Experimental and numerical analysis of RC structure with two leaf cavity wall subjected to shake table

Onur Onat,Paulo B. Lourenço,Ali Koçak 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.5

This paper presents finite element (FE) based pushover analysis of a reinforced concrete structure with a two-leaf cavity wall (TLCW) to estimate the performance level of this structure. In addition to this, an unreinforced masonry (URM) model was selected for comparison. Simulations and analyses of these structures were performed using the DIANA FE program. The mentioned structures were selected as two storeys and two bays. The dimensions of the structures were scaled 1:1.5 according to the Cauchy Froude similitude law. A shake table experiment was implemented on the reinforced concrete structure with the two-leaf cavity wall (TLCW) at the National Civil Engineering Laboratory (LNEC) in Lisbon, Portugal. The model that simulates URM was not experimentally studied. This structure was modelled in the same manner as the TLCW. The purpose of this virtual model is to compare the respective performances. Two nonlinear analyses were performed and compared with the experimental test results. These analyses were carried out in two phases. The research addresses first the analysis of a structure with only reinforced concrete elements, and secondly the analysis of the same structure with reinforced concrete elements and infill walls. Both researches consider static loading and pushover analysis. The experimental pushover curve was plotted by the envelope of the experimental curve obtained on the basis of the shake table records. Crack patterns, failure modes and performance curves were plotted for both models. Finally, results were evaluated on the basis of the current regulation ASCE/SEI 41-06.

Calibration of the X-ray Diffraction Technique in Measuring In-service Stresses in Corrugated Steel Bars

Santiago Sánchez-Beitia,Daniel Luengas-Carreño,Paulo B. Lourenço 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.6

The X-ray diff raction technique for determining residual stresses in construction steels has been commonly used in the international scientifi c community for decades. Taking advantage of the concepts on which the technique is based, the authors have previously calibrated and used the technique for the in situ determination of the stress states of metallic structures in service. This article presents an advance in the latter utility by means of the laboratory calibration of the X-ray diff raction technique in corrugated steel. The interaction between radiation and steel is complex, so, in the scientifi c community, it is considered pertinent to resort to empirical and experimental calibration processes. Two bars of corrugated steel were subjected to increasing tensile loads. The load states introduced in the testing machine were compared with those determined by X-ray diff raction. The correlation between the values of the loads applied and those determined by the proposed technique is excellent. The experimental conditions of the calibration tests are precisely detailed so that they are easily reproducible. This work represents a necessary fi rst step in employing the technique in the buildings or civil works.

Macroscopic;Histological;and Microbiological Characterization of Contact Lesions at the Tibiotarsal Region of Broilers

Ricardo Cavani,Marcela da Silva Rubio,Khauston Augusto Pereira Alves,Lucas José, Luduverio Pizauro,Marita Vedovelli Cardozo,Paulo Lourenç,o Silva,Iran José, Oliveira Silva,Fernando Antô,nio Avila 한국축산식품학회 2022 한국축산식품학회지 Vol.42 No.1

Brazil is considered as a great broiler feet exporter;especially for the Chinese trade. Contact lesions at the tibiotarsal region are responsible for economic losses and there is no model for its classification;thereby this study presents a fast and practical grade system to be used in the poultry industry and proposes these lesion characterizations into three different grades. For this;correlation was made between macroscopic;histological findings and microbiological quantification (Escherichia coli;Staphylococcus spp.;Streptococcus spp. and sulphite-reducing clostridia) from contact lesions in the tibiotarsal region of 112 broiler carcasses;divided in four groups (n=28);accordingly to the lesion’s intensity. There were no significant differences in microbiological quantification among the groups (p>0.05) except for the grade 3 group;as grade 1 and 2 lesions were in the early stages and histopathological changes such as ulceration were not observed. In grade 3 lesion group;it was observed bacterial cocci grume and ulceration at the articular region and significantly higher microbiological count (p<0.05) for E. coli and Staphylococcus spp. In conclusion;the visual standard proposed in this work;correlated and confirmed by the histopathologic;and microbiologic characterization;allows to precise and fast ascertainment of the contact lesion grade in the tibiotarsal regions of broiler carcasses. Moreover;it should be highlighted that grades 1 and 2 alterations are not caused by an inflammatory process caused by pathogenic agents and should not be considered a public health risk.

