A hollow circular steel column is subjected to a compression load of 380KN. The column has a length of 2.4m and an outside diameter of 187.5mm. (a.)Compute the minimum required wall thickness based on an allowable compressive stress of 48MPa. (b.)If wall thickness is 20mm and allowable compressive stress is 50MPa, compute the allowable compression load.

1- Daw the strain and stress diagrams for untracked plain concrete shown below. Developed the tension and compression expressions? Materials are given as: f'c=X1 MPa, fr=0.07X1 MPa X1=72.1 X2=620.4 X3=144.2 X3 mm 1- Consider a rectangular column subjected to axial compression. The material stress-strain relationships have been idealized as shown below. a) What axial load will cause concrete to be at its maximum working stress? b) find the axial load P which produces & = & = 0.0012 1.75 X3