scholarly journals Numerical and Experimental Analysis of Full Scale Arches Reinforced with GFRP Materials

2014 ◽  
Vol 624 ◽  
pp. 502-509 ◽  
Author(s):  
Ismael Basilio ◽  
Roberto Fedele ◽  
Paulo B. Lourenço ◽  
Gabriele Milani
Keyword(s):  
Upper Bound ◽  
Limit Analysis ◽  
Experimental Analysis ◽  
Failure Mechanisms ◽  
Peak Load ◽  
Numerical Results ◽  
Masonry Arches ◽  
Reinforced Masonry ◽  
The University

In this contribution, original limit analysis numerical results are presented dealing with some reinforced masonry arches tested at the University of Minho-UMinho, PT. Twelve in-scale circular masonry arches were considered, reinforced in various ways at the intrados or at the extrados. GFRP reinforcements were applied either on undamaged or on previously damaged elements, in order to assess the role of external reinforcements even in repairing interventions. The experimental results were critically discussed at the light of limit analysis predictions, based on a 3D FE heterogeneous upper bound approach. Satisfactory agreement was found between experimental evidences and the numerical results, in terms of failure mechanisms and peak load.

Dynamic Response of FRCM Reinforced Masonry Arches

2019 ◽  
Vol 817 ◽  
pp. 285-292 ◽  
Author(s):  
Anna Castellano ◽  
Aguinaldo Fraddosio ◽  
Jacopo Scacco ◽  
Gabriele Milani ◽  
Mario Daniele Piccioni
Keyword(s):  
Dynamic Response ◽  
Dynamic Behavior ◽  
Test Bench ◽  
Structural Elements ◽  
Dynamic Tests ◽  
Base Shear ◽  
Masonry Arches ◽  
Dynamic Excitation ◽  
Reinforced Masonry

The problem of the dynamic behavior of masonry arches and vaults has gained increasing interest in recent years, since the key role of these structural elements in the masonry constructions, especially of historic interest. Despite this, the literature still lacks a sufficiently large number of contributions on this important subject, and this deficiency is even more marked for the case of reinforced masonry. In this context, the present paper shows and discusses some preliminary experimental results on full-scale dynamic tests on unreinforced and GFRCM-reinforced Apulian tuff masonry arches. The experiments have been performed by using a test bench appositely designed and built; the dynamic excitation consisted of a harmonic base motion with fixed amplitude and increasing frequency. The acceleration in suitable points of the arches, the base shear and the base motion have been continuously monitored during the tests.

scholarly journals Static and seismic passive earth pressure coefficients on rigid retaining structures

2000 ◽  
Vol 37 (2) ◽  
pp. 463-478 ◽  
Author(s):  
A -H Soubra
Keyword(s):  
Failure Mechanism ◽  
Upper Bound ◽  
Limit Analysis ◽  
Earth Pressure ◽  
Numerical Results ◽  
Passive Earth Pressure ◽  
Pressure Coefficients ◽  
Passive Pressure ◽  
Analysis Theory ◽  
Earthquake Effects

The passive earth pressure problem is investigated by means of the kinematical method of the limit analysis theory. A translational kinematically admissible failure mechanism composed of a sequence of rigid triangles is proposed. This mechanism allows the calculation of the passive earth pressure coefficients in both the static and seismic cases. Quasi-static representation of earthquake effects using the seismic coefficient concept is adopted. Rigorous upper-bound solutions are obtained in the framework of the limit analysis theory. The numerical results of the static and seismic passive earth pressure coefficients are presented and compared with the results of other authors.Key words: limit analysis, passive pressure, earthquake.

Fast and Reliable Limit Analysis Approach for the Structural Assessment of FRP-Reinforced Masonry Arches

2017 ◽  
Vol 747 ◽  
pp. 196-203 ◽  
Author(s):  
Andrea Chiozzi ◽  
Gabriele Milani ◽  
Nicola Grillanda ◽  
Antonio Tralli
Keyword(s):  
Limit Analysis ◽  
Experimental Tests ◽  
Exact Representation ◽  
Arbitrary Geometry ◽  
Load Bearing Capacity ◽  
Masonry Arches ◽  
Reinforced Masonry ◽  
Initial Mesh ◽  
Masonry Material ◽  
Frp Reinforcement

This contribution is devoted to assess the capability of a new upper-bound approach for the limit analysis of FRP-reinforced masonry arches by comparing it to both experimental tests and a number of existing numerical procedures. The approach is based on an idea previously presented by the Authors and relies on the representation of the geometry of both the arch and of FRP reinforcement through Non Uniform Rational B-Spline (NURBS) functions. This allows generating a rigid body assembly starting from the assigned geometry composed by very few elements which still provide an exact representation of the original shape. A homogenized kinematic formulation for the limit analysis of the obtained rigid blocks assembly is derived, which accounts for the main properties of masonry material. FRP material is included exploiting the Italian CNR Recommendations for the design of FRP based reinforcing interventions. The approach is capable of accurately predicting the load bearing capacity of masonry arches of arbitrary geometry, provided that the initial mesh is adjusted by means of a suitably devised Genetic Algorithm (GA) until the active interfaces among blocks (e.g. hinges) closely approximate the actual failure mechanism.

