0000000000235694
AUTHOR
Colajanni P.
Innovative connections for steel-concrete-trussed beams: a patented solution
The most recent design strategies welcome the adoption of innovative techniques for seismic energy input mitigation, aiming to achieve high dissipation capacity, prevent the structure from collapse and ensure the serviceability of the construction. Friction damper devices have been widely adopted in framed steel structures for decades, while their introduction in different structural types is still under investigation. This paper presents the outcomes of innovative research supported by the industry and conducted on beam-to-column connections of RC structures in which the beams are Hybrid Steel-Trussed Concrete Beams (HSTCBs) and the columns are classical RC pillars. An innovative solution,…
Experimental characterization of friction properties of materials for innovative beam-to-column dissipative connection for low-damage RC structures
Low-damage design of structures in seismic-prone areas is becoming an efficient strategy to obtain "earthquake-proof" buildings, i.e. buildings that, even in the case of severe seismic actions, experience a low or negligible amount of damage. Besides the safeguard of human lives, this design strategy aims also to limit the downtime of buildings, which represents a significant source of economic loss, and to ensure an immediate occupancy in the aftermath of an earthquake. In this context, focusing on moment-resisting frames (MRFs), several solutions have been developed for the beam-to-column connections (BCCs) of steel and precast/prestressed concrete structures, but very few for cast-in-sit…
Finite element modeling of the shear behavior of hybrid steel trussed concrete beams
The development and calibration of a three-dimensional (3D) nonlinear Finite Element (FE) model is presented with the aim of investigating the shear behavior of steel-concrete composite beams realized with a steel truss embedded into a concrete core and named Hybrid Steel Trussed-Concrete Beams (HSTCBs). The model is calibrated on the results of a reference experimental campaign of three-point bending tests on HSTCBs realized at the Laboratory of Structures of the University of Palermo. The actual behavior at the steel-concrete interface has been introduced in the model through the implementa-tion of a cohesive constitutive relationship. Furthermore, the damaged plasticity of concrete has b…
Comparative analysis of shear resisting models for hybrid steel trussed concrete beams
The hybrid steel trussed concrete beams represent a structural solution widely adopted in the industrial constructions thanks to the numerous advantages due to their use, such as economic convenience, high performances and constructional speed de-riving from the partial prefabrication process and from the self load-carrying capacity of the beam in the first operative phase, prior to the in-site casting of concrete. The hybrid steel trussed concrete beams examined in the present study are constituted by two prin-cipal components, i.e. a steel joist with inclined rebars, realized in industry, which is welded to a smooth steel plate and then embed-ded within the concrete material cast in situ.…
Friction-based beam-to-column connection for low-damage RC frames with hybrid trussed beams
Hybrid Steel-Trussed Concrete Beam (HSTCB) is structural typology suitable for light industrialization. HSTCBs usually cover long span with small depths, which lead to significant amount of longitudinal rebars. The latter make beam-column joints more prone to damage due to earthquake-induced cyclic actions. This phenomenon can be avoided using friction-based BCCs. Friction devices at Beam-to-Column Connections (BCCs) have become promising solutions to reduce the damage experienced by structural members during severe earthquakes. Few solutions have been developed for cast-in-place Reinforced Concrete (RC) and steel-concrete composite Moment Resisting Frames (MRFs), because of the difficulty …
R.C. columns strengthened by PBO-FRCM under axial force and bending moment
Fabric-Reinforced Cementitious Matrix (FRCM) systems, also known as Textile Reinforced Concrete (TRC) are nowadays widely used as confining material to enhance both strength and deformation capacity of columns of seismic resistant r.c. frames. In the past, when carbon fiber was used in the textile, experimental results showed that the efficiency of the wrapping is limited by the connection between substrate and fiber, which is not as effective as when epoxy resins are used. To improve the strength of the connection between fibres and mortar binder in FRCM system, the use of p-Phenylene BenzobisOxazole (PBO), having a molecular structure capable of establishing chemical bonds with hydrated c…
THE REHABILITATION THROUGH EXTERNAL PRESTRESSING OF HISTORICAL REINFORCED CONCRETE BRIDGES WITH REDUCED PERFORMANCE: A CASE STUDY
Many existing reinforced concrete bridges exhibit behaviour at the Service Limit State and the Ultimate Limit State which can be considered unsatisfactory with respect to the current provisions of Codes, but which are actually deficiencies deriving from obsolete calculation methods, structure age, material degradation, diffuse or localized corrosion and increased loads. Among these, cantilever bridges with half-joints may present a decrease in global safety coefficients for the most stressed current sections of the deck or in the local ones, that affect the performance of elements sensitive to degradation, such as Gerber saddles. In these cases, simple strengthening interventions through ex…
Influence of the effectiveness factors in assessing the shear capacity of RC beams strengthened with FRP
Shear failure of RC beams strengthened with composite textiles is often affected by the different failure modes characterizing the FRP reinforcement. The most relevant analytical models for evaluating the shear capacity of RC beams strengthened with FRP take into account these failure modes by introducing an effectiveness factor “R”, which reduces the ultimate FRP tensile stress. Moreover, the interaction between stirrups and FRP reinforcement leads to a reduced efficiency of the transverse steel reinforcement due to the brittle failure of composite textile which hinders the yielding of all the stirrups involved by critical crack. In this regard, some analytical models introduce an effectiv…
Response behaviour of reinforced concrete beams strengthened in shear with FRP
In this paper an analytical model, able to predict the shear-displacement response of slender RC beams reinforced in shear with FRP, is presented. It allows to evaluate the complete strain and stress fields, for each load step, on the basis of the MCFT framework. The key role of the effective strain of FRP reinforcement at failure has been investigated. At the same time, the interaction FRP-steel stirrups has been taken into account by introducing an appropriate factor. It is able to reproduce the decrease of stirrups stress level when an external reinforcement is used. The proposed model has been validate against a database of specimens collected in literature. Results have shown the remar…