{ "metadata": { "name": "", "signature": "sha256:bb71ed7156eb25f3e97cd3ba07ae31557b447cbcd71b351505ee32010461a02e" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 20: Structural idealization" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 20.1 Pg.No.560" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "sigma6=200\n", "sigma1=200\n", "sigma2=sigma5=150 #these are not real shear stress but taken \n", "sigma3=sigma4=100 #proportional to length because we need just ratio\n", "l16=400 \n", "t16=3\n", "l12=l21=600\n", "t12=t21=2 #thickness and lengths as shown in Fig 20.4\n", "l23=600\n", "t23=1.5\n", "l25=300\n", "t25=2.5\n", "l34=200\n", "t34=2\n", "#eqn 20.1 B1=t_D*b/6*(2+sigma_2/sigma_1)\n", "#eqn 20.2 B2=t_D*b/6*(2+sigma_1/sigma_2)\n", "B1=B6=300+l16*t16/6*(2-sigma6/sigma1)+l12*t12/6*(2+sigma2/sigma1)\n", "print \"B1=B6=%5.2f mm^2\\n\"%(B1)\n", "\n", "B2=B5=2*300+l12*t12/6*(2+sigma1/sigma2)+t25*l25/6*(2-sigma5/sigma2)+l23*t23/6*(2+sigma3/sigma2)\n", "print \"B2=B5=%5.2f mm^2\\n\"%(B2)\n", "\n", "B3=300+l23*t23/6*(2+sigma2/sigma3)+l34*t34/6*(2-sigma4/sigma3)\n", "print \"B3=B4=%5.2f mm^2\\n\"%(B3)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "B1=B6=1050.00 mm^2\n", "\n", "B2=B5=1791.67 mm^2\n", "\n", "B3=B4=891.67 mm^2\n", "\n" ] } ], "prompt_number": 10 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 20.2 Pg.No.562" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "Mx=100*10**6 #bending moment(N.mm)\n", "y=[660,600,420,228,25,-204,-396,-502,-540]\n", "B=[640,600,600,600,620,640,640,850,640]\n", "\n", "print \"direct stress in each boom in last column\"\n", "print \"Boom\\t y(mm)\\t B(mm^2)\\t delIxx=By^2\\t sigma_z\"\n", "for i in range (0,9):\n", " print \"%1.0f \\t %3.0f \\t %3.0f \\t \\t%2.1e \\t %2.1f\"%(i+1,y[i],B[i],B[i]*y[i]**2,Mx*y[i]/(1854*10**6))" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "direct stress in each boom in last column\n", "Boom\t y(mm)\t B(mm^2)\t delIxx=By^2\t sigma_z\n", "1 \t 660 \t 640 \t \t2.8e+08 \t 35.6\n", "2 \t 600 \t 600 \t \t2.2e+08 \t 32.4\n", "3 \t 420 \t 600 \t \t1.1e+08 \t 22.7\n", "4 \t 228 \t 600 \t \t3.1e+07 \t 12.3\n", "5 \t 25 \t 620 \t \t3.9e+05 \t 1.3\n", "6 \t -204 \t 640 \t \t2.7e+07 \t -11.0\n", "7 \t -396 \t 640 \t \t1.0e+08 \t -21.4\n", "8 \t -502 \t 850 \t \t2.1e+08 \t -27.1\n", "9 \t -540 \t 640 \t \t1.9e+08 \t -29.1\n" ] } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 20.3 Pg.No.566" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "Ixx=48*10**6\n", "Sy=4.8*10**3\n", "B=300\n", "\n", "q12=-Sy/Ixx*B*200 #until point 2 \n", "q23=q12-Sy/Ixx*B*200\n", "q34=q23-Sy/Ixx*B*(-200)\n", "print \"shear flow in flange 12 = %2.0f N/mm\\n\"%(q12)\n", "print \"shear flow in web 23 = %2.0f N/mm\\n\"%(q23)\n", "print \"shear flow in flange 34 = %2.0f N/mm\\n\"%(q34)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "shear flow in flange 12 = -6 N/mm\n", "\n", "shear flow in web 23 = -12 N/mm\n", "\n", "shear flow in flange 34 = -6 N/mm\n", "\n" ] } ], "prompt_number": 17 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 20.4 Pg.No.569" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "B=[200,250,400,100,100,400,250,200]\n", "Ixx=13.86*10**6\n", "Sy=10*10**3\n", "qb23=0\n", "qb34=qb23-Sy/Ixx*B[2]*100\n", "qb45=qb34-Sy/Ixx*B[3]*50\n", "qb56=qb34\n", "qb67=qb23\n", "qb21=qb67-Sy/Ixx*(B[1]*100)\n", "qb18=qb21-Sy/Ixx*B[7]*30\n", "qb87=qb21\n", "qs0=-5.4\n", "print \"Distribution of shear flow :\"\n", "print \"q23 = %2.1f N/mm\"%(qb23+qs0)\n", "print \"q21 = %2.1f N/mm\"%(qb21-qs0)\n", "print \"q34 = %2.1f N/mm\"%(qb34-qs0)\n", "print \"q45 = %2.1f N/mm\"%(qb45-qs0)\n", "print \"q56 = %2.1f N/mm\"%(qb56-qs0)\n", "print \"q67 = %2.1f N/mm\"%(qb67+qs0)\n", "print \"q18 = %2.1f N/mm\"%(qb18-qs0)\n", "print \"q87 = %2.1f N/mm\\n\"%(qb87-qs0)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Distribution of shear flow :\n", "q23 = -5.4 N/mm\n", "q21 = -12.6 N/mm\n", "q34 = -23.5 N/mm\n", "q45 = -27.1 N/mm\n", "q56 = -23.5 N/mm\n", "q67 = -5.4 N/mm\n", "q18 = -17.0 N/mm\n", "q87 = -12.6 N/mm\n", "\n" ] } ], "prompt_number": 28 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 20.5 Pg.No.575" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "from sympy import symbols, integrate\n", "z=symbols('z')\n", "\n", "E=70000 #youngs modulus (N/mm^2)\n", "G=30000 #shear modulus (N/mm^2)\n", "P=4.8*10**3 #applied force (N)\n", "L=2000 #cantilever length(mm)\n", "Sy=P\n", "Ixx=48*10**6 #second moment of area \n", "t=1 #actual thickness (mm)\n", "\n", "Mx0=-Sy*(L-z)\n", "Mx1=-(L-z)\n", "\n", "del_M=integrate(Mx0*Mx1/E/Ixx,(z,0,L))\n", "del_S=integrate((1/G/t/Sy*(6**2*200+12**2*400+6**2*200)),(z,0,L))\n", "print \"total deflection in vertical direction = %1.2f mm\\n\"%(del_M+del_S)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "total deflection in vertical direction = 4.81 mm\n", "\n" ] } ], "prompt_number": 36 }, { "cell_type": "code", "collapsed": false, "input": [], "language": "python", "metadata": {}, "outputs": [], "prompt_number": 35 } ], "metadata": {} } ] }