2,320 research outputs found
On the design of timber bolted connections subjected to fire
Paper 121Current research at the University of Canterbury is investigating the application of Johansen’s yield
equations to the prediction of the failure strength of bolted connections in fire conditions. A series
of single bolted connections using steel side plates have been heated at constant temperature for
several hours, then loaded to failure. The failure loads have been used to determine the embedment
strength of the joints at various temperatures over a range of temperatures from ambient to 300°C.
These temperature-dependent embedment strengths have also been used in the Johansen’s equations
for wood-steel-wood and wood-wood-wood connections and compared with the results for single
bolted connections tested over a range of constant temperatures. Comparisons have also been made
with the results of several similar connections tested in fire conditions and show considerable
promise for predicting failure of such joints
Feasibility and Detailing of Post-tensioned Timber Buildings for Seismic Areas
Paper 53This paper describes the structural design and selection of construction
detailing for low-rise multi-storey timber buildings using a new and exciting structural
timber system. This system, originally developed for use with pre-cast concrete,
combines the use of un-bonded post-tensioning techniques and additional sources of
energy dissipation. This system eliminates residual displacement, while greatly reducing
the damage to structural members during a significant seismic event. The paper shows
how this new structural system can be used with large size structural timber members
manufactured from laminated veneer lumber (LVL) or glulam timber, for use in multistorey
buildings, with lateral load resistance provided by post-tensioned structural timber
frames or walls, separately or in combination.
An extensive on-going research program at the University of Canterbury, New Zealand
has tested a wide range of beam-to-column, wall-to-foundation and column-to-foundation
connections under simulated seismic loading, all giving excellent results.
As part of this contribution, a case study of the design methods, construction options, cost
and feasibility of a six storey timber office building in a moderate seismic area is carried
out. The structural design of this building allowed investigation of different methods of
structural analysis, and the development of many construction and connection details
offering feasibility of rapid construction. Total building cost was evaluated and compared
to equivalent steel and reinforced concrete options
Composite Wood–Concrete Structural Floor System with Horizontal Connectors
The concept of horizontal shear connection utilization on wood–concrete beams intends to be an alternative connection detail for composite wood–concrete decks. The volume of sawn-wood is over three times more expensive than concrete, in Brazil. In order to be competitive in the Brazilian market we need a composite deck with the least amount of wood and a simple and inexpensive connection detail. This research project uses medium to high density tropical hardwoods managed from the Brazilian Amazon region and construction steel rods. The beams studied are composed of a bottom layer of staggered wood boards and a top layer of concrete. The wood members are laterally nailed together to form a wide beam, and horizontal rebar connectors are installed before the concrete layer is applied on top. Two sets of wood–concrete layered beams with horizontal rebar connectors (6 and 8) were tested in third-point loading flexural bending. The initial results reveal medium composite efficiency for the beams tested. An improvement on the previously conceived connection detail (set with six connectors) for the composite wood–concrete structural floor system was achieved by the set with eight connectors. The new layout of the horizontal rebar connectors added higher composite efficiency for the beams tested. Further analysis with advanced rigorous numerical Finite Element Modeling is suggested to optimize the connection parameters. Composite wood–concrete decks can attend a large demand for pedestrian bridges, as well as residential and commercial slabs in the Brazilian Amazon. © 2014, The Author(s)
Damage classification after the 2009 L'Aquila earthquake using multinomial logistic regression and neural networks
Post-earthquake surveys represent a fundamental tool for managing the emergency phase after a strong earthquake. In Italy, the evaluation of the post-earthquake functionality of ordinary buildings is based on the AeDES forms (Agibilitá e Danno nell'Emergenza Sismica, or equivalently, Rapid Post-Earthquake Damage evaluation forms). This form includes information on the building and records of the observed damage classified according to type and intensity in 60 subclasses. Based on the observed damage and expert judgment, the buildings are clustered into six risk classes, from A to F. The assigned class is used to calculate the maximum economic reimbursement owed for the reconstruction or repair of the building. However, often the cluster assignment is not entirely objective due to the inherent responsibility associated with a less conservative assessment. This paper uses the data from the 2009 L'Aquila earthquake to develop classification models based on multinomial logistic regression (MLR) and artificial neural networks (ANN) calibrated with data theoretically less influenced by personal biases. The proposed models, particularly the MLR, are intended to support the decision-making of the evaluation team in future updates of the AeDES forms. This approach cannot substitute expert evaluation, which is always necessary for complex scenarios but may mitigate the impact of subjectivity and can provide an indication of the expected outcome of the survey
Charring rate for fire exposed X-Lam
Design of timber structures has been outlined in Eurocode 5. Notional charring rate for softwood and hardwood timber is given. For the performance of X-LAM panels in fire, only little information on charring is available and whether the fire behaviour of X-LAM is similar to homogenous timber panels has not yet been systematically analysed. This paper presents an overview of fire performance of X-LAM and evaluation of its resistance to elevated temperature as an element of structure in comparison to homogeneous timber panels. Numerical study has been carried out based on available experimental results. Charring rates for X-LAM panels obtained from experimental results are compared with those obtained from Eurocode 5 and proposed simplified model
Low-Noise Ku-Band Receiver Frontend with Switchable SIW Filters for Cubesat Applications
This paper proposes a low-noise receiver frontend
for nanosatellite and Cubesat platforms. The frontend is composed by a Low-Noise Amplifier (LNA) and two Substrate
Integrated Waveguide (SIW) filters, providing a frequency reconfigurability to the system. The two filters operate in the 13 and in
the 14 GHz uplink bands, and are selected by means of a pair of
solid-state SPDT switches. As a results, 15.5 dB gain with 2.4 dB
noise figure for the 13 GHz configuration and 17.8 dB gain with
2.3 dB noise figure for the 14 GHz configuration are obtained.
