{ "metadata": { "name": "", "signature": "sha256:540962ba0b5999b583f0620c9dca124d46f25fe569649c6c842d96cfa42351a3" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 3: Static Forces on Surfaces. Buoyancy" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.1, Page 65" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", " #Initializing the variables\n", "a = 2.7; #Upper edge\n", "b = 1.2 ; #Lower edge\n", "width = 1.5; #Width of trapezoidal plate\n", "h = 1.1; #Height of water column above surface\n", "rho = 1000;\n", "g = 9.81 #Acceleration due to gravity\n", "phi = 90 #Angle between wall and surface\n", "\n", " #Calculations\n", "A = 0.5*(a+b)*width; #Area of Trapezoidal Plate\n", "y = (2*(0.5*width*0.75)*0.5 + (1.2*width)*0.75)/A;\n", "z = y+h; #Depth of center of pressure\n", "R = rho*g*A*z #Resultant force\n", "\n", "I0 = 1.2*1.5**3/12 +1.2*1.5*1.85**2 + 1.5*1.5**3/36 + 1.5*0.75*1.6**2 #Second moment of area\n", "D = (math.sin(math.degrees(phi)))**2*I0/(A*z); #depth of center of pressure\n", "M = R*(1.8533-1.1); #Moment about hinge\n", "print \"Moment about the hinge line (kN/m):\",round(M/1000)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Moment about the hinge line (kN/m): 38.0\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.2, Page 67" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", " #Initializing the variables\n", "w = 1.8; #Width of plate\n", "h1 = 5; #Height of plate and water in upstream\n", "h2 = 1.5; #Height of water in downstream\n", "rho = 1000;\n", "g = 9.81 ; #Acceleration due to gravity\n", "\n", " #Calculations\n", "def waterForce(area,meanHeight):\n", " F = rho * g * area * meanHeight;\n", " return F\n", "\n", "P = waterForce(w*h1,h1/2)-waterForce(w*h2,h2/2);# Resultant force on gate \n", "x = (waterForce(w*h1,h1/2)*(h1/3) - waterForce(w*h2,h2/2)*(h2/3))/P;# point of action of p from bottom\n", "R = P/(2*math.sin(math.radians(20))); # Total Reaction force\n", "Rt = 1.18*R/4.8; #Reaction on Top\n", "Rb = R - Rt ; #Reaction at bottom\n", "\n", "print \"Reaction at top (kN):\",round(Rt/1000,1)\n", "print \"Reaction at bottom (kN):\",round(Rb/1000,2)\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Reaction at top (kN): 72.2\n", "Reaction at bottom (kN): 221.45\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.3, Page 70" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "\n", "\n", " #Initializing the variables\n", "D = 1.8; #Depth of tank\n", "h = 1.2; #Depth of water\n", "l = 3; #Length of wall of tank\n", "p = 35000; #Air pressure\n", "rho = 10**3; #Density of water\n", "g = 9.81; #Acceleration due to gravity\n", "\n", "\n", " #Calculations\n", "Ra = p*D*l; #Force due to air\n", "Rw = .5*(rho*g*h)*h*l; #Force due to water\n", "R = Ra + Rw; # Resultant force\n", "x = (Ra*0.9+Rw*0.4)/R; # Height of center of pressure from base\n", "print \"Resultant force on the wall (kN) :\",round(R/1000,2)\n", "print \"Height of the centre of pressure above the base (m) :\",round(x,2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Resultant force on the wall (kN) : 210.19\n", "Height of the centre of pressure above the base (m) : 0.85\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.4, Page 72" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", " \n", "\n", " #Initializing the variables\n", "R = 6; # Radius of arc\n", "h = 2*R*math.sin(math.radians(30)); #Depth of water\n", "rho = 10**3; #Density of water\n", "g = 9.81; #Acceleration due to gravity\n", "\n", " #Calculations\n", "Rh = (rho*g*h**2)/2; # Resultant horizontal force per unit length\n", "Rv = rho*g*((60/360)*math.pi*R**2 -R*math.sin(math.radians(30))*R*math.cos(math.radians(30)));# Resultant vertical force per unit length\n", "R = (Rh**2+Rv**2)**0.5; # Resultant