Gaetano Zingone

CFRP sheets bonded to natural stone: interfacial phenomena

The effectiveness of the reinforcing technique consisting of fiber reinforced polymer sheets bonded to the structural elements depends on a good connection at the joint. This has to be able to ensure the transfer length of the shear stress in order to avoid a premature failure due to debonding. In this paper, the bond phenomenon at the interface is examined with reference to the calcarenite stone and carbon fiber reinforced polymer (CFRP) sheets in order to evaluate the possibility of utilizing this technique on masonry structural members, consisting of calcarenite ashlars and mortar. An experimental investigation is carried out on nine specimens obtained by applying unidirectional CFRP sheets to calcarenite squared-stone by using epoxy resin layers. All specimens were submitted to tensile force until the failure of the bond joint took place. Results allow us to deduce the local bond stress versus slip relationship, which is an important step toward understanding bond behavior at the joint interface.

Strength and Ductility of Hollow Circular Steel Columns Filled with Fibre Reinforced Concrete

Publisher Summary This chapter investigates the behavior of hollow circular steel cross-sections filled with Fiber Reinforced Concrete (FRC), subjected to monotonic loads. The casting of different types of composite members—steel columns, steel columns filled with Normal Strength Concrete (NSC), and steel columns filled with Fiber Reinforced Concrete (FRC) was employed. The columns were tested in uniaxial compression utilizing a universal testing machine operating in displacement control. The maximum strength of composite members filled with FRC was 20% higher than that recorded for steel pipes filled with FRC. After the peak load was reached, failure was due to the crushing of concrete and due to local and global buckling of the steel pipes. The vertical loads of the composite members were obtained by considering of the steel pipes and concrete core to strength, without any reduction in the transverse cross-section of the concrete core, because of the effective confinement reached in concrete inside steel pipes. In the case of FRC, the buckling effects were reduced by the presence of fibers and failure was due to essentially plasticization of materials ensuring a good prevision of experimental results with the analytical model based on these concepts. In the case of steel pipes filled with plain concrete, the buckling effects reduced the bearing capacity of the columns in the softening branch.

Shear Resistant Mechanisms Of HighStrength Fibre Reinforced Concrete Beams

This paper presents results of an experimental investigation carried out on high strength fibre reinforced concrete beams in the presence of traditional steel reinforcement, subjected to monotonic and cyclic loads. The aim of the investigation was to point out the effectiveness of the fibres as shear reinforcement of the beams, and to show the possibility of changing the shear mode of failure, characterised by high brittleness and poor dissipative capacities, into a flexural mode of failure, which is certainly more suitable in structures designed in seismic areas.