Structural Design of Swimming Pools

DEVELOPMENT OF BEACH HOTEL & RESORT, PLOT NO. (SB-06) SAADIYAT ISLAND, ABU DHABI, UNITED ARAB EMIRATES Structural Design of Swimming Pools

DEVELOPMENT OF BEACH HOTEL & RESORT, PLOT NO. (SB-06) SAADIYAT ISLAND, ABU DHABI, UNITED ARAB EMIRATES STRUCTURAL DESIGN OF SWIMMING POOLS

Section

Page

1.

Introduction

2

2.

Geotechnical Design Data

3

2.1

Site Condition and Recommendation

3

3.

Design Criteria

3

3.1

Design Loading

3

3.2

Load Combinations

4

3.3

Materials

4

3.4

Concrete Cover

5

3.5

Crack Control

5

3.6

Codes and Standards

5

4.

Design of Vertical Wall & Base Slab

6

5.

Check of Early Thermal Cracking

11

6.

Check Soil Bearing Capacity

12

09 Aug. 2010

Page 1 of 12


1.

Introduction This design calculation shall cover the structural design of the swimming pools structures for BEACH HOTEL & RESORT, PLOT (SB-06), SAADIYAT ISLAND. This design calculation shall cover the following swimming pools: No.

09 Aug. 2010

Structure Name

Approximate Length

Approximate Width

Water Depth

1

Garden Villa Swimming Pool

4.25

3.60

1.10

2

Royal Garden Villa Swimming Pool Type 1

9.00

3.00

1.10

3

Royal Garden Villa Swimming Pool Type 2

4.20

3.00

1.10

4

Swimming Pool Type 1

30.00

15.60

0.90 / 1.40

5


21.50

11.00

1.00

6


Length & Width are Varied

0.90

7

Cabana Plunge Pool


0.90

8

Kid's Pool


0.45

9

Ryad Single Story Villa Swimming Pool

4.00

3.00

1.10

10

Ryad Double Story Villa Swimming Pool

4.60

2.00

1.10

Page 2 of 12


2.

Geotechnical Design Data

2.1

Site Condition and Recommendation Since there is no available information about the site condition, the soil bearing capacity 2 shall be assumed 50kN/m . The foundation designs will be verified against the data and recommendations received from the soil investigations.

3.

Design Criteria

3.1

Design Loading

3.1.1

Dead Load The following densities and dead load allowances will be adopted in the design of the structural elements:

3.1.2

Density of Reinforced Concrete

25.0 kN/m

3

Density of Unreinforced Concrete

23.0 kN/m

3

Density of Soil

20.0 kN/m

3

Submerged Density of Concrete

10 KN/m

3

Submerged Density of Soil

10 KN/m

3

Super Imposed Load The following super imposed dead loads shall be taken into account:

3.1.3

•

Floor Finishes

1.5 KN/m

2

•

Services

1.0 KN/m

2

Live Load The following live loads shall be taken into account:

3.1.4

7.50 KN/m

2

•

Loading Bay

•

Sand load shall be additive to live loads when area under consideration is used as 2 a work area. A 0.75 kN/m load shall be used in design of slabs.

Earth Pressure For the design of earth retaining structural elements, the earth pressure will be determined as follows: Ka (active earth pressure) = 1–sin ¢ / 1+sin ¢ = 0.33

(used for check of stability)

Kp (passive earth pressure) = 1+sin ¢ / 1-sin ¢ = 3.0 Ko (at rest pressure) = 1-sin ¢ = 0.50

(used for design of section) º

Where ¢ is angle of internal friction, and it is equal to 30 .

09 Aug. 2010

Page 3 of 12


3.2

Load Combinations

3.2.1

Ultimate Limit State Ultimate Limit State Combinations ULS_01

3.2.2

1.4

DL

+

1.6

LL

+

1.2

EP

+

1.4

WP

+

1.2

T

1.0

LL

+

1.0

EP

+

1.0

WP

+

1.0

T

Serviceability Limit State SLS_01

1.0

DL

+

Legend:

3.3

DL

Dead Load

LL

Live/Imposed

EP

Earth Pressure

WP

Water Pressure

T

Uniform Temperature

Materials All materials shall conform to the applicable standards as stated herein or as specif ied in the performance specification.

3.3.1

Concrete The following concrete grades and properties shall be used: Concrete Grade

Structural Element

Characteristic

Modulus of Elasticity

Strength fcu

3.3.2

C40/20

All Structural Elements

40 N/mm

2

28 KN/mm

2

C20/20

Blinding / Mass Concrete

20 N/mm

2

20 KN/mm

2

Reinforcing Steel Hot rolled reinforcement to BS 4449: 1997 will be specified with the following properties: Type

09 Aug. 2010

Designation

Yield Strength

Modulus of Elasticity

Mild Steel

R

250 N/mm

2

200 KN/mm

2

High Yield Deformed Type 2

T

460 N/mm

2

200 KN/mm

2

Page 4 of 12


3.4

Concrete Cover Element Raft

Retaining Walls

Water Tank Walls

3.5

Exposure

Min. Cover

Earth Faces

75mm

Other Faces

50mm

Earth Faces

60mm

Exposed to Weather

40mm

Water Faces

50mm

Other Faces

40mm

Crack Control For retaining aqueous liquids structures a maximum crack width of 0.20 mm shall be adopted; crack width shall be calculated to BS8007.

