Retrofit of Existing Reinforced Concrete (RC) Buildings: Steel vs. RC Exoskeletons

The existing building stock is largely made up of reinforced concrete (RC) buildings, constructed between the post-World War II period and 1981, and mostly consists of buildings constructed very quickly to meet the great housing demand of this period, and buildings that do not adhere to anti-seismic and energy regulations. Today, after more than fifty years, these buildings have reached the end of their useful life cycle and their maintenance is not sustainable, presenting a series of structural, energy and architectural problems and criticalities. The myriad of possible retrofit interventions currently available for these RC structures drastically reduces when the main requirement for interventions is to avoid operational interruptions to buildings. In this case, an additive structure, operating exclusively from the outside as an exoskeleton, is typically used for achieving appropriate retrofit. In this paper, two solutions are proposed and addressed for the retrofit of an existing RC building in Italy, one through the application of a steel exoskeleton and the other through the application of an RC exoskeleton system. A set of push-over (PO) analyses is carried out to define the performance point of both the original and combined systems. The comparative results of these solutions are then discussed

PREDICTION OF CYCLIC MOMENT-ROTATION BEHAVIOUR FOR TOP AND SEAT & WEB ANGLE CONNECTIONS BY MECHANICAL MODEL

ABSTRACT: In this paper, a simplified mechanical model of the joint with relative moment-rotation characteristics for use in analytical modelling of MRSF systems is presented. The experimental moment-rotation behaviour of fullscale connections is first considered followed by the development of a finite element model for them. The inelastic moment-rotation predictions of the finite element model are compared with available experimental data. Experimental results of full-scale connections are also compared with the mechanical model proposed by the Eurocode 3. Based on the results of this comparison, a simplified mechanical model of the connection is developed. This proposed simplified mechanical model still adopts the same "component method" approach of the Eurocode 3, but introduces a more refined criteria for the modelling of the unilateral contact between the cleat and the column flange, and a different expression for the evaluation of the joint capacity. An extensive parametric analysis is then conducted to assess the inelastic moment-rotation behaviour and the results are compared with finite element analyses and with available experimental data. The moment-rotation predictions of the simplified mechanical model are in good agreement with experimental tests and with finite element analyses. The simplified mechanical model also gives more consistent initial stiffness and nonlinear relative moment-rotation estimates if compared to the model proposed by the Eurocode 3. The results of the conducted analyses show that the simplified mechanical model gives results that are in reasonable agreement with experimental data and are more accurate than the results of the Eurocode 3-Annex J model

Multi-Span Steel–Concrete Bridges With Anti-seismic Devices: A Case Study

Seismic protection for structures in general, and bridges in particular, is very complex. Indeed, any analysis of bridges with fluid viscous dampers and shock transmitting devices must be completed using a sophisticated finite element (FE) model. Furthermore, a large number of factors must be accurately considered and followed in order to effectively and efficiently protect human life. When dealing with complex structures, as is the case of the viaduct under examination, which contains numerous devices, the starting point is an assessment of the consistency of fluid-viscous dampers and shock transmitters integrated with bearings. This paper, a case study of design and static-dynamic testing procedures on multi-span steel–concrete viaduct provided with fluid viscous dampers and shock transmitters devices, deals directly with this process. To these ends, the FE modeling of the viaduct required an updating procedure model to ensure optimization. Those viaducts built during the "Caltagirone Project," can be defined as works of great interest due both to the construction methods adopted and to the techniques of stress control during the seismic stage. The design process allowed a rectification of those seismic issues deriving from structural irregularities (altimetric and planimetric), as well as from the high seismicity of the area. The analyses were carried out using a Capacity Design approach, employing non-linear seismic dissipative devices integrated as supports while validating that the substructures are maintained substantially elastic. For this reason, the piers were modeled on their non-linear behavior using Takeda's hysteretic model. Moreover, fluid viscous dampers and shock transmitters integrated with bearings were designed in accordance with the substructures' different stiffness; this partially dissipates those stresses induced by earthquakes, in order to keep the deck and the substructures substantially elastic, establishing a Life-Safety Limit State condition (at the Ultimate Limit State—ULS). The verifications carried out demonstrated the capability of structures to withstand stresses under the Collapse Limit State (CLS) condition without damage and at the same time to ensure the curvature capability from the piers. The comparisons between experimental and numerical results together with the demanding qualification tests carried out by this study demonstrate that the hydraulic devices are an efficient solution to assess seismic stresses induced on the viaduct and in its substructures, confirming the reliability of the aforesaid devices, thus ensuring better structural safety

REALTÀ AUMENTATA E TECNICHE DI GEOMATICA PER LA VALORIZZAZIONE DEL PATRIMONIO SOTTOMARINO

The purpose of the research carried out by the Laboratory of Geomatics of the University of Reggio Calabria is to revive through applications of virtual reality natural scenarios and/or underwater artifacts within the framework of underwater heritage. Immersive Virtual can be use to spread information allowing to find information or phases of the design directly through the use of a mobile device. The subject of the research in question is the underwater reconstruction of some submerged glimpses of structures belonging to the former “Liquichimica” factory, located in Reggio Calabria. With the help of Revit and Agisoft Metashape, three-dimensional scenarios were obtained using photogrammetric techniques. A ROV (remote-controlled vehicles) was used for marine exploration adjacent to the area. The survey showed the causes that led to the collapse of these structures and the extent of the environmental impact on the marine ecosystem of the area, in terms of pollution and destruction of the submerged landscap