•Riveted bolt shear connectors used in composite cold-formed steel was investigated as load transfer device.•Numerical study was carried out with validation already proven in the ...literature.•Experimental and numerical results of the riveted bolt connectors were compared with design equations.•An analytical formulation of concrete bearing failure was proposed.
This paper presents a study of the behaviour of riveted bolt shear connectors applied in composite columns of cold-formed steel sections (CFS) filled with concrete. The use of these devices as shear connectors is an innovative solution and of great practical interest due to several advantages, such as: welding elimination; assemblage procedure performed outside of the closed-box CFS; low cost and do not require specialized workmanship for its installation. The experimental campaign consisted of two series of push tests performed with the purpose to evaluate the behaviour of these connectors applied in composite columns. The numerical model was calibrated with the tested specimens, achieving a good correlation between the numerical and experimental outputs. Then, a parametric study was carried out. It was observed that the strength capacity of the connectors was governed by the concrete bearing failure and other failures types, such as bolt shear and steel tube bearing were not observed. Based on this, an analytical model that considers the local concrete confinement effect was proposed to concrete bearing failure capacity. With an acceptable variation, the results obtained by this proposed procedure were satisfactory when compared to the numerical ones, as well as better than the standardized calculation procedure, which presented a greater variation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Agricultural abandonment is a major driver of change in rural landscapes. Assumed to provide beneficial results to the environment and the conservation of biota, rural abandonment triggers landscape ...and biotic homogenization and loss of valuable species and habitats. This article focuses on the ecological effects and conservation challenges of shifts in extensive grazing regimes on marginal pastureland of Mediterranean mountains. We conceptualize a navigated socioecological transition toward conservation‐oriented management after the collapse of historical land systems. The article provides examples from the LIFE+ project “Higro,” developed in mountainous protected areas in Portugal, of how management for conservation could sustain disturbance‐dependent habitats. We argue that actively and regularly managing large habitat areas should be envisaged as a short‐term approach to limit the immediate effects of rural abandonment. A gradual integration of conservation targets with other activities in changing rural economies is necessary to foster long‐term conservation of species and habitats, building on the link between conservation‐oriented habitat management and ecosystem services in rural landscapes. Conservation goals should run alongside recovery of social systems and innovation applied to traditional sources of income. This parallel development would contribute to building up social‐ecological resilience by maintaining a diversity of social and ecological capital in rural areas.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
•The column base connection was evaluated through an experimental program.•Epoxy and cement grouts were evaluated in column base connections.•Stress-strain curves for the epoxy grout were defined ...through compression tests.•Anchor rods presented double bending curvature on the failure.•Epoxy grout improved the performance of column base connections.
The column base connection is responsible for transferring the superstructure actions to the foundation and consists, typically, of a base plate and threaded steel bars or anchor rods. A grout layer is used for filling the clearance between the base plate and the top of concrete block, usually composed of a fluid-based hydraulic cementitious material with specific mechanical properties as high strength, negligible shrinkage, brittleness and delayed curing. Epoxy-based materials may be used as a more efficient material on applications with impact and dynamic loads or when a quick cure is required but as it is a recently developed material, its adoption occurs empirically. There are few studies about the use of this material in base column connections and mainly about its contribution to shear resistance due to the higher strength of this material. The international codes of steel and composite structures do not provide design guidance for the application of this material in base connections. Because of this lack of information, this work presents an experimental campaign about the behaviour of regular column bases, with a pre-installed steel anchor rod and grout layer composed of cement and epoxy materials, subject to monotonic shear forces.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper presents a study on the development of a novel shear connector for usage on cold-formed steel–concrete composite beams. The connector consists of a bolt fixed to the steel profile by means ...of a tubular rivet with inner thread and can be installed with a single access, allowing usage on tubular sections. Four push-out tests and four full-scale beam tests were conducted, two with friction between the steel section and the slab and two without friction. A numerical analysis was also conducted to assess whether the beam behaviour could be simulated in the finite element commercial code ABAQUS. It was noted that the shear connectors were extremely flexible and presented very large slips. The connectors also presented enough strength to allow for the construction of composite beams with adequate shear interaction between the slab and the steel beam without an excessive number of connectors. Due to the high flexibility of the connectors, even though the beam was designed considering full shear interaction between the slab and the steel section, the observed values of strength and stiffness were not as high as calculated. Design codes should have their procedures reviewed to consider this flexibility, as only a strength requirement proved to be unsuitable, indicating that full shear interaction was not achieved. It was also observed that the presence of friction increased the interaction level of the beams.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Resumo Este trabalho apresenta uma análise da influência do tipo de combate a incêndio nas temperaturas desenvolvidas em um compartimento utilizado pelo Corpo de Bombeiros Militar de Minas Gerais ...(CBMMG) em seus treinamentos. Os tipos de combate variaram com o modo de aplicação de água em pulsos simples, dois pulsos ou pulsos mais longos. Os resultados demonstraram que os treinamentos representam bem os incêndios reais em ambientes construídos com as fases de início do incêndio e sua propagação, inflamação generalizada (flashover) e pós-flashover. Observou-se que a taxa de aplicação de água influencia inversamente no tempo de duração do incêndio e na temperatura da região onde os combatentes se localizam. Foram realizados também ensaios sem intervenção e constatou-se que não há uma diferença significativa nas temperaturas máximas atingidas em comparação com os treinamentos normais. Os ensaios realizados no compartimento também demonstraram que ele pode ser utilizado para estudo de elementos construtivos e estruturais em situação de incêndio.
Abstract This paper presents an analysis of the influence of the type of firefighting technique at temperatures developed in a compartment used by the Minas Gerais Firefighting Department - CBMMG, Brazil, in its firefighting training. The types of firefighting varied according to the mode of deployment of water in simple pulses, two pulses or longer pulses. The results showed that the training appropriately represents real fires in buildings, presenting the fire ignition and growth phases, flashover and after flashover. The study showed that the rate of water application inversely affects the duration of the fire and the temperature in the region where the firefighters are located. Tests were also performed without intervention and showed that there is no significant difference in the maximum temperatures reached compared to normal training. The tests performed in the compartment also showed that they can be used for the study of building and structural elements in fire situations.
Se describe una nueva asociación (Sagino procumbentis-Sibthorpietum europaeae) de vegetación fontinal (clase Montio fontanae-Cardaminetea amarae) de los territorios temperados submediterráneos del ...Noroeste de Portugal, para incluir a las comunidades herbáceas perennes dominadas por Sagina procumbens y Sibthorpia europaea. En este trabajo, se presentan los datos florísticos, sinecológicos y biogeográficos que apoyan a la propuesta de este nuevo sintaxon.
A new phytosociological association of perennial nitrophilous vegetation is described from submediterranean mountain areas of North-Western Iberian Peninsula. Geranio lusitanici-Scrophularietum ...herminii ass. nova (class Artemisietea vulgaris) is physiognomically predominated by Scrophularia herminii and its individuality is based on the two nominal taxa (Scrophularia herminii and Geranium pyrenaicum subsp. lusitanicum), both endemic to the North-Western Iberian Peninsula. In this paper, the new association is fully characterised and distinguished from other perennial nitrophilous vegetation types in the territory in terms of its floristic composition, synecologic requirements, syntaxonomy, chorology and biogeography.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK