A nonlinear procedure for the analysis of RC beams

Abstract This work deals with the development of a computational method for the nonlinear analysis of reinforced concrete beams subjected to general loading and constraint conditions, able to catch crack formation and propagation. To this aim, a layered beam finite element is developed. The displacement field along beam axis and height is modelled through polynomial functions, whose number of terms is varied based on the complexity of the considered problem. The mechanical nonlinearity of the material is taken into account by implementing a smeared constitutive model for cracked reinforced concrete elements. The effectiveness of the proposed procedure, which can be applied to the analysis of both new and existing buildings, is proved through comparison with significant experimental data from technical literature, relative to both statically determinate and indeterminate beams

Transverse reinforcement optimization of a precast special roof element through an experimental and numerical procedure

The transverse behavior of a long span three-plate precast roof element is investigated by means of an experimental and numerical research. The performed study highlights that the failure mode of this folded-plate element is strongly influenced by the amount of transverse reinforcement in the wings. This latter is usually designed through simplified methods, which often lead to over-dimensioning in terms of steel welded mesh. To avoid excessive costs for the producers, transverse reinforcement optimization should be required. In this work, a non-linear FE modelling was applied for this purpose. The reliability of the followed numerical procedure was first verified by an initial type testing (i.e. experimental load test up to failure). The agreement between numerical and experimental results showed the efficiency of the model in simulating all the main sources of non-linearity related to both material behavior and element geometry. Numerical analyses were so used to perform a parametric study as a function of transverse reinforcement amount, aimed at determining a coefficient of “model inaccuracy”. This coefficient should be used as a correction factor for the element design in routine calculations based on beam theory

Vulnerability assessment of Italian Rationalist architecture: two case studies

The work is focused on the structural vulnerability assessment of two historical constructions, chosen as case-studies representative of a recurrent typology of Italian rationalist architecture, dating back to the Fascist period, often hosting public offices. Both examined buildings have similar dimensions and geometry, being characterised by five/six storeys and by an almost square plan with an inner courtyard, and are located in EmiliaRomagna, in zones of medium seismic hazard. The older building, dating back to the Thirties and located in Ravenna, has a mixed masonry-reinforced concrete structure, while the other one, built in the late forties and located in Parma, is characterised by an unreinforced masonry structure with some limited reinforced concrete elements. For the vulnerability assessment of the two buildings, a multi-disciplinary approach was followed, including the historical documents search concerning both the investigated buildings and the surrounding areas, the detailed geometrical and structural survey, the identification of materials, and in situ and laboratory tests to evaluate materials mechanical properties. These activities allowed reaching an adequate level of knowledge about the present conditions of the structures and their critical deficiencies. This knowledge path is not only necessary for the subsequent numerical analyses, but is also important as it allows targeting the repairing interventions, possibly reducing their final costs, in agreement with the “minimum intervention” approach for heritage buildings

Experimental investigation on the mechanical behaviour of AAC blocks for sustainable concrete masonry.

To satisfy the increasing demand of energy efficient buildings, AAC manufacturers are nowadays encouraged to produce blocks with ever lower densities. However, a compromise between energy-saving requirements and mechanical performances is needed to ensure structural safety, as well as an adequate structural durability. This paper reports a comprehensive experimental study on AAC mechanical properties (compressive and tensile strengths, as well as fracture energy), and on their dependency from material density and moisture content. The collected data are compared with some well-known analytical relations taken from the literature, which are often used for the calibration of mechanical parameters required for mathematical and/or finite element modelling of AAC load-bearing masonry, as well as of AAC masonry-infilled framed structures. These comparisons highlight some critical issues in the formulation of analytical relations having a general applicability; however, it was found that RILEM suggestions are appropriate for the considered AAC productions, at least for densities greater than 400 kg/m3

Experimental investigation on the mechanical behaviour of AAC blocks for sustainable concrete masonry

