Strap Footing
6
Design of strap footing 1 - Iinput data Name of project Type of project 1 Dwelling Type of building 1 Without basement 4.6 2 - Properties of columns a - Exterior column Total load ( ton ) 55 Length in direction of footing ( cm ) 30 Breadth in perpendicular direction ( cm ) 50 0 The distance equal zero 0 m 0 a -Interior column Total load ( ton ) 135 Length in direction of footing ( cm ) 70 Breadth in perpendicular direction ( cm ) 30 2 0 m 0.85 q all. soil 15 t / m2 Total depth of plain concrete 30 cm 3 - Dimension of isolating footing a - Exterior footing 1.5 Aproximate Be ( m ) 2.2 0.60 Re under P.C ( t ) 69.58 Area plain concrete ( m2 ) 4.64 Be plain concrete ( m ) 1.5 Ae plain concrete ( m ) 3.1 Be reinf. concrete ( m ) 1.2 Ae reinf. concrete ( m ) 2.5 Re under R.C ( t ) 60.96 We ( t / m ) 20.32 b - Interior footing 3 Aproximate Bi ( m ) 3.4 0.00 RI under P.C ( t ) 148.50 Area plain concrete ( m2 ) 10.20 Bi plain concrete ( m ) 3.00 Ai plain concrete ( m ) 3.40 Bi reinf. concrete ( m ) 2.40 Ai reinf. concrete ( m ) 2.80 Ri under R.C ( t ) 129.04 Wi ( t / m ) 19.20 4 - Design of footing fc ( kg / cm2 ) 250 fs ( kg / cm2 ) 1400 K1 0.313 K2 1217 1 - Iinput data / ور ك ش ل دا ب ع م ي هرا ب ا سThe distance between center line of columns( m ) The limit of distance between edge of column and edge of R.C footing The distance between edge of column and edge of R.C footing ( m ) The limit of distance between edge of column and edge of R.C footing The distance is no limited The distance between edge of column and edge of R.C footing ( m ) Assuming breadth of plain footing in strap direction Be ( m ) The distance between center of column and center of P.C footing in strap direction e ( m ) Assuming breadth of plain footing in strap direction BI ( m ) The distance between center of column and center of P.C footing in strap direction e ( m ) 5.96 15.61 21.17 7.16 -17.34 -38.71 -19.42 B . M . Diagram -39.76 -24.52 5.96 5.96 51.66 -64.52 -45.70 S . F . Diagram
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Transcript of Strap Footing
Design of strap footing1 - Iinput dataName of project
Type of project 1 Dwelling Type of building 1 Without basement
The distance between center line of columns( m ) 4.6
2 - Properties of columnsa - Exterior columnTotal load ( ton ) 55Length in direction of footing ( cm ) 30Breadth in perpendicular direction ( cm ) 50
0 The distance equal zero 0 m
0
a -Interior columnTotal load ( ton ) 135Length in direction of footing ( cm ) 70Breadth in perpendicular direction ( cm ) 30
2 The distance is no limited 0 m
0.85
q all. soil 15 t / m2
Total depth of plain concrete 30 cm
3 - Dimension of isolating footinga - Exterior footing
1.5 Aproximate Be ( m ) 2.2
0.60
Re under P.C ( t ) 69.58Area plain concrete ( m2 ) 4.64
Be plain concrete ( m ) 1.5Ae plain concrete ( m ) 3.1Be reinf. concrete ( m ) 1.2Ae reinf. concrete ( m ) 2.5
Re under R.C ( t ) 60.96 We ( t / m ) 20.32
b - Interior footing
3 Aproximate Bi ( m ) 3.4
0.00
RI under P.C ( t ) 148.50Area plain concrete ( m2 ) 10.20
Bi plain concrete ( m ) 3.00Ai plain concrete ( m ) 3.40Bi reinf. concrete ( m ) 2.40Ai reinf. concrete ( m ) 2.80
Ri under R.C ( t ) 129.04 Wi ( t / m ) 19.204 - Design of footing
fc ( kg / cm2 ) 250fs ( kg / cm2 ) 1400
K1 0.313K2 1217
1 - Iinput data
عبد / إبراهيم مهندسالشكور
The limit of distance between edge of column and edge of R.C footing
The distance between edge of column and edge of R.C footing ( m )
The limit of distance between edge of column and edge of R.C footing
The distance between edge of column and edge of R.C footing ( m )
Assuming breadth of plain footing in strap direction Be ( m )
The distance between center of column and center of P.C footing in strap direction e ( m )
Assuming breadth of plain footing in strap direction BI ( m )
The distance between center of column and center of P.C footing in strap direction e ( m )
5.9615.61
21.17
7.16
-17.34
-38.71
-19.42
B . M . Diagram
-39.76-24.52
5.96 5.96
51.66
-64.52
-45.70
S . F . Diagram
B4
1- dwelling 2 - office building 3- halls 4- school 5- hospital
B5
0- basement 1- without basement
B12
0- the distance =0 1- the distance = limited number 2- the distance =any number( .5 m )
G12
The distance can be assumed
B18
0- the distance =0 1- the distance = limited number 2- the distance =any number( .5 m )
G18
The distance can be assumed
Name of projectType of project 1 Dwelling Type of building 1 Without basement a - Exterior footing
M 1 - 1 17.49M 2 - 2 10.36d ( cm ) 38
Total depth of reinforced concrete ( cm ) 48Assuming total depth ( cm ) 70
a - Transverse ( Reinf. )As ( cm2 ) 13.52 7 F 16 13.52 OK
As min . ( cm2 ) 12.60 6 F 16 12.60 Take min. reinf.b - Longitudinal ( Reinf. )
As ( cm2 ) 22.8 13 F 16 25.12 Take min. reinf.As min . ( cm2 ) 26.3 13 F 16 26.25 OK
b - Interior footingM 1 - 1 16.51M 2 - 2 23.70d ( cm ) 29
Total depth of reinforced concrete ( cm ) 39Assuming total depth ( cm ) 60
a - Transverse ( Reinf. )As ( cm2 ) 36.7 18 F 16 36.74 OK
As min . ( cm2 ) 21.60 19 F 12 21.60 Take actual reinf.b - Longitudinal ( Reinf. )
As ( cm2 ) 25.6 12 F 18 30.48 OK As min . ( cm2 ) 25.2 22 F 12 25.20 Take actual reinf.
