124,815 research outputs found
Advanced finite element modeling of textile-reinforced mortar strengthened masonry
No full textFabric-reinforced cementitious matrix (FRCM) strengthening is an innovative technology for effective reduction of seismic vulnerability of existing masonry and historical structures. At present, numerical modeling strategies for evaluation of the in- and out-of-plane performance of masonry structures strengthened with these composites are in their embryonic stage. The present chapter is aimed at presenting two alternative approaches to such strategies. In particular, a detailed 3D heterogeneous and an inexpensive homogenization approach are reviewed. In the first model, brick and mortar joints are meshed separately with 3D eight-noded elements, whereas FRCM is discretized using trusses (fiber grid) and 3D eight-noded elements (cementitious matrix). These 3D elements are made in all cases with a softening and damage behavior with plasticization, both in tension and compression, using the concrete damage plasticity model. In the homogenization approach, masonry is substituted with an equivalent nonlinear orthotropic material exhibiting softening. The elementary cell is discretized using a few triangular elastic elements (bricks) and holonomic interfaces (joints) in which all the nonlinearities are lumped. The FRCM reinforcement is applied to the homogenized masonry using equivalent trusses with limited tensile strength and fragile behavior, connecting adjoining rigid elements. Equivalent mechanical properties of the trusses can be eventually tuned accounting for FRCM debonding or rupture of the fibers. The pros and cons of the two numerical procedures are discussed with respect to their reliability in fitting experimental force-displacement curves and crack patterns, as well as to the rather different computational effort required by the two strategies
Pushover analysis of fiber-reinforced polymer-strengthened masonry
No full textThis chapter presents an overview of modeling techniques commonly used for pushover analysis fiber-reinforced polymer (FRP)-strengthened masonry components. This technique, consisting of a static nonlinear analysis generally performed by monotonically increasing lateral loads, is also referred to as static nonlinear analysis and is a common analysis method for evaluating the nonlinear performance of structural components or validation of experimental results. Nonlinear analysis of masonry structures is already a challenging task due to the complex and heterogeneous nature of these materials. Application of FRP composites to masonry structures introduces new complexities that should be adequately addressed for numerical simulation of these components at the structural level. A discussion on how these challenges are tackled in practice and in research are presented here with a focus on strengthened walls and arches
A fast modeling approach for numerical analysis of unreinforced and FRCM reinforced masonry walls under out-of-plane loading
No full textA new discretized homogenization approach is proposed in this study in order to predict the behavior of unreinforced and FRCM reinforced masonry structures. The proposed approach allows overcoming the common disadvantages of the existing homogenization approaches: (a) being difficult to implement and (b) not allowing to couple the in-plane and out-of-plane actions. Reference experimental results and detailed numerical modeling are used for validation of the proposed modeling strategy. In the proposed model, the elastic cells are linked by homogenized interfaces. The mechanical properties coming from the homogenization procedures are lumped at the interfaces by means of the generic Concrete Damage Plasticity model, allowing easy implementation and avoiding computational issues peculiar to other approaches available in the literature. The new approach shows accurate results in predicting the global behavior and the damage pattern for both unreinforced and FRCM strengthened masonry walls. The results are promising also with a view to be applied for more complex reinforced applications as double curvature masonry structures
Numerical Modeling of Masonry and Historical Structures: From Theory to Application
No full textNumerical Modeling of Masonry and Historical Structures: From Theory to Application provides detailed information on the theoretical background and practical guidelines for numerical modeling of unreinforced and reinforced (strengthened) masonry and historical structures. The book consists of four main sections, covering seismic vulnerability analysis of masonry and historical structures, numerical modeling of unreinforced masonry, numerical modeling of FRP-strengthened masonry, and numerical modeling of TRM-strengthened masonry. Each section reflects the theoretical background and current state-of-the art, providing practical guidelines for simulations and the use of input parameters
Numerical prediction of the mechanical behavior of TRM composites and TRM-strengthened masonry panels
No full textThe work concerns the detailed finite element modelling of multiscale experimental tests performed on glass-Textile Reinforced Mortars (TRM) with the aim of investigating the complex three-dimensional aspects associated with the TRM behavior and understanding what parameters are crucial for the correct simulation and prediction of the composite’s response at each scale. The investigation ranges from materials to structural scale. Each sample’s component and its interfaces are modeled individually. The results show that the 3D micro-modelling successfully replicates the experimental TRM response at different scales by using consistent materials parameters in all the simulation levels, proving a comprehensive understanding of the composite behavior and performance
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Non-linear homogenized and heterogeneous Fe models for FRCM reinforced masonry walls out-of-plane loaded
No full textTwo distinct non-linear FE modeling techniques are compared to have an insight into the efficacy of FRCM reinforcement for masonry subjected to out-of-plane loads. In particular, both a micro-modeling technique and a homogenization approach are compared. The first approach is a tridimensional heterogeneous procedure where constituent materials (bricks, joints, reinforcing mortar and reinforcing grid) are modeled separately. The second technique is a consolidated two-step homogenization where the meso-scale homogenization problem is solved discretizing the elementary cell with few elastic constant stress triangles (bricks) and non-linear interfaces (joints). The non-linear structural analyses are performed replacing masonry at the macro-scale with an assemblage of rigid elements interconnected by non-linear homogenized springs (HRBSM modelling). Both models are directly implemented in the commercial software Abaqus. Advantages and limitations of the two approaches are discussed in detail -especially as far as the rather different computational effort required by the two strategies is concerned-with reference to their ability in reproducing global force-displacement curves and crack patterns of some reinforced wallettes in simple bending
Application of homogenization approaches for modeling of FRCM-strengthened masonry
No full textThe creation of an effective, accurate finite element mesh is crucial for running whatsoever numerical analysis on structural models. This is especially true when micro-scale, mesoscale, and homogenization-based approaches are used, since they involve a precise and distinct representation of the constitutive materials. One fitting example is embodied by masonry with irregular bond, where blocks are randomly assembled and often present different shapes and dimensions. This work presents a Matlab script for the generation of a full 3D finite element mesh, which is created directly from a simple rasterized picture of the masonry element under investigation. A voxel approach is here used, where one pixel of the image is turned into one solid finite element. The resulting 3D mesh is employed into a broader Matlab script which derives homogenized failure surfaces for masonry test-windows. In particular, the effectiveness of the 3D mesh is validated by comparing the homogenized failure surfaces obtained for an in-plane loaded masonry panel to those retrieved from the 2D version of the script with a 2D mesh, whose reliability has already been established
Fast discrete homogenization approach for the analysis under out-of-plane loads of unenforced and TRM reinforced masonry panels
No full textA novel discretized homogenization strategy has been developed in order to deal with the analysis of masonry structures. In particular, unenforced and TRM reinforced masonry panels have been simulated under out-of-plane-loads The proposed method provides several advantages when compared with the already existing homogenization approaches. Bricks and mortar have been substituted by elastic cells linked by homogenized interfaces where the non-linear properties are lumped. Such interfaces are modeled as 8-noded 3D bricks along with a Concrete Damage Plasticity model, already available in Abaqus. In fact, the implementation at a structural level of the homogemzed properties results faster and easier. leading to major competitiveness and even ensuring the coupling of the in-plane and out-of-plane actions. The proposed strategy has been tested and validated by comparison with experimental references available in the literature and numerical references, provided by the authors, based on a micro-modeling approach. The results are highly satisfactory in the prediction of the damage pattern and of the global behavior of me analyzed masonry panels
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