Macroscopic, Histological, and Microbiological Characterization of Contact Lesions at the Tibiotarsal Region of Broilers

Ricardo Cavani,Marcela da Silva Rubio,Khauston Augusto Pereira Alves,Lucas José Luduverio Pizauro,Marita Vedovelli Cardozo,Paulo Lourenço Silva,Iran José Oliveira Silva,Fernando Antônio Avila 한국축산식품학회 2022 한국축산식품학회지 Vol.42 No.2

Brazil is considered as a great broiler feet exporter, especially for the Chinese trade. Contact lesions at the tibiotarsal region are responsible for economic losses and there is no model for its classification, thereby this study presents a fast and practical grade system to be used in the poultry industry and proposes these lesion characterizations into three different grades. For this, correlation was made between macroscopic, histological findings and microbiological quantification (Escherichia coli, Staphylococcus spp., Streptococcus spp. and sulphite-reducing clostridia) from contact lesions in the tibiotarsal region of 112 broiler carcasses, divided in four groups (n=28), accordingly to the lesion’s intensity. There were no significant differences in microbiological quantification among the groups (p>0.05) except for the grade 3 group, as grade 1 and 2 lesions were in the early stages and histopathological changes such as ulceration were not observed. In grade 3 lesion group, it was observed bacterial cocci grume and ulceration at the articular region and significantly higher microbiological count (p<0.05) for E. coli and Staphylococcus spp. In conclusion, the visual standard proposed in this work, correlated and confirmed by the histopathologic, and microbiologic characterization, allows to precise and fast ascertainment of the contact lesion grade in the tibiotarsal regions of broiler carcasses. Moreover, it should be highlighted that grades 1 and 2 alterations are not caused by an inflammatory process caused by pathogenic agents and should not be considered a public health risk.

Sensory neurons and osteoblasts: close partners in a microfluidic platform

Neto, Estrela,Alves, Cecí,lia J.,Sousa, Daniela M.,Alencastre, Inê,s S.,Lourenç,o, Ana H.,Leitã,o, Luí,s,Ryu, Hyun R.,Jeon, Noo L.,Fernandes, Rui,Aguiar, Paulo,Almeida, Ra Oxford University Press 2014 Integrative biology Vol.6 No.6

<P>Innervation has proven to be critical in bone homeostasis/regeneration due to the effect of soluble factors, produced by nerve fibers, associated with changes in the activity of bone cells. Thus, in this study, we have established and characterized a coculture system comprising sensory neurons and osteoblasts to mimic the <I>in vivo</I> scenario where nerve fibers can be found in a bone microenvironment. Embryonic or adult primary dorsal root ganglion (DRG) and MC3T3-E1 osteoblastic cells were cocultured in compartmentalized microfluidic platforms and morphological and functional tests were performed. The time of adhesion and readout of axonal outgrowth were improved by the alignment of DRG with the axis of microgrooves, which showed to be a crucial step for the designed experiments. Cocultures of entire DRG from adult origin with osteoblasts were performed, showing extended DRG projections towards the axonal compartment, reaching osteoblastic cells. Immunocytochemistry showed that the neurites present within the osteoblastic compartment were immunoreactive to synapsin and calcitonin gene-related peptide suggesting the presence of specialized structures involved in this crosstalk. This evidence was further confirmed by electron microscopy where varicosities were detected as well as electron dense structures in neurite membranes. Aiming to mimic the properties of tissue extracellular matrices, MC3T3-E1 cells were seeded in the axonal side upon laminin, collagen or within 3D functionalized alginate matrices and axonal outgrowth was clearly observed. In order to analyze and quantify data with reproducible image analysis, a semi-automated algorithm was also developed. The collagen and laminin substrates displayed a higher amount of axons reaching the axonal side. Overall, the established method revealed to be a suitable tool to study the interaction between the peripheral nervous system and bone cells in different contexts mimicking the <I>in vivo</I> scenario.</P>