41,684 research outputs found
Mechanical characterization of timber in structural sizes: bending and compression tests
This paper presents the results obtained in a series of tests on Pinus Pinaster Ait. timber specimens, using the prEN408:2000, to estimate the local and global Young’s modulus and strength both in bending and compression parallel to the grain. The results obtained are compared with the values presented in the Portuguese Nationally Determined Parameters of Eurocode 5, for the quality classes assign by Portuguese Standard NP4305:1994 by visual grading
Recursion relations for multi-gluon off-shell amplitudes on the light-front and Wilson lines
We analyze the off-shell scattering amplitudes in the framework of the
light-front perturbation theory. It is shown that the previously derived
recursion relation between tree level off-shell amplitudes in this formalism
actually resums whole classes of graphs into a Wilson line. More precisely, we
establish a correspondence between the light-front methods for the computation
of the off-shell amplitudes and the approach which makes use of the matrix
elements of straight infinite Wilson lines, which are manifestly gauge
invariant objects. Furthermore, since it is needed to explicitly verify the
gauge invariance of light-front amplitudes, it is demonstrated that the Ward
identities in this framework need additional instantaneous terms in the
light-front graphs.Comment: 26 pages, a few figure
Behaviour of traditional Portuguese timber roof structures
The aim of this paper is to present the results of a structural analysis of common trusses traditionally used in roof construction in Portugal. The study includes the results of a preliminary survey intending to assess the geometry, materials and on site pathologies, as well as a twodimensional linear elastic static and dynamic analysis. The trusses behaviour under symmetric and non-symmetric loads, the king post/tie-beam connection, the stiffness of the joints and the incorrect positioning of the purlins, were some of the structural aspects that have been investigated
Modelling of timber joints in traditional structures
Original unstrengthened timber connections and the effects of different strengthening techniques
have been evaluated experimentally with tests on full-scale birdsmouth joints. Experimental results
show that structural response of traditional timber connections under cyclic loading cannot be
represented by common constraint models, like perfect hinges or rigid joints, but should be using
semi-rigid and friction based models. A research program has investigated the behaviour of old
timber joints and examined strengthening criteria. The main parameters affecting the mechanical
behaviour of the connection have been singled out. A synthetic model of cyclic behaviour has been
adapted on the basis of experimental results
Experimental analysis of original and strengthened traditional timber connections
Tests on full-scale unstrengthened connections were performed under monotonic and cyclic loading. Attention has been principally focused on the birdsmouth joint, because of its common use in practice. Different strengthening solutions with metal elements have been evaluated
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