5 - Design of Strap beamPe ( t / m ) 50.80Pi ( t / m ) 53.77M (m.t ) 38.71b ( cm ) 70.00d (cm ) 62 80
a - As Upper ( cm2 ) 23.68 6 F 22 23.68 OK 2 F 16 4.68
OK Bent bars 5 F 22 19.00
b - As Lower ( cm2 ) 43.30 9 F 25 43.30 OK As min . ( cm2 ) 8 4 F 16 8.04 Take actual reinf.
c - StirrupsNumber of stirrups / m 7 f 10
Number of branchs 46 - Check of shear
Qmax ( t ) 13.72 17.20 64.52
qsh ( kg / cm2 ) 0.9 1.2 14 OK OK Unsafe
7 - check of punchingQp ( t ) 40.88 115.40
qp ( kg / cm2 ) 1.6 4.4 OK OK
8 - Final solutionA - Isolated footing b - Interior footing
Total depth 70 cm 60 cmLength of plain footing ( m ) 1.5 m 3.00 mBreadth of plain footing ( m ) 3.1 m 3.4 m
Length of reinforced footing ( m ) 1.2 m 2.40 mBreadth of reinforced footing ( m ) 2.5 m 2.80 m
Transverse reinforced 7 F 16 18 F 16 Longitudinal reinforced 13 F 16 12 F 18
B - Strap beamTotal depth 80 cm
As Upper ( cm2 ) 6 F 22Straight bars 2 F 16
Bent bars 5 F 22 As Lower ( cm2 ) 9 F 25
Stirrups 7 f 10 4 branchs
Total debth
Straight bars
a - Exterior footing
B54
1- dwelling 2 - office building 3- halls 4- school 5- hospital
B55
0- basement 1- without basement
B95
Q - for ext. footing
E95
Q - for int. footing
H95
Q - for strap
B96
q - for ext. footing
E96
q - for int. footing
B99
Q - for ext. footing
F99
Q - for int. footing
B100
q - for ext. footing
F100
q - for int. footing
Check for shear for strap beam
Name of project 0
Type of project 1 Dwelling
Type of floor 1 Without basement
Shear force on support 64.52 ton
Moment on support 0 t.m
fs ( kg / cm2 ) 1400
C28 ( kg / cm2 ) 250 fc 90 kg / cm2
b ( cm ) 70
t ( cm ) 80
7
19
Q ( Max . ) 64.52 ton
Moment 38.71 t.m
Angle of inclined 0 OK
14 Use stirrup and bent bar
10.5 kg / cm2
Number of stirrups 7 S 14.3 cm
Diameter of stirrups 10 n 4
4.4
Number of bent bars 5 a 60
Diameter of bent bars 22
4.4
( q st + q sb ) 8.8 Unsafe
( Change the stirrups or bent bars )
الشكور / عبد ابراهيم م .تصميم
q c
q 2
q ( Max . ) kg / cm2
q s
q st kg / cm2
q sb kg / cm2
kg / cm2
Return
B3
1 - dwelling 2 - office building 3 - hospital 4 - hall 5 - school
B4
0 - Basement 1 - Flour 2 - Roof
A12
Concrete shear strength without reinf.
A13
Max. shear stress ( Allowable ) using reinf.
A18
q = Qmax/(.87*b*d )
A19
The shear stress resisted by web reinf. ( stirrups + bent bar )
D21
pitch between stirrup
D22
number of branchs
A23
the shear stress risisted by stirrup
E25
angle of bent bar
A27
the shear stress risisted by bent bars
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