Search results for " Structures"
showing 10 items of 4162 documents
Investigation of thick sheet AHSS springback in combined bending under tension
2012
In this paper, we investigate the springback behavior of several advanced high-strength sheet steels (TRIP, Dual-Phase, ferrite-bainite) with thicknesses up to 4 mm. Samples were tested by means of the bending-under-tension (BUT) test. The BUT has been extensively applied, in the literature, to relatively thin (1 mm and thinner) sheet metals for automotive applications; the applicability of several guidelines from the literature was investigated in this work in the context of thick advanced high strength steel (AHSS) sheets and using a sample width of 12 mm. The monotonic decrease of springback as back force increased was confirmed for this category of sheet steels, and a general trend for …
Conceptual design of prestressed slab bridges through one-way flexural load balancing
2013
In this paper a study on prestressed concrete slab bridges is presented. A design philosophy based on the concept of load balancing through prestressing is proposed in order to minimize the effects of delayed deformations due to creep. Aspects related to the stress redistribution inside these bridges for time-dependent phenomena are analyzed and discussed, by applying the principles of aging linear visco-elasticity. Prestressing is seen as an equivalent external load which counterbalances the permanent loads applied to the bridge, nullifying the elastic deflections due to sustained loads, and thus avoiding the related delayed deformations. An optimization of the structural behavior through …
Design and optimization of bonded patch repairs of laminated composite structures
2015
International audience; The present study proposes a method for design optimization of external patched repairs. The tensile behavior of notched specimens with patched repair was studied using finite element analysis and compared with experimental results. It was found that high stress concentrations along the transverse edges of circular patches and/or at the longitudinal edges of the hole leads to early damage initiation in the parent plate. The damage initiation site and its propagation depend on the patch in-plane stiffness. The optimal patch design can be characterized by a strength ratio R*. The overall design of the patch repair can be considered using a dimensionless design paramete…
Lighting in educational environments: An example of a complete analysis of the effects of daylight and electric light on occupants
2013
Abstract Light induces not only visual responses but also non-visual effects, indeed it affects performance, mood, attention and influences the synchronization of the biological clock. Duration, timing, intensity and the spectral power distribution of the light that reaches the eyes can have influence on human circadian rhythm and consequently on health. Given the important impact of the non-visual responses on people wellbeing, developing a model that allows lighting designers to predict them is a fundamental goal. In this paper a case study is reported: a series of measurements were carried out in a University classroom in order to study daylight and electric light characteristics and als…
Fatigue life under non-Gaussian random loading from various models
2004
Fatigue test results on the 10HNAP steel under constant amplitude and random loading with non-Gaussian probability distribution function, zero mean value and wide-band frequency spectrum have been used to compare the life time estimation of the models proposed by Bannantine, Fatemi–Socie, Socie, Wang–Brown, Morel and Łagoda–Macha. Except the Morel proposal which accumulates damage step by step with a proper ethodology, all the other models use a cycle counting method. The rainflow algorithm is used to extract cycles from random histories of damage parameters in time domain. In the last model, where a strain energy density parameter is employed, additionally spectral method is evaluated for …
3D simulations and experiments of guided wave propagation in adhesively bonded multi-layered structures
2010
Understanding guided wave propagation in multi-layered plates and interaction with discontinuities can be difficult, as well as the interpretation of the ultrasonic signals. Propagation of guided waves can be studied analytically solving the equations of motion with the proper boundary conditions; nevertheless analytical models can be difficult to solve for complex multi-layered structures or having inner discontinuities. The problem can be efficiently studied using numerical techniques. Simulation of guided wave propagation in multi-layered structures, for ultrasonic waves in the MHz range, is solved here with the finite element analysis based on an explicit integration rule to solve the e…
A microplane model for plane-stress masonry structures
2003
Publisher Summary For a refined nonlinear finite element analysis of masonry structures, an accurate constitutive model that is able to reproduce the desired phenomenological material features is required. Constitutive models for quasi-brittle materials, as plain concrete, have been proposed in the chapter, which allow to reproduce the very complex response in the two- or three-dimensional state of stress. Usually, the constitutive relations proposed are based on some appropriate extensions of elastic-plastic continuum models and more recently on continuum damage models. It has been observed that for these tensorial-based constitutive relations to be effective often require a large number o…
Incremental dynamic based fragility assessment of reinforced concrete structures: Stationary vs. non-stationary artificial ground motions
2017
Abstract Artificial and natural records are commonly employed by researches and practitioners to perform refined seismic assessments of structures. The techniques for the generation of artificial records and their effectiveness in producing signals which are significantly representative of real earthquakes are still debated as well as results of the consequent seismic assessment to expect from their application. The paper presents an in-depth comparative study highlighting the effect of employing different typologies of artificial ground motion records on seismic assessment results, especially addressing seismic fragility curves. Three sets of 50 stationary, nonstationary evenly modulated a…
Steel based retrofitting interventions for existing masonry walls: a comparative numerical investigation
2021
Masonry buildings constitute a significant portion of the architectural heritage all over the world, also in regions affected by a high seismic hazard. Since this constructional material is character-ized by lack of tensile strength, as well as small deformation capacity, masonry structures could result hugely damaged if shaken by seismic forces. In order to avoid collapses and reduce struc-tural damage, innovative retrofitting interventions are necessary to improve the seismic behavior of masonry structures. In this context, steel-based techniques could be considered among the most suitable solutions. In fact, by using such a high-performant material, additional strength and ductility may …
The use of wood with an anti-seismic function in the architecture of palermo during the 18th century
2016
The study analyzes the interventions in the historical buildings after the earthquakes that struck Palermo in 1726 and 1751, with a particular attention to the anti-seismic reinforcements. The research, based primarily on archival documents, focuses on a series of interventions in the architectural heritage, in which the use of wood for structural elements, was able to guarantee for an “antiseismic” reconstruction. Although wood was not commonly used as other materials (iron, for instance) in the post-earthquake reconstruction process of Palermo it was certified its use as an anti-seismic system in the reinforcements of the damaged buildings. It is documented, for instance, the insertion of…