3.6

Codes and Standards BS 8007

Design of Concrete Structures for Retaining Aqueous Liquids

BS 8110

Structural Use of Concrete

BD 28

Early Thermal Cracking in Concrete

09 Aug. 2010

Page 5 of 12


4.

Design of Vertical Wall & Base Slab The maximum water depth

= 1.40 m.

The water pressure

= 10 * 1.40

Service Moment due to water pressure

= 0.50 * 14 * 1.40 * 1.40 / 3

= 14.0 kN/m’

= 4.57 kN.m Ultimate Moment due to water pressure

= 1.40 * 4.57 = 6.43 kN.m

The maximum wall height

= 1.60 m.

The at rest earth pressure due to soil

= 0.50 * 20 * 1.60

= 16.0 kN/m’

The at rest earth pressure due to surcharge

= 0.50 * 7.50

= 3.75 kN/m’

Service Moment due to earth pressure

= 0.50 * 16.0 * 1.60 * 1.60 / 3 + 3.75 * 1.60 * 1.60 / 2

Service Moment due to earth pressure

= 6.90 + 4.80 = 11.70 kN.m

Ultimate Moment due to earth pressure

= 1.20 * 11.70 = 14.00 kN.m

Ground water table is lower the base slab so NO bending moment on the base slab due to the water weight.

09 Aug. 2010

Page 6 of 12


Flexural Capacity of Reinforced Concrete Rectangular Section According to BS8110 Structural Design of Swimming Pools Part Title :- Design of Vertical Wall 1. Factored Bending Moments ( Kn,m ) 14

M ULT

Notations :

Kn.m

M ULT = Factored Bending Moment.

2. Properties of Concrete section & Steel

f cu cu

40

N/mm2

f cu cu = Compressive strength of concrete (Cube).

fy

420

N/mm2

f y = Yield strength of non-prestressing steel.

b

1000

mm

b = Width of rectangular section.

h

360

mm

h = Overall depth of section.

d

290

mm

d = The effective depth to the tension reinforcement.

1142

mm2

As = Total area of non-prestressing steel.

As (T16-175)

3. Steps of Design

09 Aug. 2010

z

276

mm

z = The lever arm <= 0.95d.

Mu1

115

Kn.m

Mu1 = The ultimate resistance moment - eq. (1).

Mu2

505

Kn.m


Mu capacity

115

Kn.m

Mu = The ultimate resistance moment.

As min.

540

mm2

Mu capacity

>

Mult

As provided is OK

As provided

>

As min.

As provided is OK

Page 7 of 12


Calculation of Crack Width According to BS 8110 ( Considering Stiffening Effect of The Concrete in Tension Zone ) Structural Design of Swimming Pools Part Title :- Design of Vertical Wall 1. Service Bending Moment ( Kn.m )

Notations :

M DL

6.90

Kn.m

M DL = Service bending moment due to dead load.

M LL

4.80

Kn.m

M LL = Service bending moment due to live load.

40

N/mm2

Fcu = Characteristic concrete cube strength.

210000

N/mm2

Es = Modulus of elasticity of steel.

2. Properties of Materials Fcu Es

0.20

mm

b

1000

mm

b = Width of section.

h

360

mm


d

290

mm

d = Effective depth to tension reinforcement.

mm2

As = Area of tension reinforcement.

Allowable Crack Width

3. Properties of Section

As

1142

φ

16

mm

φ = Bar diameter.

s

175

mm

s = Spacing between steel bars.

50

mm

Cnom = Clear Nominal cover.

N/mm2

Ec = Modulus of elasticity of concrete.

Cnom

4. Calculations of crack width Ec

34000

n

12.35

dc

77.44

n = Es / (0.50*Ec) mm

dc = depth of concrete in compression.

7.922E+08

mm4

Inv = Moment of inertia of cracked section.

M

11.70

Kn.m

M = Total service bending moment.

σs

38.78

N/mm2

σs = Stress in tensile reinforcement.

εs ε1

1.85E-04

Inv

εs = Strain in tensile reinforcement. ε1 = Strain in concrete at tensile zone

2.45E-04

neg. concrete effect in tension.

εm

εm = Strain in tensile reinforcement at tensile zone

0.00E+00

Taking Stiffening of concrete in tension.

acr

96.98

mm

acr = distance from the crack point considered to the surface of nearest longitudinal bar.

