Barari Reshtehroudi, MohammadMahdi
(2022)
Structural behaviour of bending active structures. The impact of load distribution, geometry, temperature and wind loads on the structural performance.
PhD thesis, University of Nottingham.
Abstract
With the advanced development and growth of engineering in the construction industry, the use of lightweight structures has received a significant amount of attention due to their advantages, such as lightness, portability and multi-purpose uses. Therefore, new ideas and methods in design and construction have gained popularity in the building sector. The development of the Bending Active Theory played a crucial role in this process and, therefore, this study includes detailed descriptions of its historical evolution and the mathematical and structural theories behind its use in the building sector. As the existing studies mainly focused on architectural aspects, this research aimed to provide a better understanding of the structural behaviour of bending active structures under both internal stresses created due to bending and external loadings and investigate the impact of environmental temperature and lateral force for design and construction using laboratory tests and numerical modelling. Geometry, length, and cross-section are among the essential factors in the structural behaviour of bending active structures that their effects were also studied in this research.
The findings indicated that as a high f/L ratio could increase the deformations and cause the instability of the structure, the f/L ratio of up to 0.7 was recommended for bending active structures. As well as the effect of cross-sections on stress distribution, the orientation and angle of the component to which bending was applied significantly affected the level of stress created. The magnitude of the load did not directly affect the displacement, while the load distribution had a direct effect on the displacement. With the centralization of the applied load, the maximum stress created moved further away from the crown. Moreover, temperature loading influenced the behaviour and resistance of the GFRP materials. Cyclical temperature changes made the material more brittle, and the range of elastic behaviour decreased. In addition, fluctuations in the structure under the wind flow with higher velocity were limited, and the models were exposed to the wind flow with more rigid performance. With raising the f⁄L ratio, a rotating area was formed in the windward side near the ground.
Finally, based on the findings, a new design was proposed to prove the developed knowledge in a full-scale model. Also, this design showed the intelligent side of bending active theory, which flat elements could achieve a 3D structural shape with the ability of reversing back to their original shape without any permanent deformations caused and external support required.
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