4 research outputs found
Testing Calibration Issues in Resistance Drilling Applied to Timber Elements
No full textResistance drilling devices are commonly used for the onsite inspection of wood and timber
structural components in existing buildings. Although they provide a measure related to the
density variation along a section of an element, results are used mainly qualitatively, due to
several parameters that affect the computed values.
In this paper, several new and old timber elements, taken from the dismantling of original roofs
from a large existing historical building in northern Italy, are tested through a series of ND
(non-destructive), SD (semi-destructive) and destructive testing procedures. Various wood
species (spruce, fir, larch, oak, elm, pine) are taken into consideration.
Among the applied testing methods (visual inspection, resistance drill, ultrasonic, needle
penetration, radar, lab tests bending/compression), not all reported here, a focus on the
resistance drill tests results is addressed, to evaluate the influence of consumption of the needle
tip on the amplitude output. This was done by correlating the drillings to a reference sample
on each test position to obtain data with an enhanced quantitative content. From the visual old
timber elements grading, SD tests execution and successive element strength characterization
through laboratory tests, it finally emerged the need for proper calibration of assessment
methodologies through the application of a combined approach, in order to achieve more
reliable results
Influence of Moisture Content on the Application of ND and MD Tests to Various Species of Timber Elements
No full textVariations in environmental conditions can affect the structural performance of
timber components and constructions. Especially in case of historic masonry buildings, where
timber elements can be found either in roof or floor structures, intrinsic defects (e.g., knots,
cracks, degradation), as well as the surrounding environmental conditions (e.g., temperature
and moisture) can play an important role in the assessment of the mechanical response of the
elements. In this connection, non-destructive (ND) and minor-destructive (MD) procedures are
used to investigate the onsite conditions of wood, which are commonly based on either tool
penetration resistance or wave transmission devices. In the paper, the influence of moisture
content (MC) measured with various devices on a series of both old and new timber elements
was compared. The elements made of various wood species (mainly red fir, but also white fir,
pine and larch) were subjected to laboratory ND and MD testing by three research groups.
Results showed the low influence of the MC on MD tests (i.e., resistance drilling and pin
penetration) in comparison to the ND (i.e., sonic/ultrasonic) ones. Correlation relationships
are provided, which illustrate and approximatively quantify the effect of MC for the
experimentally investigated conditions and test equipment
Testing Calibration Issues in Resistance Drilling Applied to Timber Elements
No full textResistance drilling devices are commonly used for the onsite inspection of wood and timber structural components in existing buildings. Although they provide a measure related to the density variation along a section of an element, results are used mainly qualitatively, due to several parameters that affect the computed values. In this paper, several new and old timber elements, taken from the dismantling of original roofs from a large existing historical building in northern Italy, are tested through a series of ND (non-destructive), SD (semi-destructive) and destructive testing procedures. Various wood species (spruce, fir, larch, oak, elm, pine) are taken into consideration. Among the applied testing methods (visual inspection, resistance drill, ultrasonic, needle penetration, radar, lab tests bending/compression), not all reported here, a focus on the resistance drill tests results is addressed, to evaluate the influence of consumption of the needle tip on the amplitude output. This was done by correlating the drillings to a reference sample on each test position to obtain data with an enhanced quantitative content. From the visual old timber elements grading, SD tests execution and successive element strength characterization through laboratory tests, it finally emerged the need for proper calibration of assessment methodologies through the application of a combined approach, in order to achieve more reliable results
Influence of titanium dioxide nanoparticles on 2,3,7,8-tetrachlorodibenzo-p-dioxin bioconcentration and toxicity in the marine fish European sea bass (Dicentrarchus labrax)
No full textThe present study investigated the influence of nano-TiO(2) (1 mg L(-1)) on 2,3,7,8-tetrachlorodibenzo-p-dioxin(2,3,7,8-TCDD) (46 pg L(-1)) bioconcentration and toxicity in the European sea bass (Dicentrarchus labrax) during 7 days in vivo exposure. A multimarkers approach was applied in different organs: detoxification in liver; innate immunity and pro-inflammatory response and adaptive immunity in gills and spleen; genotoxicity in peripheral erythrocytes and muscle. Bioconcentration of 2,3,7,8-TCDD in presence of nano-TiO2 was investigated in liver, skin and muscle as well as interaction between nano-TiO2 and organic pollutants in artificial sea water (ASW). Nano-TiO2 negatively influenced immune response induced by 2,3,7,8-TCDD in spleen but not in gills and reduced the DNA damage induced by 2,3,7,8-TCDD in erythrocytes. nano-TiO2 did not interfere with 2,3,7,8-TCDD detoxification and bioconcentration according to the observed no interaction of the nano-TiO2 with organic pollutants in ASW