Crack width = ( 3 *

09 Aug. 2010

acr * εc ) / (1 + 2 * ( acr-Cnom ) / ( h-dc )) =

0.000 mm Safe of crack width

Page 8 of 12


Flexural Capacity of Reinforced Concrete Rectangular Section According to BS 8110 Structural Design of Swimming Pools Part Title :- Design of Base Slab 1. Factored Bending Moments ( Kn,m ) 14

M ULT

Notations :

Kn.m

M ULT = Factored Bending Moment.

2. Properties of Concrete section & Steel

f cu cu

40

N/mm2

f cu cu = Compressive strength of concrete (Cube).

fy

420

N/mm2

f y = Yield strength of non-prestressing steel.

b

1000

mm

b = Width of rectangular section.

h

250

mm


d

170

mm

d = The effective depth to the tension reinforcement.

645

mm2

As = Total area of non-prestressing steel.

162

mm

z = The lever arm <= 0.95d.

As (T12-175)

3. Steps of Design

z Mu1

38

Kn.m


Mu2

173

Kn.m


38

Kn.m

Mu = The ultimate resistance moment.

375

mm2

Mu capacity As min.

09 Aug. 2010

Mu capacity

>

Mult

As provided is OK

As provided

>

As min.

As provided is OK

Page 9 of 12


Calculation of Crack Width According to BS 8110 ( Considering Stiffening Effect of The Concrete in Tension Zone ) Structural Design of Swimming Pools Part Title :- Design of Base Slab 1. Service Bending Moment ( Kn.m )

Notations :

M DL

6.90

Kn.m

M DL = Service bending moment due to dead load.

M LL

4.80

Kn.m

M LL = Service bending moment due to live load.

40

N/mm2

Fcu = Characteristic concrete cube strength.

210000

N/mm2

Es = Modulus of elasticity of steel.

2. Properties of Materials Fcu Es

0.20

mm

b

1000

mm

b = Width of section.

h

250

mm


d

170

mm

d = Effective depth to tension reinforcement.

As

645

mm2

As = Area of tension reinforcement.

φ

12

mm

φ = Bar diameter.

s

175

mm

s = Spacing between steel bars.

50

mm

Cnom = Clear Nominal cover.

N/mm2

Ec = Modulus of elasticity of concrete.

Allowable Crack Width

3. Properties of Section

Cnom

4. Calculations of crack width Ec

34000

n

12.35

dc

44.69

n = Es / (0.50*Ec) mm

dc = depth of concrete in compression.

1.549E+08

mm4

Inv = Moment of inertia of cracked section.

M

11.70

Kn.m

M = Total service bending moment.

σs

116.95

N/mm2

σs = Stress in tensile

εs ε1

5.57E-04

Inv

reinforcement.

εs = Strain in tensile reinforcement. ε1 = Strain in concrete at tensile zone

9.12E-04

neg. concrete effect in tension.

εm

εm = Strain in tensile reinforcement at tensile zone

4.21E-04

Taking Stiffening of concrete in tension.

acr

97.89

mm

acr = distance from the crack point considered to the surface of nearest longitudinal bar.

Crack width = ( 3 *

09 Aug. 2010

acr * εc ) / (1 + 2 * ( acr-Cnom ) / ( h-dc )) =

0.084 mm Safe of crack width

Page 10 of 12


5.

Check of Early Thermal Cracking Early thermal cracking shall be checked according to BD28. As = ( f ct ct / f b ) * Ac * φ * [R ( εsh + εth) - 0.5 * εult ] / ( 2 * w )

clause 5.3

f ct ct / f b = 0.67

clause 5.4.

Ac

= 250 * 1000 = 250000 mm2.

Gross area of section.

φ

= 12 mm

bar size.

R

= 0.50

Restraint Factor

εult

= 0.0002

clause 5.3

εsh

= 0.0001

clause 5.6

εth

= 0.80 * α * (T1 + T2)

clause 5.7

εth

= 0.80 * 0.000012 * (30 + 20) = 0.00048

w

= 0.20

allowable crack width

As required = 0.67 * 250000 * 12 * [ 0.50 * (0.0001 + 0.00048) - 0.5 * 0.0002 ] / ( 2 * 0.20 ) As required = 955 mm2. As provided = T12-175 at Top & Bottom Surface = 2 * 113 / 0.175 As provided = 1290 mm2 > A s required

09 Aug. 2010

OK

Page 11 of 12


6.

Check Soil Bearing Capacity Thickness of Plain concrete Slab

= 0.10 m.

Thickness of Reinforced Base Slab

= 0.25 m.

The maximum water depth

= 1.40 m.

Pressure on soil due to base slab and water

= 0.075 * 23 + 0.25 * 25 + 1.40 * 10 = 21.975 kN/m2.

Assuming the vertical wall weight shall acting on 1.00m width of base slab. Weight of vertical wall

= 0.36 * 1.60 * 25

= 14.40 kN/m’

Total pressure on the soil

= 21.98 + 14.40

= 36.38 kN/m2. = 0.36 kg/cm2.

09 Aug. 2010

Page 12 of 12

Structural Design of Swimming Pools

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