2.矩形混凝土橋墩的高度20m，斷面1.2m×0.5m，混凝土的彈性模數E=28GPa。若不考慮橋墩自重，在橋墩上施加400kN載重於斷面形心時，橋墩的高度會縮短多少距離？(25分)

2. A pressurized cylindrical tank with flat ends is loaded by torques T and tensile forces P as shown in Fig. 2. The tank has inner radius of r = 125 mm and wall thickness t = 6.5 mm. The internal pressure p = 7.25 MPa and the torque T = 850 N-m. What is the maximum permissible value of the forces P if the allowable tensile stress in the wall of the cylinder is 80 MPa? (20%)Fig. 2