5. A double riveted lap joint with chain riveting is to be made for joining two plates 10 mm thick. The allowable stresses are: σ, 60 MPa;t=50 MPa and σ -80 MPa. Find the rivet diameter, pitch of rivets and distance between rows of rivets. Also find the efficiency of the joint. [Ans. d=20 mm; p=73 mm; p=38 mm; n = 71.7%]