| 摘要 |
<p>The transversely-extending bars (16, 18) of the structure are all joined to the longitudinally-extending bars (12, 14) to occupy a first plane, one longitudinally-extending bar is disposed in a second plane laterally of the first plane, and the other longitudinally-extending bar is disposed in a third plane laterally of the first plane on the other side of the second plane, such as to permit a plurality of such trusses to be nested together with the transversely-extending bars of all the trusses disposed in the first plane, and the longitudinally-extending bars of all the trusses disposed in the second and third planes.</p> |
