申論題

(20%) 2. A two-story building has steel columns AB in the first floor and BC in the second floor. The roof load P₁ equals 400 kN and the second-floor load P₂ equals 720 kN. Each column has length L = 3.75 m. The cross-sectional areas of the first- and second-floor columns are 11,000 mm²and 3900 mm², respectively.

(a) Assuming that E= 206 GPa, determine the total shortening of the two column nns due to the combined action of the loads P₁and P₂. (10%)