force on gate\n", "theta = 180/math.pi*math.atan(Rv/Rh); #Angle between resultant force and horizontal\n", "\n", "print \"Magnitute of resultant force (kN/m) :\",round(R/1000,2)\n", "print \"Direction of resultant force to the horizontal(Degrees):\",round(theta,2)\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Magnitute of resultant force (kN/m) : 179.45\n", "Direction of resultant force to the horizontal(Degrees): 10.27\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.5, Page 75" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", " #Initializing the variables\n", "B = 6; # Width of pontoon\n", "L = 12; #Length of pontoon\n", "D = 1.5; #Draught of pontoon\n", "Dmax = 2; #Maximum permissible draught\n", "rhoW = 1000; #Density of fresh water\n", "rhoS = 1025; #Density of sea water\n", "g = 9.81; #Acceleration due to gravity\n", "\n", " #Calculations\n", "def Weight(D):\n", " W = rhoW*g*B*L*D;\n", " return W\n", "\n", "W = Weight(D); # Weight of pontoon in fresh water = weight of water displaced\n", "Ds = W/(rhoS*g*B*L); #Draught in sea water\n", "L = Weight(Dmax) - Weight(D); # maximum load that can be supported\n", "\n", "print \"Weight of pontoon (kN) :\",round(W/1000,1)\n", "print \"Draught in sea (m) :\",round(Ds,2)\n", "print \"Load (kN) :\",round(L/1000,2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Weight of pontoon (kN) : 1059.5\n", "Draught in sea (m) : 1.46\n", "Load (kN) : 353.16\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.6, Page 80" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "\n", "\n", " #Initializing the variables\n", "D = 1.8; # Diameter of buoy\n", "H = 1.2; #Height of buoy\n", "W = 10*10**3; #Weight of buoy\n", "L = 2*10**3; #Load\n", "G = 0.45; # Center of gravity\n", "rho = 1025; #Density of sea water\n", "g = 9.81; #Acceleration due to gravity\n", "\n", " #Calculations\n", "Z = 4*(W+L)/(rho*g*math.pi*D**2); # Depth of Immersion\n", "BG = (math.pi*D**4/64)/(math.pi*D**2*Z/4);\n", "Z = 0.5*Z +BG; # Position of combined center of gravity\n", "Z1 = ((W+L)*Z-0.45*W)/L; #Maximum height of load above bottom\n", "\n", "print \"Maximum height of center of gravity above bottom (m) :\",round(Z1,3)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Maximum height of center of gravity above bottom (m) : 1.748\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3.7, Page 83" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", " #Initializing the variables\n", "l = 20; # Length of barage\n", "b = 6; #Width of barage\n", "r = 3; #Radius of circular top of barage\n", "W = 200*10**3; #Weight of empty barage\n", "d1 = 0.8; # Depth of water in 1st half\n", "d2 = 1; # Depth of water in 2nd half\n", "rho = 1000; #Density of water\n", "R = 0.8; #Relative density of liquid\n", "g = 9.81; #Acceleration due to gravity\n", "ZG = 0.45; # Center of gravity of barage\n", "\n", " #Calculations\n", "I00 = l*b**3/12 +math.pi*b**4/128;\n", "ICC = l*(.5*b)**3/12;\n", "L = d1*rho*g*l*b/2*(d1+d2); # Weight of liquid load\n", "W = L + W; #Total weight\n", "A = l*b +math.pi*r**2/2; # Area of plane of waterline\n", "V = W/(rho*g); # Volume of vessel submerged\n", "D = V/A ; #Depth submerged\n", "ZB = .5*D; #Height of center of buoyancy\n", "NM = ZB-ZG +(1/V)*(I00-R*2*ICC); # Effective metacentric height\n", "P = R*rho*g*l*b/2*(d2-d1); #overturning moment \n", "theta = math.atan(P*1.5/(W*NM))*180/math.pi; #Angle of roll\n", "# converting into degrees and minutes\n", "thetaD=round(theta-1)\n", "thetaM=(theta-thetaD)*60/100\n", "print \"Angle of roll is\",thetaD,\"degrees\",round(thetaM,2),\"minutes\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Angle of roll is 2.0 degrees 0.37 minutes\n" ] } ], "prompt_number": 7 } ], "metadata": {} } ] }