Experimental Study on the Fire-Induced Collapse of Single-Layer Aluminum Alloy Reticulated Shells with Gusset Joints

AbstractThis paper aims at investigating the fire-induced collapse behavior of aluminum alloy shells with gusset joints through an experimental analysis. The scale test model (geometric scaling coefficient=1/5) was composed of a K6 aluminum alloy spherical shell with a diameter of 8 m and a support structure with a height of 3.2 m. Diesel oil was used as the fuel, and the design power of the fire was 2 MW (corresponding to 111.8 MW of the prototype, calculated by the fire-power scaling law). Test results, including the test phenomenon, the failure mode, the thermal and structural response, and the deformation process, are presented and discussed. In the first fire test, the specimen did not collapse, and no permanent deformation, which would influence the mechanical behavior of the specimen, was observed. In the second fire test, the specimen began to collapse at 528 s, and the structural components failed by melting, rupture, and flexural-torsional buckling. While the members at the outside rings presented buckling, it is suggested that the thermal expansion be considered to prevent the buckling of the member in the structural fire design. Besides, the nonuniform temperature distribution was observed throughout the two structural fire tests, which confirmed that the homogeneous temperature assumption is not appropriate in analyzing large-space fires. Finally, the field simulation method to simulate the air temperature field of the tests is presented and verified, and the internal forces of members under nonuniform and uniform temperature distributions are compared. It is found that the field simulation can accurately evaluate the nonuniform air temperature distribution, and the nonuniform structural temperature distribution will significantly influence the internal forces of spherical shells. The experimental data and findings of this paper will be used for a further analysis of the structural fire behavior of aluminum alloy spatial structures.