In the last two decades, high-rise timber buildings have been built using the glulam truss system, even with limited openings. Moment-resisting timber frames (MRTF) with semi-rigid beam-to-column ...connections can be an architecture-friendly way to provide a load-carrying system to vertical and horizontal loads for timber buildings. In these structures, connections of adequate ductility are crucial to ensure robustness and energy dissipation. This paper presents a review of the main types of timber beam–column moment connections with improved ductility and proposes to carry out a ductility assessment of these connections based on the most relevant ductility factors. Joints have a significant influence on the global performance of MRTF, and the application of ductile connections have improved the mechanical parameters of the timber frame. The reinforced bolted slotted-in steel plate and glued-in rods connections have similar mechanical performance, with high rotation capacity and good ultimate moment, but exhibited different failure modes under cyclic loading. The connections were classified within ductility classes. In general, the glued-in steel rods presented better results because of the high influence of steel profiles in the connection yielding. Despite the excellent mechanical behavior, the reinforced bolted slotted-in steel plate connections presented medium ductility values.
Although there are several steel-to-timber joint types, there is still a lack of studies that more precisely characterize the components in the interaction between steel and timber in compression. ...Thus, this work aims to characterize the steel T-stub compressing the glued laminated timber (GLT) parallel to the grain component, focusing on formulating analytical expressions for design resistance, stiffness coefficient and deformation capacity. In order to validate the analytical models and increase the reliability of the component method, an experimental campaign was conducted through compression tests on 90 specimens composed of steel T-stubs with five different flange thicknesses under full and partial compression. It was identified that although GLT has lower compressive strength and lower stiffness than steel, the main failure mode in specimens studied was T-stub flange yielding. The proposed formulations were consistent with the experimental results and it can be used to predict the structural behavior of this component. The application of the component analytical variable elastic approach to a semi-rigid connection showed an increase in the accuracy for predicting its moment resistance.
•The main failure mode observed was the T-stub flange yielding, due to small stiffness of the flange and to the concentration of stresses in the central region of the timber.•The component is characterized by proposing equations for resistance, stiffness coefficient, and deformation capacity. The precision of these parameters has been improved compared to experimental results and to equations proposed by other authors for joints with similar geometry.•Experimental evaluation of the steel T-stub compressing timber parallel to the grain component carried out with five different T-stub thicknesses and timber subjected to full and partial compression.
Despite the growing use of cross-laminated timber (CLT) panels in the construction industry, their behaviours under weather conditions, especially cyclic moisture which generated additional strains, ...requires further investigation. To address this gap, an extensive experimental campaign was carried out to evaluate CLT elements, in which strains are measured, under cyclic moisture changes, using Digital Image Correlation (DIC). In this way, the effects of cyclic humidity changes on amplitude and distribution of strains on four different configurations of CLT panels, divided based on the free flow direction of moisture, are explained. Regarding RH cycle tests, CLT specimens were conditioned in climatic chambers for 324 days at constant temperature 20 (°C) with a humidity cycle varying every 21 days between 30% and 90%, getting constant at 65% after the first 142 days. Results show that, in the main face, drying periods present tensile strain while wetting periods present compressive strains in the longitudinal direction. But, in the tangential direction, restrained strains tend to reduce significantly from first to last drying cycles for all test configurations. Moreover, in the lateral face, drying periods present tensile strains while wetting periods present compressive strains in the tangential direction. Experimental results confirmed that the ratio between tangential and longitudinal directions tends to decrease with the number of RH cycles, and successive RH cycles do not cause cumulative strains on CLT panels.
•Experimental work aimed to measure strains induced in CLT panels by cyclic moisture changes using DIC.•CLT specimens conditioned for 324 days at constant T= 20 (°C) with a RH cycle varying every 21 days between 30% and 90%.•Drying periods present tensile strain while wetting periods present compressive strains in the longitudinal direction.•But, in the tangential direction, restrained strains tend to reduce significantly from first to last drying cycles.
