1,720,976 research outputs found
Simulation of monotonic, static and dynamic response of RC squat walls by means of PARC_CL 2.0 crack model
No full textIn this paper the PARC_CL 2.0 crack model, implemented in the ABAQUS Code user subroutine UMAT.for, is presented and applied to the non-linear finite element analyses (NLFEA) of reinforced concrete (RC) shear walls tested, by means of pseudo dynamic test (PSD), at the European Laboratory for Structural Assessment (ELSA, Joint Research Centre).
The PARC_CL 2.0 crack model is an evolution of the previous PARC versions and, with re-spect to them, it allows to take into account plastic and irreversible deformations. For this reason, it seems to be suitable for modelling the hysteretic cycles of both concrete and steel and to reproduce the cyclic response of structural R members. Moreover, within the PARC_CL 2.0 crack model, is implemented a formulation able to account for stiffness proportional damping in dynamic analyses.
The shear walls, tested by means of PSD test, at the ELSA laboratory have been used to vali-date the proposed PARC_CL 2.0 crack model; the shear walls have been modeled using multi-layered shell elements and NLFEA have been carried out considering several loading condition (static pushover, cyclic and dynamic). The static pushover analyses are used to evaluate the sensitivity of results to mesh discretization; several analyses have been carried out adopting different element size in order to see the effect on the structural response.Moreover, cyclic and dynamic analyses are used to evaluate the capability of PARC_CL 2.0 crack model to reproduce the hysteretic response of such RC structural members
NLFEA of reinforced concrete shear walls under cyclic loading by means of PARC_CL2.0 crack model
No full textA constitutive crack model, defined PARC_CL2.0 (Physical Approach for Reinforced Concrete under Cyclic Loading condition), for predicting the cyclic response of reinforced concrete (RC) structures is presented in this paper. The PARC_CL2.0 crack model, which is implemented in the user subroutine UMAT.for in Abaqus Code, is based on a smeared fixed crack approach and is applied to multi-layered shell and membrane elements modeling. The main purpose of such model is the realistic modeling of the hysteretic behavior of concrete and steel under reversed cyclic loading, obtained considering irrecoverable strains and nonlinear unloading curves whose represent the energy dissipation. The PARC_CL2.0 crack model is firstly validated using measured data from experimental tests on simple reinforced concrete panels subjected to reversed cyclic loading available in literature
Nonlinear static and dynamic finite element analyses of reinforced concrete shear walls using PARC_CL crack model
No full textIn this paper the PARC_CL1.1 model (implemented in the user subroutine UMAT.for in Abaqus Code) is presented and applied to the non-linear finite element analyses (NLFEA) of reinforced concrete (RC) shear walls tested, by means of pseudo dynamic test (PSD), at the European Laboratory for Structural Assessment (ELSA, Joint Research Centre) within the project SAFE [1]-[4]. These experimental tests are included as part of CASH benchmark, which is an international benchmarking program organised under an initiative of the OEDC-NEA (Nuclear Energy Agency). The main objective of CASH benchmark is to evaluate the reliability of predictive analysis tools and methods as well engineering practice know how to assess the seismic capacity of reinforced concrete shear walls to withstand strong earthquakes considered for beyond design situation.
The PARC_CL1.1 crack model is the extension of the previous PARC model [5]-[6], and allows to consider cyclic loads and plastic deformations in the unloading phase. The PARC_CL1.1 model is based on a fixed crack approach and smeared approach for the reinforcements.
The shear walls tested at the ELSA have been used to validate the proposed PARC_CL1.1 crack model; the shear walls have been modeled using multi-layered shell elements and NLFEA have been carried out considering several loading condition (static pushover, cyclic and dynamic)
Beyond design seismic assessment advanced methodologies for RC structures: PARC_CL for FEM analyses of nuclear power plants RC structures
No full textIn this paper it is presented the PARC_CL fixed crack model (implemented in the user subroutine UMAT.for in Abaqus Code), applied to the non-linear finite element analyses (NLFEA) of reinforced concrete (RC) structures used in nuclear power plants (NPP) under cyclic and dynamic loads. Applications of PARC_CL are presented in this paper: the cyclic analysis of a scaled model of a nuclear containment vessel and the dynamic simulation of a shaking table test of an electrical facility wall structure. The multi-layered shell elements modelling with PARC_CL demonstrated to adequately describe both global and local engineering demand parameters (EDP). Simulations results are provided in terms of displacements, strains and crack patterns. Although the simulations provided good results, some issues such as proper damping calibration in dynamic analysis, wall to foundation interface failure mode description and computational costs are open. Future developments of this research aim also to implement the new PARC_CL2.0 model with plastic strains and to extend it to other FEM codes
SIMULATION OF RC WALLS SEISMIC BEHAVIOUR WITH SHELL ELEMENTS AND PARC_CL MODELLING
No full textThe structural response of reinforced concrete (RC) wall system is usually characterized by low displacement values at the damage and ultimate limit states; such systems are then quite common in industrial and power plant buildings.
