The paper discusses labroatory tests and the comparative ultimate loads and stiffnesses resulting from the shaping of two different layouts of steel chord members from an initally flat condition to a gently curved domical shape (ie., with positive Gussian curvature). Two trusses have out-of-plane web members in all panesl, and two trusses have out-of-plane web mebers located only at the periphery of the trusses. The shaping operation in each case is carried out by a post-tensioning operation. Ultimate load tests on models of about 3m span are described, and the overall responses of the four tests are discussed and compared. It is shown that the use of out-plane-web members enhances considerably the ultimate load capacity and stiffness of the two shaped trusses when compared with the same layerouts withoug internal web members. In each case the shaping operation is able to be carried out readily.
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