Computer Vision, Digital Image Processing, and Digital Image Analysis can be viewed as an amalgam of terms that very often are used to describe similar processes. Most of this confusion arises ...because these are interconnected fields that emerged with the development of digital image acquisition. Thus, there is a need to understand the connection between these fields, how a digital image is formed, and the differences regarding the many sensors available, each best suited for different applications. From the advent of the charge-coupled devices demarking the birth of digital imaging, the field has advanced quite fast. Sensors have evolved from grayscale to color with increasingly higher resolution and better performance. Also, many other sensors have appeared, such as infrared cameras, stereo imaging, time of flight sensors, satellite, and hyperspectral imaging. There are also images generated by other signals, such as sound (ultrasound scanners and sonars) and radiation (standard x-ray and computed tomography), which are widely used to produce medical images. In animal and veterinary sciences, these sensors have been used in many applications, mostly under experimental conditions and with just some applications yet developed on commercial farms. Such applications can range from the assessment of beef cuts composition to live animal identification, tracking, behavior monitoring, and measurement of phenotypes of interest, such as body weight, condition score, and gait. Computer vision systems (CVS) have the potential to be used in precision livestock farming and high-throughput phenotyping applications. We believe that the constant measurement of traits through CVS can reduce management costs and optimize decision-making in livestock operations, in addition to opening new possibilities in selective breeding. Applications of CSV are currently a growing research area and there are already commercial products available. However, there are still challenges that demand research for the successful development of autonomous solutions capable of delivering critical information. This review intends to present significant developments that have been made in CVS applications in animal and veterinary sciences and to highlight areas in which further research is still needed before full deployment of CVS in breeding programs and commercial farms.
•We describe cases of envenoming by Crotalus bites in the Brazilian Amazon.•A total of 70,816 snakebites were recorded in the Amazon Region.•Rattlesnake bites incidence was positively associated to ...tree canopy loss and altitude.•The distribution was irregular between the municipalities in the Amazon State.
Crotalus bites are considered a public health problem especially in Latin America. This study was performed to describe the epidemiology, spatial distribution and environmental determinants of Crotalus durissus bites in the Brazilian Amazon. Crotalus durissus envenomings official database included cases reported from 2010 to 2015. A total of 70,816 snakebites were recorded in the Amazon Region, 3058 (4.3%) cases being classified as crotalid, with a mean incidence rate of 11.1/100,000 inhabitants/year. The highest mean incidence rates were reported in Roraima, Tocantins and Maranhão. Area covered by water bodies, precipitation and soil humidity were negatively associated to rattlesnake encountering. Rattlesnake bites incidence was positively associated to tree canopy loss and altitude. In the Amazon, severe manifestations at admission, delayed medical assistance, lack of antivenom administration and ages ≥61 and 0–15 years were predictors of death in C. durissus snakebites. Spatial distribution of rattlesnake bites across the Brazilian Amazon showed higher incidence in areas of transition from the equatorial forest to the savanna, and in the savanna itself. Such results may aid focused policy-making in order to mitigate the burden, clinical complications and death as well as to manage Crotalus rattlesnake populations in the Brazilian Amazon.
The study proposes to analyze the distribution of bending moment due to live load in curved bridges that have undergone a process of widening, considering the influence of concrete’s strength ...variation. The results show that the bending moment redistribution is more significant the higher the stiffness in the widenings. In addition, the redistribution induced by the variation of stiffness depends on the live load positioning but, generally, it results in the migration of bending moments to the stiffer regions, relieving the original girders. The curvature did not significantly alter the response induced by the stiffening of the widened segments. Also, the divergences found between the MEF and the V-load Method results for models with uniform and variable stiffness were similar. Finally, the Modification Factors (MF) proved to be more sensitive to the influence of curvature than to the concrete strength in the widenings.
resumo: Esta pesquisa propõe analisar a distribuição de momentos fletores devido à carga móvel entre longarinas de pontes curvas de concreto armado que passaram por um processo de alargamento da superestrutura. Como principais conclusões foi constatado que a redistribuição de momentos é tanto mais significativa quanto mais elevada for a rigidez dos alargamentos. Ademais também foi observado que a redistribuição induzida pela variação da rigidez está condicionada à posição do carregamento móvel, porém, em geral, resultam na migração de esforços para os trechos mais rígidos, aliviando as longarinas originais. Constatou-se ainda que a variação da curvatura pouco altera a redistribuição de esforços induzida pelo aumento da rigidez no alargamento. Ademais, as divergências entre os resultados do MEF e do Método V-Load para os modelos com rigidez variável não divergiram significativamente daqueles obtidos nos modelos de rigidez constante. Por fim, os Fatores de Modificação (FM) mostraram-se mais sensíveis à variação do raio de curvatura do que à resistência do concreto nos alargamentos.
