1,721,051 research outputs found
Prediction of concrete compressive strength by combined non-destructive methods
No full textThe compressive strength of concrete fc is one of most important mechanical parameter in the performance assessment of existing reinforced concrete (RC) structures. Many non-destructive testing methods have been developed to estimate the in situ value of fc. In particular, the combination of rebound hammer and ultrasonic pulse velocity (UPV) tests, known as SonReb method, is frequently used. In this paper an experimental research has being carried out involving both destructive and non-destructive testing methods for the evaluation of structural performance of existing RC structures. The aim of this study is to verify the reliability of predicting fc by some formulas available in literature involving measured parameters such rebound index and UPV
An Overview of Seismic Risk Management for Italian Architectural Heritage
No full textThe frequent occurrence of seismic events in Italy poses a strategic problem that involves either the culture of preservation of historical heritage or the civil protection action aimed to reduce the risk to people and goods (buildings, bridges, dams, slopes, etc.). Most of the Italian architectural heritage is vulnerable to earthquakes, identifying the vulnerability as the inherent predisposition of the masonry building to suffer damage and collapse during an earthquake. In fact, the structural concept prevailing in these ancient masonry buildings is aimed at ensuring prevalent resistance to vertical gravity loads. Rarely do these ancient masonry structures offer relevant resistance to actions other than vertical ones and then they are intrinsically vulnerable to stresses induced by the earthquakes. One of the main technical activities carried out by the Civil Protection after an earthquake is to assess the damage in the buildings and to evaluate their own usability. Regarding historical buildings, ad-hoc synthetic forms, drafted in agreement between the Italian Civil Protection Department and the Ministry of Cultural Heritage and Activities and Tourism and based on visual inspection, are adopted by qualified technicians. In this paper, such activities are described and discussed along with the Italian Civil Protection System. However, given the complexity of the main technical activities to be performed after an earthquake there is a need for more accurate methods based on Structural Health Monitoring
On the evaluation of the flexibility parameters of cracked beams based on the strain energy density theory
No full textIn this paper an approach that is able to derive the flexibility parameters in beams with an edge crack based on the strain energy density theory is presented. The method takes into account that the crack in a beam does not propagate in a collinear manner, but due to the presence of the mixed mode, it changes its direction. This allows a description of the phenomenon of the propagation of the crack similar to the experimental evidence. Preliminary results are presented for different position and initial length of the crack
Parametric Regression Model and ANN (Artificial Neural Network) Approach in Predicting Concrete Compressive Strength by SonReb Method
No full textThe commonly used NDT methods to predict concrete compressive strength include the rebound hammer test and the Ultrasonic Pulse Velocity (UPV) test. The poor reliability of rebound hammer and ultrasonic pulse velocity due to different aspects could be partially contrasted by using both methods together, as proposed.in the SonReb method, developed by RILEM Technical Committees 7 NDT and TC-43 CND. There are three techniques that are commonly used to predict fc based on the SonReb measurements: computational modeling, artificial intelligence, and parametric multi-variable regression models. The aim of this study is to verify the accuracy of some reliable parametric multi-variable regression models and ANN approach comparing the estimated compressive strength based on NDT measured parameters with the effective compressive strength based on DT results on core drilled in adjacent locations. The comparisons show the best performance of ANN approach
Fracture analysis for orthotropic cracked plates
No full textThe present investigation is intended to study the elastostatic fracture response of an orthotropic cracked plate subjected at infinity to a biaxial uniform load. The effects of orthotropy and load biaxiality on the near crack tip elastic fields is pointed out. Considering the non-singular terms, the angle of incipient crack propagation and the fracture loci are obtained. For this purposes the Strain Energy Density Theory and the Maximum Circumferential Stress Theory are considered and extended to orthotropic materials. A numerical analysis is performed for a wide range of orthotropic material properties and applied loads
Nanotechnology for biomedical applications: Recent advances in neurosciences and bone tissue engineering
No full textThe aim of this article is to give an overview of some recent advances of nanotechnology in medicine and bone tissue engineering, exploring typical applications of these emerging technologies. Currently, limitations in bone regenerative strategies include insufficient mechanical strength of scaffolds. Thus, we review the major area of research in nanotechnology with potential implications in bone regeneration: nano-based scaffold construction and modification to enhance biocompatibility, mechanical stability, and cellular attachment/survival. POLYM. ENG. SCI., 57:644â650, 2017. © 2017 Society of Plastics Engineers
Some Recent Advances of Ultrasonic Diagnostic Methods Applied to Materials and Structures (Including Biological Ones)
No full textAbstractThis paper gives an overview of some recent advances of ultrasonic methods applied to materials and structures (including biological ones), exploring typical applications of these emerging inspection technologies to civil engineering and medicine. In confirmation of this trend, some results of an experimental research carried out involving both destructive and non-destructive testing methods for the evaluation of structural performance of existing reinforced concrete (RC) structures are discussed in terms of reliability. As a result, Ultrasonic testing can usefully supplement coring thus permitting less expensive and more representative evaluation of the concrete strength throughout the whole structure under examination
A ROOF FOR THE ROMAN COIEDII DOMUS IN SUASA (ITALY)
No full textThe main objective of this paper is to discuss the architectural project consisting in protecting
the archaeological remains of the Roman Domus in Suasa. As well as being a structural and
technical problem, the construction of a roof transforms the archaeological site since it
inevitably adds a new element to the landscape. Two projects of cultural importance are
illustrated and discussed
On the inclined crack problem in an orthotropic medium under biaxial loading
No full textThe problem of an inclined crack in an orthotropic medium under biaxial loading is analyzed.
A suitable coordinate transformation is introduced and two decoupled systems of the Cauchy-Riemann type are obtained in terms of complex potentials. The crack problem is solved by using the method of analytic continuation and closed form expressions of the near tip stress and displacement fields are derived.
The influence of load biaxiality on the stress intensity factors, as well as on the local stress components is studied and graphically represented. Moreover, the action of material orthotropy on various quantities describing the crack characteristic is pointed out
Recent research progress on scaffolds for bone repair and regeneration
No full textCurrently, the major areas of research in nanotechnology with potential implications in ostearticular regeneration are: nano-based scaffold construction and modification to enhance biocompatibility, mechanical stability, and cellular attachment/survival. Nanotechnologies can be used to form scaffolds and to deliver drugs and growth factors in the lesion site in order to enhance bone formation. The aim of this paper is to give an overview of some recent advances of osteoarticular tissue engineering allowed by the application of nanotechnologies
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