ANNEXURE -1
HYDRODYNAMIC FORCES CALCULATIONS
INPUT
2
Grade of Concrete fck = 30 N/mm
2
Grade of Reinforcement fy = 550 N/mm
Inside Diameter of Tank D = 32 m
Height of Slurry h = 8.5 m
Height of Tank H = 9 m
Thickness of Wall t = 0.35 m
3
Density of Slurry g=rg = 11 kN/m
Modulus of Elasticity of Concrete Ec = 27386128 kN/m2
Weight of Water inside Tank m = 75159.04 kN
Ratio of Height of water to Diamter h/D = 0.27
Calculation of Mass Coefficient
Ratio mi / m for h/D =0.27 mi / m = 0.3 Ref Fig 2a, IS 1893-2 :2014
Ratio mc / m for h/D =0.27 mc / m = 0.63 Ref Fig 2a, IS 1893-2 :2014
Factor kc hc / mg for h/D =0.27 kc hc/mg = 0.5 Ref Fig 2a, IS 1893-2 :2014
Hence, Convective mass mc = 4,645,054 kg
and Impulsive Mass mi = 2,211,931 kg
Calculation of Height Coefficient
Ratio hi / h for h/D =0.27 hi / h = 0.375 Ref Fig 2b, IS 1893-2 :2014
Ratio hc / h for h/D =0.27 hc / h = 0.52 Ref Fig 2b, IS 1893-2 :2014
Hence, Convective Height Coefficinet hc = 4.42 kN
and Impulsive Height Coefficinet hi = 3.1875 kN
Calculation of Time Period Coefficient
Ci for h/D =0.27 Ci = 5 Ref Fig 5, IS 1893-2 :2014
Cc for h/D =0.27 Cc = 3.8 Ref Fig 5, IS 1893-2 :2014
Time Period for Impulsive Mode of Vibration Ti = 0.258 Sec
Factor kc kc = 83406.13
Time Period for Convective Mode of Vibration Tc = 6.49 Sec
Calculation of Horizontal Seismic coefficient
Siesmic Zone = II
Zone Factor z = 0.1
Seismic Importance factor I = 1.5 Table-1, IS1893 Part-2:2014
Response Reduction factor R = 2.5 Table-3, IS1893 Part-2:2014
Type of Soil as per Table-1, IS1893 Part-1:2016 = Type B (Medium or Stiff) Check N Value
For Impulsive Mode of Acceleration
Type of Tank = Concrete Tank
Critical Damping = 5% Clasue 4.4, IS1893 Part-2:2014
Multiplying factor for Damping = 1 Clasue 4.5.2, IS1893 Part-2:2014
Impulsive Mass Time Period Ti = 0.258 Sec
Spectral Acceleration Coefficient Sa/g = 2.5
Hzl Seismic Acceleration Coeff for Impulsive Mode Ahi = 0.075 Ahi = Z/2 x I/R x Sa/g, Cl 4.5
Convective Mass Time Period Tc = 6.49 Sec
Critical Damping = 0.5% Clasue 4.4, IS1893 Part-2:2014
Multiplying factor for Damping = 1.75 Clasue 4.5.2, IS1893 Part-2:2014
Spectral Acceleration Coefficient Sa/g = 0.3
Hzl Seismic Acceleration Coeff for Impulsive Mode Ahc = 0.01575 Ahc= Z/2 x I/R x Sa/g, Cl 4.5
Equivalent Linear Pressure Distribution for Impulsive Mode
Base Shear due to Impulsive Liquid mass per unit Circumferential length is
qi = = 32.377 kN/m Clause 4.9.4, IS1893 Part-2:2014
Pressure at Bottom of Wall in impulsive mode ai = 6.67 kN/m2
Pressure at Top of Wall in impulsive mode bi = 0.96 kN/m2
Lateral impulsive Hydrodynamic pressure at BASE of wall Cl 4.9.1, IS1893 Part-2:2014
Coefficient of Impulsive Hydrodynamic Pressure =
At base of wall y= 0 Qiw = 0.864
Impulsive Hydrodynamic Pressure at base of wall, f =0 = 6.059 kN/m2
Lateral impulsive Hydrodynamic pressure at TOP of wall Cl 4.9.1, IS1893 Part-2:2014
Coefficient of Impulsive Hydrodynamic Pressure =
At base of wall y= 8.5 Qiw = 0
Impulsive Hydrodynamic Pressure at base of wall, f =0 = 0 kN/m2
Lateral Convective Hydrodynamic pressure at BASE of wall Cl 4.9.2, IS1893 Part-2:2014
Coefficient of Impulsive Hydrodynamic Pressure =
At base of wall y= 0 Qcw = 0.544
Impulsive Hydrodynamic Pressure at base of wall, f =0 = 2.011 kN/m2
Lateral Convective Hydrodynamic pressure at TOP of wall Cl 4.9.2, IS1893 Part-2:2014
Coefficient of Impulsive Hydrodynamic Pressure =
At base of wall y= 8.5 Qcw = 0.824
Impulsive Hydrodynamic Pressure at base of wall, f =0 = 3.046 kN/m2
