the (idth of the base of theWhere is the (idth of the base of thedam.dam.
hBU w21=
h
U
B
B/3
7/26/2019 18447_lec 6.ppt
5/12
' Wave PressureWave Pressure
The upper part of the dam /above theThe upper part of the dam /above the
(ater !eve!0 is sub-ected to the(ater !eve!0 is sub-ected to the
impact of (aves. The maimumimpact of (aves. The maimum
(ave pressure per unit (idth is)(ave pressure per unit (idth is)
Where hWhere h((is the (ave height.is the (ave height.
vwv hP 4.2=
Pw
0.375hw h
w
7/26/2019 18447_lec 6.ppt
6/12
$arth%ua&e Forces$arth%ua&e Forces
Dams are sub-ected to vibration duringDams are sub-ected to vibration during
earth%ua&es. ibration aects both theearth%ua&es. ibration aects both the
body of the dam and the (ater in thebody of the dam and the (ater in thereservoir behind the dam. ibrationreservoir behind the dam. ibration
forces are function of both the intensityforces are function of both the intensity
/4echter 5ca!e0 and its duration. The/4echter 5ca!e0 and its duration. The
most danger eect occurs (hen themost danger eect occurs (hen thevibration is perpendicu!ar to the face ofvibration is perpendicu!ar to the face of
the dam.the dam.
7/26/2019 18447_lec 6.ppt
7/12
' ody Forces)ody Forces)
ody force acts hori6onta!!y at theody force acts hori6onta!!y at thecenter of gravity and is ca!cu!ated as)center of gravity and is ca!cu!ated as)
WhereWhere 77is the earth%ua&e coe8cientis the earth%ua&e coe8cientand W is the (eight of the dam. 9sand W is the (eight of the dam. 9sta&en :.2 for practica! reasons.ta&en :.2 for practica! reasons.
WPem =
W1
0.1 W1
W2
0.1 W2
7/26/2019 18447_lec 6.ppt
8/12
' Water Force)Water Force)Water vibration produces a force onWater vibration produces a force on
the dam acting hori6onta!!y;the dam acting hori6onta!!y;
Where
7/26/2019 18447_lec 6.ppt
9/12
' $amp!e)$amp!e)
2.# t?m33,, **((>1 t?m>1 t?m33, h( > 1.# m, h( > 1.# m
6m
24m
30m
10m
33m
7/26/2019 18447_lec 6.ppt
10/12
' 1. Weight of (ater1. Weight of (ater
WW11>2.# @ @ ": > :: t>2.# @ @ ": > :: t
WW22>2.# @:.#@1=@3:>2.# @:.#@1=@3:
> B# t> B# t
' 2. Water Pressure2. Water Pressure
P > :.# @ 1.: @ /330P > :.# @ 1.: @ /33022
> #"".# t> #"".# t
(1 (2
P
7/26/2019 18447_lec 6.ppt
11/12
' 3. p!ift3. p!ift
> :.# @ 1.: @ 33 @ 2" > :.# @ 1.: @ 33 @ 2" > 3C t> 3C t
' ". Wave Pressure". Wave PressurePP((> 2." @ 1.: @ 1.#> 2." @ 1.: @ 1.#
> 3. t> 3. t
P(
7/26/2019 18447_lec 6.ppt
12/12
' #. $arth%ua&e Forces#. $arth%ua&e Forces
a. ody Forcesa. ody Forces
PPem1em1> :.1 @ ::> :.1 @ ::
> : t> : t
PPem2em2> :.1 @ B#> :.1 @ B#> B.# t> B.# t
b. (ater Forceb. (ater Force
PPe(e(>/2?30@:.=2@:.1@/3302>/2?30@:.=2@:.1@/3302
> #C.## t> #C.## t
Pem1
Pem2
Pe(