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Water tank load on slab
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ramu_se
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PostPosted: Mon May 23, 2022 3:27 pm    Post subject: Water tank load on slab Reply with quote

Hi All,

How to distribute the water tank load (syntax tank) of 1000 lit capacity on a slab?

For example,

Consider the slab area of 3.0m x 2.0m = 6 m2

water tank load = 1000 lit = 10kN

Load/m2 = 10/6 = 1.6 kN/m2

Is it the Correct method? or

Do we need to distribute the load according to the diameter of the tank?

How to distribute the load if we place a tank in the corner of the slab?

How much extra reinforcement needs to be provided in the corner of the slab?

Kindly guide me.

Thank you,
Ramu.



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vikram.jeet
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PostPosted: Tue May 24, 2022 4:33 am    Post subject: Reply with quote

Water tank

It is always preferable to place  syntax tank on staging so that cleaning is possible beneath tank apart from relieving roof slab of additional loading.
Staging : I steel girder with angle irons /T sections supporting stone slabs  platform with topping 50 to 75mm and reinforced with 8 dia@ 200 bothways can act as platform .I girder shall rest on load veg walls/ rcc beams.

In case you are hell bent to put tank directly on slab : additional loading if slab area is small
Weight of water divided by tank area is the load /m2 incident on top of slab . You can further dilute this load by a factor D^2/(D+2*T + 2*R)^2 where D - dia of tank
T is thickness of base slab
R thickness of roof finish , if tank is placed on roof finish otherwise nil.

In case slab area is higher it can be designed as per concentration loading given in IS 456 / IRC 21


Last edited by vikram.jeet on Tue May 24, 2022 4:37 am; edited 1 time in total
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vikram.jeet
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PostPosted: Tue May 24, 2022 4:34 am    Post subject: Reply with quote

Placing at corner is always first option.
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mjnasar
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PostPosted: Tue May 24, 2022 4:51 am    Post subject: Re: Water tank load on slab Reply with quote

Dear Engineer
Greetings

more conservatively

equate moments from concentrated load to uniform loads

W L / 4  = w * L 2 / 8

10 * 2 / 4 = w * 2 * 2 / 8

x = 10kn/m2

( provide required reinforcement for 10kn/m2+finishing + Self weight as  two way slab)


Best regards



ramu_se wrote:
Hi All,

How to distribute the water tank load (syntax tank) of 1000 lit capacity on a slab?

For example,

Consider the slab area of 3.0m x 2.0m = 6 m2

water tank load = 1000 lit = 10kN

Load/m2 = 10/6 = 1.6 kN/m2

Is it the Correct method? or

Do we need to distribute the load according to the diameter of the tank?

How to distribute the load if we place a tank in the corner of the slab?

How much extra reinforcement needs to be provided in the corner of the slab?

Kindly guide me.

Thank you,
Ramu.
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tosifsayyed
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PostPosted: Wed May 25, 2022 6:51 am    Post subject: Reply with quote

Water tank load is calulated by unit wt of water x height/depth of water. For 1000 lit sintex tank, generally the height is 1.2-1.3m (kindly confirm with product catlouge), So water load will be = 1.2*10 = 12kN/m2.

Most of the time it is difficult to predict exact location of water tank, because of other stackholders. For smaller slabs (2x2,2x3,4x2), so on a conservative side entire slab can be designed with this water load adding up with other loads, as diameter of tank is almost equal to shorter span.

For bigger slab area (4x6, 6x6 etc) any of the method stated by Honourable Vikramjeet sir and MJ Nasar sir can be followed, just one care should be taken to define exact location of water tank on drawing and supervising it properly.


Regards-

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vikram.jeet
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PostPosted: Wed May 25, 2022 10:44 am    Post subject: Reply with quote

A very sane view from Er Tosif Sayyed
Water tank plaCement location is always decided later post  construction especially in case of  syntax type tanks. It can be placed by owner any where and tanks are further added.  So considering ht of water load as intensity is better in small sized panels.

tosifsayyed wrote:
Water tank load is calulated by unit wt of water x height/depth of water. For 1000 lit sintex tank, generally the height is 1.2-1.3m (kindly confirm with product catlouge), So water load will be = 1.2*10 = 12kN/m2.

Most of the time it is difficult to predict exact location of water tank, because of other stackholders. For smaller slabs (2x2,2x3,4x2), so on a conservative side entire slab can be designed with this water load adding up with other loads, as diameter of tank is almost equal to shorter span.

For bigger slab area (4x6, 6x6 etc) any of the method stated by Honourable Vikramjeet sir and MJ Nasar sir can be followed, just one care should be taken to define exact location of water tank on drawing and supervising it properly.


Regards-
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vikram.jeet
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PostPosted: Thu May 26, 2022 8:04 am    Post subject: Reply with quote

Syntax WT staging at corner :

It requires only one steel girder placed diagonally to accomodate the tank dia. Angle irons/T irons can be placed with stone slabs. The girder support is ready available fm orthogonal walls  of staging ht .
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ramu_se
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PostPosted: Fri May 27, 2022 12:14 pm    Post subject: Reply with quote

Thank you Sir.
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ramu_se
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PostPosted: Sat May 28, 2022 11:27 am    Post subject: Reply with quote

Sir,

Can you share any pictures of the staging for the water tank and the size of the girder?

Thanks,
Ramu.
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vikram.jeet
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PostPosted: Sun May 29, 2022 4:10 am    Post subject: Reply with quote

Er Ramu

There is no standard size of girder. It needs to be designed as simply supported steel beam  based on staging and tank load shared by steel beam.

Just simple illustration  :  For 2500 liters capacity syntax tank ( size not actual , pl see catalogs , assumed just for illustrating)

Dia of syntax tank = 1.5 m  ,  Ht = 1.5m  ( at overflow )

In case tank staging placed along short direction wall of length =3,0m
Width of staging (perpendicular to wall ) = 2.0m say
Also needed two brick pillars of size say 460x460 on each side  placed directly above room walls on two sides

Staging weight :
Stone slab  0.040x2700 = 108 kg/m2
Ceiling finish if any = 20 kg/m2
Light rcc Topping 0.075x2400 = 180 kg/m2
Total Staging wt = 108 + 20 + 180 =308 kg/m2

Wt of water tank = (3.142 1.5^)/4  x 1.5 x 1000= 2650 kg ( water tank load under overflow condition )
Self wt of syntax tank = 15 kg say

Total WT wt = 2650 +15 =2665 kg

Span of girder = 3.0 + 0.23 = 3.23m  I.e c/c pillars
Assuming self wt of steel girder = 20 kg/m

BM of girder at midspan assuming placement at center a ND taking tank load as nearly pt load
BM = (308x2.0/2+ 20) x 3.23^2/8  plus ( 0.52665x 3.23/4) =

=428 + 1076= 1504  kgm

Steel beam Z required = 1504x100 /1650 = 91 cm3

(Bending stress in tension is 1650 kg/cm2 but since girder on compression side I.e. at top has Stone slab angle iron s as lateral restraint along with Topping,  same stress for bending comp taken.

Provide ISMB 150 @14.9 kg/m steel beam
Deflectioncheck can be performed  , can be relaxed

(To be contd)


Last edited by vikram.jeet on Sun May 29, 2022 6:40 am; edited 2 times in total
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