47 opposite therefrom on the circles other side is a similar tri axial connector 49 which joins the two horizontal frame sections 29 and 31 to each other and the vertical section 34 at their interlocking zenith interface 51 the two curved joined frame sections 33 and 34 are joined together by a cotter type securing pin 53 which extends through a horizontal hole not shown in both sections ends fig5 is an enlarged view of one of the rivet mounted bracket 55 having a female type slotted connector 57 fixed to it this connector extends outward from the circle formed by the four frame sections members and has two separate three sided legs 59 and 61 these legs are shaped and sized to slidably engage the i beam shaped male extender 21 by sliding down into them by providing less taper to the connector 39 s legs than the extender 21 the connector binds when slides down on the extender and is prevented it from falling through it this assures a firm hold between the extender and connector alternately an internal stop not shown in the extender 39 s i beam slot could be used to prevent the legs 59 and 61 from falling through and act to vertically support the frame connection the covering 5 used to cover the assembled frame.