1,723 research outputs found
Light timber framed wall under fire: effect of the load and cladding
Light Timber Frame Walls are made of solid timber elements and are usually protected by cladding materials
(gypsum). This investigation finds the effect of different load levels and cladding systems on the fire resistance.
The timber frame structure is made with three studs and two rails, and will be analysed with two different
protection levels. The computational model includes the thermal analysis under standard fire and a sequential mechanical analysis with time increments. Both, thermal and thermo-mechanical models are validated against experimental results developed in the reduced scale and full scale. The timber frame structure is deemed to have failed when it is no longer supporting the test load. The results are also compared with the failure criteria used for the experimental tests. The timber frame is deformed and all simulated models attained the global bucking instability mode, with studs moving to the outside of the furnace, due to the effect of load and charred layer. The fire resistance of a double-layered light timber frame wall is higher than a single-layered, and both decrease with the load level. This ability is reduced by 46%, on average for all load levels, when using only one gypsum layer. A new formula is proposed to determine the fire resistance, based on the load level and cladding systems. The fire resistance of the specimens with two layers of gypsum plates decreases faster than the specimens with one layer of gypsum, with respect to the increase of the load level.info:eu-repo/semantics/publishedVersio
The fire resistance of light timber frame walls with different load levels and cladding layers
Lightweight Timber frame walls (LTFW) are commonly used in residential buildings due to their
light weight and low construction costs. LTFW are made with solid wood members (studs and
tracks) used on buildings, for load-bearing and partition walls. The assemblies are made with
solid stud wood vertical members, usually separated by 400 to 600 mm. The cladding for internal
walls may be developed by wood panels, composite panels and or gypsum panels. The number
of protection layers and insulation materials used in the cavity of the wall depends on the thermal
and acoustic efficiency required to the LTFW at room temperature, but also depends on the
required fire rating of LTFW.info:eu-repo/semantics/publishedVersio
Liouville type theorems for stationary Navier-Stokes equations with Lebesgue spaces of variable exponent
In this article we study some Liouville-type theorems for the stationary 3D
Navier-Stokes equations. These results are related to the uniqueness of weak
solutions for this system under some additional information over the velocity
field, which is usually stated in the literature in terms of Lebesgue, Morrey
or BMO^--1 spaces. Here we will consider Lebesgue spaces of variable exponent
which will provide us with some interesting flexibility
Effect of Undernutrition and Obesity on Clinical Outcomes in Adults with Community-Acquired Pneumonia
Malnutrition comprises two groups of conditions: undernutrition and overweight or obesity. It has been associated with a high risk of contracting infectious diseases and with elevated mortality rates. Community-acquired pneumonia (CAP) is one of the most common infectious diseases worldwide and its prognosis is affected by a large number of recognizable risk factors. This narrative review updates the information on the impact of malnutrition, including both undernutrition and obesity, on the risk and prognosis of adults with CAP. Studies of CAP that have evaluated undernutrition have applied a variety of definitions when assessing the nutritional status of patients. Undernutrition has been associated with unfavorable clinical outcomes, such as prolonged hospital stay, need for intensive care unit admission, and mortality; in contrast, most published studies have found that increased body mass index is significantly associated with higher survival in patients with CAP. However, some authors have presented divergent results, mainly in relation to the etiology of CAP (bacterial versus viral). Influenza infection, caused by influenza A (H1N1) pdm09, has been associated with worse prognosis in obese patients. The current data underscore the need for larger studies to examine the physiological mechanisms that explain the differential impact of malnutrition on outcomes. Achieving a better understanding may help to guide the design of new interventions to improve prognosis
Some remarks about the stationary Micropolar fluid equations: existence, regularity and uniqueness
We consider here the stationary Micropolar fluid equations which are a
particular generalization of the usual Navier-Stokes system where the
microrotations of the fluid particles must be taken into account. We thus
obtain two coupled equations: one based mainly in the velocity field u and the
other one based in the microrotation field . We will study in this work
some problems related to the existence of weak solutions as well as some
regularity and uniqueness properties. Our main result establish, under some
suitable decay at infinity conditions for the velocity field only, the
uniqueness of the trivial solution
Fire analysis of timber-framed walls lined with gypsum
This investigation analyses the influence of the depth and the distance between studs
on the fire resistance of lightweight timber-framed (LTF) walls lined with gypsum plasterboards.
The simplified model used to determine the fire resistance in Eurocode EN 1995-1-2 provides very
conservative values, as few parameters are considered. The new generation of Eurocode EN 1995-1-2
includes an upgrade of the simplified model, allowing us to predict the fire resistance of LTF wall
assemblies more accurately. This separating function method considers the number, the thickness
and the material of the protection layers, but does not explicitly consider the variation of the depth
and the distance between the studs for the calculation of the insulation time of the assembly, besides
including some limitations for both parameters. To demonstrate the influence of these parameters,
36 numerical simulations were carried out using the finite element method previously validated
with experimental tests. The results obtained from the parametric analyses confirmed that such
parameters affect the fire resistance of the LTF wall assemblies in a significant way. In addition, the
results revealed an important contribution in the study of LTF wall assemblies against fire resistance,
demonstrating the need for including extra geometric parameters in the simplified model in order to
increase the accuracy of current models.info:eu-repo/semantics/publishedVersio
- …