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The Problem. Sines and Cosines. sin a 1 = (-12 - 0) / (20) = -0.6 cos a 1 = (16 - 0) / (20) = 0.8 sin a 2 = (12 - 0) / (15) = 0.8 cos a 2 = (9 - 0) / (15) = 0.6 . Element Matrices [S]. 3 4 1 2. 1 2 5 6. System Stiffness Matrix.
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Sines and Cosines sina1 = (-12 - 0) / (20) = -0.6 cosa1 = (16 - 0) / (20) = 0.8 sina2 = (12 - 0) / (15) = 0.8 cosa2 = (9 - 0) / (15) = 0.6
Element Matrices [S] 3 4 1 2 1 2 5 6
Element Matrices [S] 3 4 1 2 1 2 5 6
Two Matrix Contributions 1 2 3 4 5 6
Final [K] 1 2 3 4 5 6
Solution 10 = AE/L X1 100 = AE/L X2 0 = AE/L X3 0 = AE/L X4 0 = AE/L X5 0 = AE/L X6
Force Calculation (f=sbX) {(X3i-X1i) cosai + (X4v-X2v) sinai} is simply the change in length t1 = AE/L {(10L/AE - 0)(0.8) + (100L/AE - 0)(-0.6)} + (0) t2 = AE/L {(0 - 10L/AE - 0)(0.6) + (0 - 100L/AE - 0)(0.8)} + (0) t1 = f2 = -f1 = -52 kips t2 = f4 = -f3 = -86 kips