Problem $5$

A cylindrical steel column is built by joining together the three cylindrical steel elements $AB,BC,$ and $),$ and restrained by rigid supports at A and D as shown in the figure. The member is subjected to axial force of $100$ kN at point B$.$ Determine the following:

a$)$ the reaction at A and $D$

b$)$ The normal stress in the middle of rod $AB$ and $CD($indicate whether tension or compression$)$

please solve and help me understand