CE 415 Design of steel structures

CE 318

STRUCTURE ANALYSIS AND DESIGN II LAB

LESSON 11

UNDERGROUND WATER RESERVOIR (CONTD.)

SEMESTER: SUMMER 2021

COURSE TEACHER: SAURAV BARUA CONTACT NO: +8801715334075

EMAIL: saurav.ce@diu.edu.bd

LECTURE PLAN

Side walls

Horizontal and vertical rebar calculation

Detailing of water reservoir

SIDE WALL DESIGN

Vertical rebar:

H = 8.83’

Vertical cantilever, h = H/4 = 2.21’ . if h<3’, h = 3’.

h = H/4 ≥ 3’

H-h = 8.83- 3 = 5.83’

Ø = 30°

Active earth pressure, k_a = (1-sin Ø)/(1+sin Ø) = 0.33

g = g_w + k_a (g_{ws –} g_w)

= 62.4 + 0.33 x (120-62.4)

= 81.6 pcf

MOMENT FOR VERTICAL REBAR

Mu = g H h²/6

= 81.6 x 8.83 x 3²/6

= 1080.8 lb-ft/ft

= 1.08 k-ft/ft

As = Mu / Ø fy (d-a/2) a = As fy/(0.85 fc’ x b)

d = 9-1.5 = 7.5” and assume, a =1”

As = 1.08 x 12/ (0.9 x 60 x (7.5-a/2))

= 0.034 in²/ft

VERTICAL REBAR

a = 0.034 x 60/(0.85 x 3 x12)

= 0.07 in

Retrial, As = 0.034 x 12/ (0.9 x 60 x (7.5-0.07/2))

= 0.001 in²/ft

As_temp = 0.0018 bh = 0.0018 x 12 x 9 = 0.19 in²/ft Provide Ø12mm bar

Spacing = 0.2 x 12/0.19 ≈ 12” c/c

Provide Ø12mm @ 12” c/c in long as well as short wall

SIDE WALL HORIZONTAL REBAR

LONG WALL MOMENT

Horizontal rebar of long wall

Long wall horizontal moments, Mu = ± PL²/14 P = g (H-h) = 81.6 x (8.83-3)

= 475.73 psf = 0.48 ksf

Long wall horizontal moments, Mu = ± 0.48 x 12²/14

= ± 4.93 k-ft/ft

HORIZONTAL REBAR OF LONG WALL

As = Mu / Ø fy (d-a/2) a = As fy/(0.85 fc’ x b)

d = 9-1.5 = 7.5” and assume, a =1”

As = 4.93 x 12/ (0.9 x 60 x (7.5-a/2))

= 0.16 in²/ft

HORIZONTAL REBAR OF LONG WALL

a = 0.16 x 60/(0.85 x 3 x12)

= 0.31 in

Retrial, As = 0.16 x 12/ (0.9 x 60 x (7.5-0.31/2))

= 0.004 in²/ft

As_temp = 0.0018 bh = 0.0018 x 12 x 9 = 0.19 in²/ft Provide Ø10mm bar

Spacing = 0.11 x 12/0.19 = 6.5” c/c

Provide Ø10mm @ 6.5” c/c in horizontal bar of long wall

SHORT WALL MOMENT

Horizontal rebar of short wall

Long wall horizontal moments, Mu = ± PB²/14 P = g (H-h) = 81.6 x (8.83-3)

= 475.73 psf = 0.48 ksf

short wall horizontal moments, Mu = ± 0.48 x 6²/14

= ± 1.23 k-ft/ft

HORIZONTAL REBAR OF LONG WALL

As = Mu / Ø fy (d-a/2) a = As fy/(0.85 fc’ x b)

d = 9-1.5 = 7.5” and assume, a =1”

As = 1.23 x 12/ (0.9 x 60 x (7.5-a/2))

= 0.04 in²/ft

HORIZONTAL REBAR OF LONG WALL

a = 0.04 x 60/(0.85 x 3 x12)

= 0.08 in

Retrial, As = 0.04 x 12/ (0.9 x 60 x (7.5-0.08/2))

= 0.001 in²/ft

As_temp = 0.0018 bh = 0.0018 x 12 x 9 = 0.19 in²/ft Provide Ø10mm bar

Spacing = 0.11 x 12/0.19 = 6.5” c/c

PLAN REBAR OF UGWR

CROSS SECTION OF UGWR