The paper presents for some case studies a brief review of experimental tests available in literature and non linear finite elements (NLFE) methods for pushover analysis. In particular, in the paper a multi-layered shell model based on the fixed crack approach PARC_CL (Physical Approach for Reinforced Concrete under Cyclic Loading condition) is presented. Advantages and critical aspects related to shell modelling of wall systems are highlighted by multi-level assessment; in particular by comparing NLFEA results, obtained with the proposed shell element modelling, with experimental observations, NLFEA results obtained with beam element modelling and analytical formulations prescribed by Eurocode 8 (EC8). In the paper it is demonstrated that multi-layered shell modelling can be a numerical tool for the analysis of different structural wall typologies, like ductile wall systems (coupled or uncoupled), dual systems (frame or wall equivalent) and squat or large wall system
Studio sperimentale sul taglio biassiale in travi a sezione quadrata.
No full textIn the scientific literature, there are limited studies about the effect of biaxial shear in reinforced concrete elements. However, this load condition is quite common in columns subjected to horizontal forces.
Moreover, the design and evaluation methods reported in the codes do not consider any interaction between the shear strength in the two principal directions of inertia.
The variable strut inclination truss analogy, useful in case of uniaxial load condition, must therefore be reconsidered in presence of biaxial shear.
This paper presents the results of an experimental campaign on full size beam, with square section, subjected to inclined shear: 6 beams have been tested in order to understand how the shear resistant domain is influenced by the direction of load application. Out of the 6 specimens, each with a size of 300x300 mm, two have been tested under uniaxial shear, two with a load inclined 45° and two with an inclination of 22.5° to the horizontal. Each pair of beams presents a specimen without transverse reinforcement and one containing a low amount of stirrups, representative of the reinforcing condition of several existing columns, made before the introduction of the seismic design in the codes.
All beams present a total length of 3 m and the same ratio of longitudinal reinforcement.
Appropriate preliminary studies have been carried out in order to properly design the experimental tests. Moreover, particular attention has been given to the test set-up, which required suitable supports and load points for the application of the inclined load.
Finally, an analytical model, modified according to Model Code and Eurocode 2 prescriptions, is presented
Shell modelling of a 1/13 scaled RC containment vessel under cyclic actions with PARC_CL crack model.
No full textThe energetic resources exploitation became a big issue in present days. Globally 30 countries in the world are also exploiting Nuclear Power Plants (NPPs) for the generation of energy. In this case energy production issue is correlated to the requirements for population safeguard against radiation leakage and to safe nuclear waste storing. However, many of these NPPs, which are still producing a large amount of energy, need or will need in short times a renewal process. Reinforced concrete members are of strong importance for the safety and for the proper operation of NPPs. One of the most important structural elements is then the reinforced concrete containment vessel, RCCV, of the reactor. The correct prediction of the RCCV behavior under sever action is essential for the assessment of existing structure safety and for the design of new ones. In the paper it is described the modeling of a 1/13 scaled reinforce concrete containment vessel tested at the National Center for Research on Earthquake Engineering of Taipei, Taiwan, under cyclic loading. The RCCV was analyzed by means of non linear finite elements analysis using multi layered shell elements. A secant total strain fixed crack model called PARC_CL, implemented at the University of Parma in the user subroutine UMAT.for in ABAQUS code, has been used to evaluate the mechanical non-linearity of RC elements. The multi layered shell elements approach with PARC_CL crack model provided good results in terms of local and global EDPs and it was able to give a good estimation of the post cracking behavior until failure. Simulations results are provided in terms of displacements, strains and crack patterns. Although analyses provided good results, some issues like the modeling of the structure to foundation interface are still open
On the non linear behaviour of joint connections between precast members realized using steel dowel
No full textValidation of NLFEA to simulate the instability of thin RC walls subjected to bidirectional loading
No full textNonlinear Finite Element Analysis (NLFEA) of the inelastic behaviour of RC walls are often carried out for uni-directional (in-plane) horizontal cyclic loading. In this paper the behaviour of RC walls with different cross-sections (T-shaped and U-shaped) subjected to bi-directional (in-plane and out-of-plane) loading is simulated by means of NLFEA. They are carried out with the software DIANA, using curved shell elements and a total strain crack model for concrete and embedded truss elements adopting Monti-Nuti model for the reinforcement. The aim of this paper is to validate this type of analysis by comparing the obtained results with experimental outcomes of two different RC slender walls, a T-shaped wall and a U-shaped wall, tested under quasi-static bidirectional cyclic load. In particular, the focus is on the comparison between different crack models (Fixed and Rotating crack models) and on the calibration of the Monti-Nuti model parameters for steel. NLFEA is found to acceptably simulate both the in-plane and out-of-plane behaviour observed during the experimental tests. The present work is the starting point for future research in which parametric studies on the influence of reinforcement content and detailing will be performed, assessing their influence on the bidirectional response of RC walls and namely on other less known deformation modes such as out-of-plane instability
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