To satisfy the increasing demand of energy efficient buildings, AAC manufacturers are nowadays encouraged to produce blocks with ever lower densities. However, a compromise between energy-saving requirements and mechanical performances is needed to ensure structural safety, as well as an adequate structural durability. This paper reports a comprehensive experimental study on AAC mechanical properties (compressive and tensile strengths, as well as fracture energy), and on their dependency from material density and moisture content. The collected data are compared with some well-known analytical relations taken from the literature, which are often used for the calibration of mechanical parameters required for mathematical and/or finite element modelling of AAC load-bearing masonry, as well as of AAC masonry-infilled framed structures. These comparisons highlight some critical issues in the formulation of analytical relations having a general applicability; however, it was found that RILEM suggestions are appropriate for the considered AAC productions, at least for densities greater than 400 kg/m3

Scaling to technological readiness levels 6 in the bio-environmental laboratory

In this work, we present the Bio- Environmental Engineering scaling laboratory; that is located in Los Reyunos, Regional Development Technology Center. Its objective is the scaling of concept proof to pilot or prototype test for technology transfer suitable in real environments. We suggest the laboratory as an automatized Technological Demonstrator that allow us to adapt the work conditions making possible that the technology scope the degree of innovation with TRL 6. That scale test allows to know the parameters to apply in the territory mainly about ph, Eh, inlet flow, bioremediation system, kind irrigation, relationship between cycles.Fil: Scotti, Adalgisa. Comisión Nacional de Energía Atómica; ArgentinaFil: Cerioni, Juan Jesús. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Reviglio, Hugo. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Silvani, Vanesa Analia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Godeas, Alicia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Saavedra, Verónica Ana Isabel. Universidad Nacional de San Luis; ArgentinaFil: Visciglia, Mauricio. Gt Ingeniería Ambiental S.a.; ArgentinaFil: Cerioni, Sol. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Biondi, Roberto. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Turano, Juliana. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Quiroga, Camila. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Genovese, Felipe. Universidad Tecnologica Nacional. Facultad Regional San Rafael; ArgentinaFil: Gomez, Martin. Comisión Nacional de Energía Atómica; Argentin

Experimental characterization of fiber-reinforced cementitious mortar under tension

This work focuses on the mechanical characterization of the inorganic matrix used for Fiber-Reinforced Cementitious Matrix (FRCM) composites, nowadays widely used to retrofit existing reinforced concrete and masonry structures. While several works in technical literature investigate the experimental behavior of the whole FRCM composite, few information are available on the mechanical characterization of the mortar, which contains polymers and synthetic fibers in its admixture. However, the knowledge of its behavior in tension, especially after crack formation, is an important feature for the calibration of constitutive models to be adopted in the study of structural elements strengthened with FRCM. To this aim, an experimental program was performed on mortar specimens characterized by different shapes and dimensions, tested under direct tension or three-point-bending. From the performed tests, it was possible to characterize inorganic matrix behavior both in the uncracked stage, through the determination of the elastic parameters (elastic modulus and Poisson’s coefficient), and in the cracked stage. The use of digital image correlation (DIC) technique also allowed the study of the evolution of crack propagation in the specimens. Lastly, a correlation factor between axial and flexural tensile strength is proposed, for both design and numerical modelling purposes

Numerical modeling of the behaviour of SFRC elements in presence of multiple cracks

In this work, 2D-PARC constitutive relation has been extended to the analysis of SFRC elements subjected to plane stresses. The proposed model is based on a strain decomposition procedure, which easily allows to take into account multiple cracking stages. The total strain is so obtained by superposing the strain of concrete between two adjacent cracks to those of the cracks, while the stress is the same in all the “materials”. The mechanical behaviour of steel fibre reinforced concrete, in which the only resistant mechanisms across crack are due to aggregate and fibre contributions, has been adequately accounted in the cracked stiffness matrix. This model has been implemented into a FE code and validated by simulating some experimental tests carried out on SFRC slabs, representing a portion of industrial pavements included between joints, in which the failure is dominated by the presence of multiple cracks. These comparisons have highlighted that the proposed nonlinear approach is able to correctly represent slab behaviour until failure