| The purpose of this research was to obtain a better understanding of the diaphragm action of cladding and its effects on the deflections and load paths in typical low-rise metal buildings. This study consisted of a series of full-scale dynamic tests to determine the structural characteristics of an actual building. Data obtained from these tests were then used to verify a computer model of the structure. The model consisted of all the components used in the actual structure, with the corrugated cladding panels being modeled as orthotropic plates of uniform thickness with reduced shear rigidity. The detailed analysis using the computer model showed a large degree of load sharing among the frames under the action of wind loads. In the transverse direction, the roof and end-wall cladding transferred the loads from the interior frames, thus reducing the forces carried by the interior frames and their subsequent displacements. Since there were no cross-bracings in the structure, the side walls provided the majority of the stiffness in the longitudinal direction.; Observations and results obtained from the above studies were implemented in a spring model to be used as a tool to predict deflections and load paths at the design stage. The spring stiffness of the substructures can be determined by analytical methods. The spring model also revealed that the load transfer due to diaphragm action of the cladding is more pronounced in buildings with less than eight frames. Since the interior frames in short buildings are not carrying the lateral loads assumed in their design, it would be economically beneficial to reduce the size of those frames, consistent with the loads they actually carry, without affecting the structural integrity of the building system. However, there is very little information available on the capacity of the cladding and the fasteners to resist uplift and in-plane loads. This information is necessary before any benefit of diaphragm action can be utilized in design. |
