Search results for "Shear strength"
showing 10 items of 75 documents
Temporal control of xyloglucan self-assembly into layered structures by radiation-induced degradation
2016
Partially degalactosylated xyloglucan from tamarind seeds (Deg-XG) is a very appealing biopolymer for the production of in situ gelling systems at physiological temperature. In this work, we observe that the morphology of hydrogels evolves towards high degrees of structural organization with time, yielding to dense stacks of thin membranes within 24 h of incubation at 37 °C. We also explore the possibility offered by gamma irradiation of controlling the time scale of this phenomenon, the final morphology and mechanical properties of the system. Structural and molecular modifications of Deg-XG with dose are investigated by FTIR, dynamic light scattering (DLS) and rotational viscosimetry. The…
Computational flow dynamics in a geometric model of intussusceptive angiogenesis.
2009
Intussusceptive angiogenesis is a process that forms new blood vessels by the intraluminal division of a single blood vessel into two lumens. Referred to as nonsprouting or intussusceptive angiogenesis, this angiogenic process has been described in morphogenesis and chronic inflammation. Mechanical forces are relevant to the structural changes associated with intussusceptive angiogenesis because of the growing evidence that physiologic forces influence gene transcription. To provide a detailed analysis of the spatial distribution of physiologic shear stresses, we developed a 3D finite element model of the intraluminal intussusceptive pillar. Based on geometries observed in adult intussuscep…
Retrofit of External Beam-Column Concrete Joints with Diagonally Crossed Reinforcement: Experimental and Analytical Investigations
2022
AbstractExperimental research was carried out regarding the flexural behavior under cyclic reversal loading of six full-scale external beam-column concrete joints cast with plain concrete in the pr...
Flexural behaviour of glulam timber beams reinforced with FRP cords
2015
Abstract Glued laminated timber (glulam) is widely used as a construction material to make up lightweight and large span structures. The basic principle of this material consists in bonding together a number of layers of dimensioned timber with structural adhesives, in order to increase strength and stiffness of the member, and allowing to make up sustainable structures with great visual impact. Recent applications showed the effectiveness of fibre-reinforced polymer (FRP) composites in enhancing the structural performances of glulam beams, with particular reference on their flexural and shear strength. In fact FRP reinforcements could be used to strengthen existing structures or to reduce …
Effect of surface treatments on the bond strength of CAD/CAM fiberglass posts
2018
Background There is no ideal protocol for the surface treatment of fiber posts, especially when using a computer-aided design/computer-aided manufacturing (CAD/CAM) experimental fiberglass block. The purpose of this study was to evaluate the bond strength of a CAD/CAM customized glass fiber post and core after applying different surface treatment techniques. Material and methods Forty premolars were prepared to receive a customized CAD/CAM glass-fiber post and core obtained from an experimental block of glass fiber and epoxy resin. The specimens were randomly distributed in 4 groups (n=10) according to the post and core surface treatment: ETH - 70% ethanol; HP - 24% hydrogen peroxide for 1 …
Experimental in situ behaviour of unreinforced masonry elements retrofitted by pre-tensioned stainless steel ribbons
2014
Abstract The results of in situ tests carried out on unreinforced and reinforced poor rubble masonry full-scale walls in the earthquake prone Messina (Italy) area are presented and discussed. This experimental research was aimed at the assessment of the in plane shear behaviour of ancient masonry strengthened with an innovative system for masonry and retrofitting of reinforced concrete element constituted by three-dimensional pre-tensioned stainless steel ribbons. A comparison between different strengthening configurations was made in order to characterise the behaviour of masonry panels under shear-compression load, focusing attention on the diagonal cracking failure mode. The effectivenes…
Collapsible intact soil stabilisation using non-aqueous polymeric vehicle
2020
Abstract This paper presents the results of an experimental study that had the goal of understanding the effects of treatment with polyethylene glycol (PEG)/nanolime mixtures on collapsible soil behaviour. In a previous study, the use of pure PEG offered a good improvement in the stability of collapsible soil, but the stabilisation effect only lasted for a limited time. To investigate the stabilisation potential of PEG/nanolime systems for collapsible sand, different mixtures were prepared at increasing nanolime weight ratios. The suitability of the stabilised soil was examined on the basis of collapsibility, oedometer, shear, and water vapour permeability tests, and through optical microsc…
Shear bond strength of orthodontic metal brackets to aged composite using three primers
2017
Background This study aimed to assess the effect of surface preparation with sandblasting and diamond bur along with the use of three primers on shear bond strength (SBS) of metal brackets to aged composite. Material and methods In this in vitro, experimental study, 60 Filtek Z250 composite discs were fabricated (10×2mm), immersed in distilled water for 24 hours and subjected to 5000 thermal cycles. They were randomly divided into two groups (n=30) of sandblasting with aluminum oxide particles for 10 seconds and surface roughening with bur. Each group was randomly divided into three subgroups (n=10) for use of Transbond XT, Assure Plus and Composite Primer. Metal brackets were bonded and th…
Experimental investigation of the influence of adhesion on the frictional conditions in the cutting process
1999
Abstract This paper presents the results of an experimental study on the influence of adhesion on the tribological characteristics of the tool-chip interface. It was established that under orthogonal cutting conditions both the high interface temperature and severe plastic deformation result in relatively strong adhesion between steel and uncoated carbide. In particular, the molecular–mechanical theory of friction was applied to estimate the shear strength of the local adhesive junction, and to divided the rake face friction into two terms—an adhesion term (the interfacial coefficient of friction) and the deformation term. It should be pointed out that the data obtained provide a new approa…
Shear strength of steel fiber reinforced concrete beams with stirrups
2006
The present paper proposes a semi-empirical analytical expression that is capable of determining the shear strength of reinforced concrete beams with longitudinal bars, in the presence of reinforcing fibers and transverse stirrups. The expression is based on an evaluation of the strength contribution of beam and arch actions and it makes it possible to take their interaction with the fibers into account. For the strength contribution of stirrups, the effective stress reached at beam failure was considered by introducing an effectiveness function. This function shows the share of beam action strength contribution on the global strength of the beam calculated including the effect of fibers. T…