https://hal.archives-ouvertes.fr/hal-01461938/document

Extended finite element method for cohesive crack growth

Modeling of the evolution of distributed damage such as microcracking, void formation, and softening frictional slip necessitates strain-softening constitutive models. The nonlocal continuum concept has emerged as an effective means for regularizing the boundary value problems with strain softening, capturing the size effects and avoiding spurious localization that gives rise to pathological mesh sensitivity in numerical computations. A great variety of nonlocal models have appeared during the last two decades. This paper reviews the progress in the nonlocal models of integral type, and discusses their physical justifications, advantages, and numerical applications.

Nonlocal integral formulations of plasticity and damage: Survey of progress

The performance of an interface elastoplastic constitutive model for the analysis of unreinforced masonry structures is evaluated. Both masonry components are discretized aiming at a rational unit-joint model able to describe cracking, slip, and crushing of the material. The model is formulated in the spirit of softening plasticity for tension, shear and compression, with consistent treatment of the intersections defined by these modes. The numerical implementation is based on modern algorithmic concepts such as local and global Newton-Raphson methods, implicit integration of the rate equations and consistent tangent stiffness matrices. The parameters necessary to define the model are derived from microexperiments in units, joints, and small masonry samples. The model is used to analyze masonry shear-walls and is capable of predicting the experimental collapse load and behaviour accurately. Detailed comparisons between experimental and numerical results permit a clear understanding of the walls structural behavior, flow of internal forces and redistribution of stresses both in the pre- and post-peak regime.

Multisurface Interface Model for Analysis of Masonry Structures

Seismic Rehabilitation of Existing Buildings

A review of methods applicable to the study of masonry historical construction, encompassing both classical and advanced ones, is presented. Firstly, the paper offers a discussion on the main challenges posed by historical structures and the desirable conditions that approaches oriented to the modeling and analysis of this type of structures should accomplish. Secondly, the main available methods which are actually used for study masonry historical structures are referred to and discussed. The main available strategies, including limit analysis, simplified methods, FEM macro- or micro-modeling and discrete element methods (DEM) are considered with regard to their realism, computer efficiency, data availability and real applicability to large structures. A set of final considerations are offered on the real possibility of carrying out realistic analysis of complex historic masonry structures. In spite of the modern developments, the study of historical buildings is still facing significant difficulties linked to computational effort, possibility of input data acquisition and limited realism of methods.

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Structural Analysis of Masonry Historical Constructions. Classical and Advanced Approaches

The influence of masonry infill panels on the seismic performance of reinforced concrete (RC) frames that were designed in accordance with current code provisions are investigated. Two types of frames are considered. One was designed for wind loads and the other for strong eqrthquake forces. Twelve 1/2-scale, single-story, single-bay, frame specimens were tested. The parameters investigated included the strength of infill panels with respect to that of the bounding frame, the panel aspect ratio, the distribution of vertical loads, and the lateral-load history. The experimental results indicate that infill panels can significantly improve the performance of RC frames. However, specimens with strong frames and strong panels exhibited a better performance than those with weak frames and weak panels in terms of the load resistance and energy-dissipation capability. The lateral loads developed by the infilled frame specimens were always higher than that of the bare frame. This is even true for the least ductil...

Experimental Evaluation of Masonry-Infilled RC Frames

The failure of unreinforced masonry structures subjected to lateral loads is dominated, to a large extent, by the fracture of mortar joints as well as the cracking and crushing of masonry units. This can be simulated by means of a finite element approach in which the mortar joints are modeled with interface elements and the masonry units are modeled with smeared crack elements. To this end, a dilatant interface constitutive model capable of simulating the initiation and propagation of interface fracture under combined normal and shear stresses in both tension-shear and compression-shear regions, and capable of simulating the experimentally observed dilatancy was developed in this study. The performance of the interface model in representing the behavior of masonry mortar joints is evaluated with the available experimental results. Furthermore, the failure of unreinforced concrete masonry panels is analyzed with the aforementioned approach. It is concluded that the numerical model is capable of predicting the response of a masonry assemblage based on the response of its basic constituents.

Interface Model Applied to Fracture of Masonry Structures

Experimental and analytical studies have been carried out to investigate the performance of masonry-infilled RC frames under in-plane lateral loadings. In this paper, the experimental results are concisely summarized, and a constitutive model is presented for the modeling of masonry mortar joints and cementitious interfaces in general. A smeared-crack finite element model is used to model the behavior of concrete in the RC frames and masonry units. It is shown that the finite element models are able to simulate the failure mechanisms exhibited by infilled frames including the crushing and cracking of the concrete frames and masonry panels, and the sliding and separation of the mortar joints. The lateral strengths obtained with these models are in good agreement with those obtained from the tests.

FINITE ELEMENT MODELING OF MASONRy-INFILLED RC FRAMES

Numerical modeling of masonry-infilled RC frames subjected to seismic loads

Composite floor systems, consisting of reinforced concrete slabs and steel girders, are common in buildings and bridges. Partial restraints at the interface of the concrete slab and the steel girder have significant effects on the response of the composite beam. A few analytical models capable of accounting for these effects are available; however, none can be efficiently used for the nonlinear analysis of composite beams. In this paper, the basic governing equations are presented for a composite beam with deformable shear connectors under small displacements. Based on these equations, a new composite beam element is developed using the force method of analysis. The performance of this new element is compared with that of a previously developed displacement-based composite beam element. Both elements consist of two beam components connected through a deformable interface. A distributed spring model is used to account for the shear deformation at the interface. Two numerical examples on the nonlinear behavior of composite beams are solved using both displacement- and force-based elements. Comparison of the numerical results shows the superior performance of the newly developed force-based element over the displacement-based element.

P. Benson Shing

Papers

Experimental Evaluation of Masonry-Infilled RC Frames

Interface Model Applied to Fracture of Masonry Structures

FINITE ELEMENT MODELING OF MASONRy-INFILLED RC FRAMES

Numerical modeling of masonry-infilled RC frames subjected to seismic loads

Nonlinear Analysis of Composite Beams with Deformable Shear Connectors