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To evaluate the strength of a connection after exposure to fire, the microstructure/property relationships and influences of these effects on high temperature strength are needed to discuss structural elements exposed to a heat treatment and to determine its mechanical properties. This study focuses on understanding the structural behavior of the connection under post-fire conditions. The aim of the work is also to provide a moment-rotation curve, failure mechanism and microstructure for a connection whose component is exposed to heat treatment. This aim was achieved through five tests that were conducted on a full-scale beam-to-column connection using a T-component obtained from rolled I-profiles by cutting along the web plane. The moment-rotation curves and failure modes of the connection at ambient temperature were compared to the moment-rotation curves and failure modes of the connection whose elements were exposed to high-temperature conditions. The material properties of the specimen element exposed to the heat treatment were also investigated by comparing them to those of the original specimen. The test results show that there are differences between the mechanical properties and microstructures of the heated and original specimens. The differences in these specimens are reflected in the morphology of the fractures. The reason for the fractures is that microstructure-changes contribute to brittle behavior in members. The experimental tests indicated that, post-fire, steel connections can be subjected to large deformations at a lower strength and are more likely to fracture early. [ABSTRACT FROM AUTHOR]

Composite shells of revolution are widely used as pressure vessels, reservoirs and tanks, rocket, spacecraft parts and in different elements of the building. The aim of this study is to investigate the buckling and post-buckling behavior of the cylindrical shell made of mild steel filled with melted waste polymer, polypropylene, filled with the silicon and the steel adhesive. Furthermore, seven thin-walled cylindrical shell specimens with different composite cover subject to hydrostatic pressure were tested in the present work. The results of testing under different theories and codes are compared. Also, one specimen was without composite cover (perfect model), which used to check other specimens. This study shows that the initial buckling value of all other specimen tests was higher than the perfect specimen and double layer CFRP coiling have a significant effect on the initial buckling value. However, using material between two cylinders instead of CFRP wrapping increased initial buckling value compared to the perfect specimen. The use of melted PP was more effective than other materials (silicone, steel adhesive glue and waste polymer). • CFRP wrapping has a significant effect on the initial buckling. • The melted PP (polypropylene) is good composite layer for thin-walled shells. • Adhesive layer does not affect the composite buckling meaningfully. • The adsorbed energy level for CFRP is more stable than the PP layered composite's. [ABSTRACT FROM AUTHOR]