scholarly journals Computational Methods for Masonry Vaults: A Review of Recent Results

2014 ◽  
Vol 8 (1) ◽  
pp. 272-287 ◽  
Author(s):  
A. Tralli ◽  
C. Alessandri ◽  
G. Milani
Keyword(s):  
Tensile Strength ◽  
Upper Bound ◽  
Limit Analysis ◽  
Failure Mechanisms ◽  
Point Of View ◽  
Large Set ◽  
Masonry Structures ◽  
No Tension Material ◽  
Masonry Vaults ◽  
Analytical Approaches

The present paper makes a critical review of some methods and models, now available in the technical litera-ture and commonly used in the analysis of masonry vaults up to their collapse, by highlighting advantages and drawbacks of each approach. All methods adopted to describe the mechanical behavior of masonry structures, in order to be reliable, must take into account the distinctive aspects of masonry, namely the scarce (or zero) tensile strength, the good resistance in compression and the occurrence of failure mechanisms through rotation-translation of rigid macro-blocks. Classic no-tension material models disregard the small existing tensile strength and make the assumption of (1) infinitely elastic be-havior in compression and (2) isotropy, giving thus the possibility to deal with either semi-analytical approaches (espe-cially for arches) or robust numerical procedures. More advanced but rather complex models are nowadays able to deal al-so with anisotropy induced by texture, small tensile strength and softening in tension, as well as by finite strength in com-pression. Traditionally – and nowadays it is still an opinion commonly accepted, in contrast with step by step complex procedures, Limit Analysis has proved to be the most effective Method for a fast and reliable evaluation of the load bear-ing capacity of vaulted masonry structures: classic lower and upper bound theorems recall respectively the concepts of equilibrium and occurrence of failure mechanisms with rigid elements. The so-called Thrust Network Method moves its steps from lower bound theorems, whereas FE limit analysis approaches with infinitely resistant elements and dissipation on interfaces take inspiration from the upper bound point of view. An alternative to Limit Analysis is represented by tradi-tional FEM combined with either elastic-plastic or damaging models with softening, commonly used for other materials but recently adapted also to masonry. They are able to provide a large set of output numerical information but further studies are still needed to ensure their proper application.

NURBS-Based Upper Bound Limit Analysis of FRP Reinforced Masonry Vaults through an Efficient Mesh Adaptation Scheme

2019 ◽  
Vol 817 ◽  
pp. 205-212
Author(s):  
Nicola Grillanda ◽  
Andrea Chiozzi ◽  
Gabriele Milani ◽  
Antonio Tralli
Keyword(s):  
Upper Bound ◽  
Limit Analysis ◽  
Mesh Adaptation ◽  
Accurate Estimation ◽  
Collapse Mechanism ◽  
Masonry Construction ◽  
Reinforced Masonry ◽  
Nurbs Surfaces ◽  
Masonry Vaults ◽  
Adaptation Scheme

Masonry vaults represent one of the typical structural typologies in historical masonry buildings. The study of the ultimate behavior of masonry vaults, together with the need to design adequate retrofitting techniques, is of high relevance in the optics of the preservation of the cultural heritage. In this paper, a new approach for the limit analysis of masonry construction is applied to FRP reinforced masonry vaults. This approach relies on the representation of geometry through NURBS surfaces, upper bound formulation of limit analysis, idealization of the structure as an assembly of rigid bodies with dissipation allowed only along interfaces, and optimization by means of a mesh adaptation scheme. The presence of FRP strips can be taken into account in easy way, because they can be included simply by adding NURBS surfaces and assigning them an adequate delamination stress value. The efficient mesh adaptation is performed by means of a Prey Predator Algorithm, which has been proven to be very suited for these problems. The strength of the proposed method lies in an accurate estimation of load-bearing capacity and collapse mechanism obtained with a model which requires a very low computational effort.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

MATERIAL HANDLING MACHINES AND SYSTEMS – UMI-TWINN PROJECT CONTRIBUTION

2019 ◽  
Vol 12 (1) ◽  
pp. 7-20
Author(s):  
Péter Telek ◽  
Béla Illés ◽  
Christian Landschützer ◽  
Fabian Schenk ◽  
Flavien Massi
Keyword(s):  
Material Handling ◽  
Digital Data ◽  
Flow Process ◽  
Research Directions ◽  
Scientific Excellence ◽  
Research Activities ◽  
New Research ◽  
Eu Project ◽  
The University

Nowadays, the Industry 4.0 concept affects every area of the industrial, economic, social and personal sectors. The most significant changings are the automation and the digitalization. This is also true for the material handling processes, where the handling systems use more and more automated machines; planning, operation and optimization of different logistic processes are based on many digital data collected from the material flow process. However, new methods and devices require new solutions which define new research directions. In this paper we describe the state of the art of the material handling researches and draw the role of the UMi-TWINN partner institutes in these fields. As a result of this H2020 EU project, scientific excellence of the University of Miskolc can be increased and new research activities will be started.

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