The present study focuses on comparative parametric analysis of curved precast concrete bridges using straight and curved I-girders. The live load bending moment distribution for girders was studied ...using the bridge curvature and its relationship with the results obtained for a straight bridge. FEM 3D models were developed with restrictions on the transverse live load positions and with two different load models types: HL-93 (AASHTO) and TB-450 (NBR 7188, 2013). The parametric analysis results were calculated using the Modification Factor (MF) and the Bending Moment Distribution Factor (BMDF), calculated from the structural analysis of each model at the midspan. Globally, an increase was found in the total bending moment for the curved bridge models in relation to the straight bridge. In the examples herein studied, the larger the bending radius, the larger the maximal bending moment in the bridge center. For the external girders, the MF increases with the increase of the L/R. For the internal ones, the MF decreases with the increase of the L/R. In addition, the occurrence of “Load Shift” was different from the rigid body behavior, for there was demonstrated a different bending moment variation between external girder (G1) in relation to its adjacent (G2). Therefore, the structural behavior of straight (SG) and curved girders (CG) was analyzed, revealing that, in the SG, a significant gap occurred in the BMDF between G1 and G2 girders for all curvatures. For L/R = 0.6, it caused a difference of 17.8% in the BMDF between the G1 and G2 girders, while on the curved girders, a difference of only 6.6% was found.
resumo: o presente estudo foca na análise paramétrica comparativa de pontes curvas utilizando utilizando longarinas retas e curvas pré-moldadas. As análises foram baseadas na distribuição transversal de momento fletor para a longarinas, na variação da curvatura da ponte e na relação desses parâmetros com os resultados obtidos em uma ponte reta. Foram desenvolvidos FEM 3D models com restrições nas posições transversais da carga-móvel e com dois tipos diferentes de modelos de carga: HL-93 e NBR 7187. Os resultados da análise paramétrica foram determinados utilizando o Fator de Modificação (FM) e o Fator de Distribuição de Momento Fletor (FDMF), calculadas a partir da análise estrutural de cada modelo na posição longitudinal do meio do vão. No âmbito global, contatou-se um aumento do momento fletor total nos modelos de ponte curva em relação à reta. Nos exemplos estudados, quanto maior o raio de curvatura, maior foi o momento fletor máximo no meio do vão da ponte. O valor de FM varia linearmente. Para as longarinas externas o FM aumenta com o aumento do L/R, já para as internas, o FM diminui com o aumento do L/R. Além disso, foi comprovada a ocorrência de “Load Shift” diferente do comportamento de corpo rígido, tendo em vista a variação diferenciada de momento fletor para a longarina externa G1 em relação a sua adjacente G2. Constatou-se uma diferença considerável de comportamento estrutural entre as longarinas retas e curvas, tendo em vista que nas SG ocorreu uma diferença significativa de FDMF entre a longarina G1 e a G2 para todas as curvaturas, o que não ocorreu para as CG. Para L/R=0.6, observou-se uma diferença de 17.8% no FDMF entre as longarinas G1 e G2 retas, já nas longarinas curvas, a diferença foi de apenas 6.6%.
Abstract
With agriculture rapidly becoming a data-driven field, it is imperative to extract useful information from large data collections to optimize the production systems. We compared the efficacy ...of regression (linear regression or generalized linear regression GLR for continuous or categorical outcomes, respectively), random forests (RF) and multilayer neural networks (NN) to predict beef carcass weight (CW), age when finished (AS), fat deposition (FD), and carcass quality (CQ). The data analyzed contained information on over 4 million beef cattle from 5,204 farms, corresponding to 4.3% of Brazil’s national production between 2014 and 2016. Explanatory variables were integrated from different data sources and encompassed animal traits, participation in a technical advising program, nutritional products sold to farms, economic variables related to beef production, month when finished, soil fertility, and climate in the location in which animals were raised. The training set was composed of information collected in 2014 and 2015, while the testing set had information recorded in 2016. After parameter tuning for each algorithm, models were used to predict the testing set. The best model to predict CW and AS was RF (CW: predicted root mean square error = 0.65, R2 = 0.61, and mean absolute error = 0.49; AS: accuracy = 28.7%, Cohen’s kappa coefficient Kappa = 0.08). While the best approach for FD and CQ was GLR (accuracy = 45.7%, Kappa = 0.05, and accuracy = 58.7%, Kappa = 0.09, respectively). Across all models, there was a tendency for better performance with RF and regression and worse with NN. Animal category, nutritional plan, cattle sales price, participation in a technical advising program, and climate and soil in which animals were raised were deemed important for prediction of meat production and quality with regression and RF. The development of strategies for prediction of livestock production using real-world large-scale data will be core to projecting future trends and optimizing the allocation of resources at all levels of the production chain, rendering animal production more sustainable. Despite beef cattle production being a complex system, this analysis shows that by integrating different sources of data it is possible to forecast meat production and quality at the national level with moderate-high levels of accuracy.
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