This work is important since demonstrates a low-cost solution
for satellite radio apparatuses based on commercial components
on a standard PCB
INFN What Next: Ultra-relativistic Heavy-Ion Collisions
This document was prepared by the community that is active in Italy, within
INFN (Istituto Nazionale di Fisica Nucleare), in the field of
ultra-relativistic heavy-ion collisions. The experimental study of the phase
diagram of strongly-interacting matter and of the Quark-Gluon Plasma (QGP)
deconfined state will proceed, in the next 10-15 years, along two directions:
the high-energy regime at RHIC and at the LHC, and the low-energy regime at
FAIR, NICA, SPS and RHIC. The Italian community is strongly involved in the
present and future programme of the ALICE experiment, the upgrade of which will
open, in the 2020s, a new phase of high-precision characterisation of the QGP
properties at the LHC. As a complement of this main activity, there is a
growing interest in a possible future experiment at the SPS, which would target
the search for the onset of deconfinement using dimuon measurements. On a
longer timescale, the community looks with interest at the ongoing studies and
discussions on a possible fixed-target programme using the LHC ion beams and on
the Future Circular Collider.Comment: 99 pages, 56 figure
Charge separation relative to the reaction plane in Pb-Pb collisions at TeV
Measurements of charge dependent azimuthal correlations with the ALICE
detector at the LHC are reported for Pb-Pb collisions at TeV. Two- and three-particle charge-dependent azimuthal correlations in
the pseudo-rapidity range are presented as a function of the
collision centrality, particle separation in pseudo-rapidity, and transverse
momentum. A clear signal compatible with a charge-dependent separation relative
to the reaction plane is observed, which shows little or no collision energy
dependence when compared to measurements at RHIC energies. This provides a new
insight for understanding the nature of the charge dependent azimuthal
correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286
Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at = 5.02 TeV
Two-particle angular correlations between unidentified charged trigger and
associated particles are measured by the ALICE detector in p-Pb collisions at a
nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum
range 0.7 5.0 GeV/ is examined,
to include correlations induced by jets originating from low
momen\-tum-transfer scatterings (minijets). The correlations expressed as
associated yield per trigger particle are obtained in the pseudorapidity range
. The near-side long-range pseudorapidity correlations observed in
high-multiplicity p-Pb collisions are subtracted from both near-side
short-range and away-side correlations in order to remove the non-jet-like
components. The yields in the jet-like peaks are found to be invariant with
event multiplicity with the exception of events with low multiplicity. This
invariance is consistent with the particles being produced via the incoherent
fragmentation of multiple parton--parton scatterings, while the yield related
to the previously observed ridge structures is not jet-related. The number of
uncorrelated sources of particle production is found to increase linearly with
multiplicity, suggesting no saturation of the number of multi-parton
interactions even in the highest multiplicity p-Pb collisions. Further, the
number scales in the intermediate multiplicity region with the number of binary
nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/161
A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE
In this small note we are concerned with the solution of Forward-Backward
Stochastic Differential Equations (FBSDE) with drivers that grow quadratically
in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem
is a comparison result that allows comparing componentwise the signs of the
control processes of two different qgFBSDE. As a byproduct one obtains
conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio
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