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• Iron-based Shape Memory Alloy rebars are available in the construction sector. • They can generate recovery stresses easily due to the shape memory effect. • Hollow Core Slabs structural floors improve their behaviour with continuity. • An active continuity of these structural floors can be achieved with Fe-SMA. • The experimental results ensure an improvement in Service Limit State. Despite the relatively recent introduction of Iron-based Shape-Memory Alloys (Fe-SMA) into structural engineering, more than 150 real applications have been performed to date in Central Europe, especially in retrofitting projects. Thanks to the Shape-Memory Effect, a prestrained and correctly anchored Fe-SMA bar can generate recovery stresses when heated up to 160 °C (activation) or more, and then cooled down. This paper presents research results about using Fe-SMA reinforcing bars as active (prestressed) continuity reinforcement in the hogging bending moment region of Hollow Core Slabs structural floors (HCS-sf). An experimental campaign was designed and carried out on eight HCS-sf specimens, four with concrete topping and four without, and two different slab heights. Using the HCS-sf specimens with the activated Fe-SMA bars resulted in better behaviour in the Service Limit State, which preliminarily proved the effectiveness of the proposed methodology for the specimens with concrete topping, although construction problems arose with the specimens without concrete topping. [ABSTRACT FROM AUTHOR]

• Seven full-scale RC beam-column joints strengthened externally by steel caging. • Specimens reinforcement designed with non-ductile details. • Experimental test with gravity and horizontal cyclic loads. • The strengthening improve the bond between reinforcement and concrete inside the joint. • Angles contributed notably to the bending moment capacity of the specimen. Beam-column joints suffer intense damage from seismic events and are the cause of many buildings collapsing. These zones present complex behaviour under cyclic loads, including tensile-compression cycles, which make reinforcement adherence worse and cause severe cracking in concrete. Although columns can be strengthened by various methods (e.g. concrete jacketing, fibre-reinforced polymers and steel jacketing-caging), beam column joints require complex systems being applied, but are not always effective. In Europe, fitting steel caging around columns is one of the most frequently used techniques, although its effectiveness against seismic events requires further study. The aim of this work is to analyse the behaviour of beam-column joints strengthened by steel caging subjected to cyclic loading, for which an ambitious experimental campaign was carried out on seven full-scale steel-caged specimens with a variety of strengthening solutions at joints. The results provide insight into the complex behaviour of joints with columns strengthened in this way, used as the basis for practical recommendations for engineers and architects who have to routinely retrofit structures against seismic events. [ABSTRACT FROM AUTHOR]

The present paper investigates structural response and buckling of long unstiffened thin-walled cylindrical steel shells, subjected to bending moments, with particular emphasis on stability design. The cylinder response is characterized by cross-sectional ovalization, followed by buckling (bifurcation instability), which occurs on the compression side of the cylinder wall. Using a nonlinear finite element technique, the bifurcation moment is calculated, the post-buckling response is determined, and the imperfection sensitivity with respect to the governing buckling mode is examined. The results show that the buckling moment capacity is affected by cross-sectional ovalization. It is also shown that buckling of bent elastic long cylinders can be described quite accurately through a simple analytical model that considers the ovalized prebuckling configuration and results in very useful closed-form expressions. Using this analytical solution, the incorporation of the ovalization effects in the design of thin-walled cylinders under bending is thoroughly examined and discussed, considering the framework of the provisions of the new European Standard EN1993-1-6. [ABSTRACT FROM AUTHOR]