1,721,409 research outputs found
DESIGN FOR ROBUSTNESS OF A PILOT BUILDING EQUIPPED WITH DISSIPATIVE FREE FROM DAMAGE STEEL CONNECTIONS
No full textRecent research initiative aimed at reducing the structural damage and its inherent economic consequences in steel and steel-concrete composite structures after severe earthquakes led to the development of FREE from DAMage (FREEDAM) beam-to-column connections. The practical applicability and the benefits of using these connections for structures in seismic areas are currently demonstrated within an ongoing RFCS pilot project to be built on the campus of the University of Salerno. Amongst the different structural requirements, Euro-codes nowadays require providing the structures with an appropriate robustness when subjected to identified or unidentified accidental events by ensuring that the undergone damages are not disproportionate to the initiating cause. This paper presents the design for robustness of the pilot building. The results indicate that the loss of a column at the base floor induces the development of significant catenary action in the beams bridging over the lost column. The structural performance under the column loss scenario is primarily governed by the behaviour of beam-to-column joints subsequently identified as critical zones. The full-range behaviour of the FREEDAM joints was investigated through complex numerical simulations which allowed validating a simplified component-based spring model that can be adopted for the regular design of structures adopting this joint typology
The pure sliding collapse mode of non-symmetric masonry arches: a critical review of Monasterio's contribution and an alternative formulation
Full text linkAim of the present paper is to analyze and revisit the first chapter of the Monasterio’s unpublished manuscript where the pure sliding collapse mode of non-symmetric masonry arches is investigated. As it will be shown, the Monasterio approach is of a “kinematical” type, since the collapse mechanisms are “a priori” selected and, then, some criterion is adopted to identify the collapse condition. In the present study, it will be shown that the basic assumptions of the Monasterio’s analysis are fully in agreement with the modern limit analysis. Furthermore, an alternative formulation for the assessment of the equilibrium of non-symmetric arches is given
Kinematic Stress Resultants in Inclined Single Piles Subjected to Propagating Seismic Waves: an Analytical Formulation
No full textThis paper presents an analytical model, based on the beam-on-dynamic Winkler foundation approach, for the evaluation of the kinematic stress resultants in single inclined piles subjected to the propagation of seismic waves. The Euler-Bernoulli beam model is adopted for the pile whereas analytical solutions available in literature for viscoelastic layers undergoing harmonic vibrations of a rigid disk are used for the soil. The coupled flexural and axial behaviour of the pile is governed by a system of partial differential equations, with the relevant boundary condi-tions, that is solved analytically in terms of exponential matrices. The solution for piles embed-ded in a homogeneous soil deposit is presented. Some applications, including comparisons of results with those obtained from rigorous boundary element formulations, demonstrate that the model, characterised by a very low computational effort, is able to accurately predict stress re-sultants in inclined piles subjected to seismic loading
Struct-Stainability assessment of the Columna Capreoli A-Trusses of the San Lorenzo ad septimum monastery aula magna
No full textOriginal methodologies are proposed for formulating and solving optimization design problems concerned with the hazard assessment of a hypothetical solid wood replacement of the restored columna-capreoli A-trusses of the Aula Magna “Alfonso Gambardella” of the ancient monastery complex of San Lorenzo ad Septimum in Aversa, currently hosting the Department of Architecture and Industrial Design of the University of Campania “Luigi Vanvitelli”. The study addresses a twofold struct-stainability performance evaluation contemplating both the structural hazard originated from natural combined gravitational and dynamic actions, and the demand related to dynamics of anthropic/anthropogenic ecosystem consumption/transformation, in a scenario of short wood supply chain within the Piana Campana area. Both the contemplated hazard scenarios appear meaningful since: 1) the complex has suffered significant earthquake damage between 1456-1457, and 2) dedicated environmental studies by ISPRA/ARPAC elucidate a worrying condition of very high fragility for most of the lake, river and coastal ecosystems of the Piana Campana as well as an ‘endemic’ fragility condition for most of its territory. Encompassing both hazard perspectives, the optimization problems considered herein address the optimal choice between open- and closed-node solutions for the kingpost-strut A-trusses of the installation. Performance analyses have been carried out with the aid of an object-oriented in-house-developed multipurpose structural analysis code (MORES), employing finite-element formulations with a transversely isotropic structural model for wood based on a polytope strength criterion which has been calibrated from data made available from the military aeronautic industry and which has been suitably experimentally and numerically validated
RETROSPECTIVE OPERATIONAL AFTERSHOCK FORECASTING FOR 2016 AMATRICE-NORCIA SEISMIC SEQUENCE IN CENTRAL ITALY
No full textThe first days elapsed after the occurrence of an earthquake and its triggered aftershocks are crucial in terms of emergency decision-making. To this end, the adopted novel and fully-probabilistic procedure succeeds in providing spatio-temporal predictions of aftershock oc-currence in a prescribed forecasting time interval (in the order of hours or days). The proce-dure aims at exploiting the information provided by the ongoing seismic sequence in quasi-real time. The versatility of the Bayesian inference is exploited to adaptively update the fore-casts based on the incoming information as it becomes available. The aftershock clustering in space and time is modelled based on an Epidemic Type Aftershock Sequence (ETAS) model. One of the main novelties of the proposed procedure is that it considers the uncertainties in the aftershock occurrence model and its model parameters. This is done by pairing up the Bayesian robust reliability framework and the suitable simulation schemes (Markov Chain Monte Carlo Simulation) provides the possibility of performing the whole forecasting proce-dure with minimum (or no) need of human interference. This procedure is demonstrated through a retrospective spatio-temporal early forecasting of seismicity associated with the 2016 Amatrice-Norcia seismic sequence in central Italy. Seismicity forecasts are issued with various time intervals in the first few days after the main events within the sequence
Seismic assessment of existing Italian RC precast structures
No full textThe paper presents a comprehensive seismic assessment of an existing single-story reinforced
concrete (RC) precast structure, resembling the typical characteristics of Italian industrial
facilities. For a more realistic evaluation, a simulated design is performed, accounting for old
codes and seismic zonation. Then, state-of-the-art nonlinear models are developed in Open-
Sees, considering or not the contribution of lateral cladding, made by masonry infills. Nonlinear
dynamic analyses are performed, achieving a wide and accurate seismic assessment.
Obtained outcomes highlights the main vulnerabilities of existing precast buildings in Italy,
providing useful insights on their seismic behavior. Lastly, failure rates are evaluated and
presented
Ambient vibration test on an existing prestressed concrete bridge
No full textThe dynamic test in situ of existing bridges is a very promising solution for assessing a reliable model, since it is more convenient than a load test requiring to organize the trucks and close the use of the infrastructure for a longer time. However its effectiveness depends on the test technique, the number, type and location of the sensors, but also on the numerical model that have to allow the introduction of the real boundary conditions. Cleary the dynamic identification of the structural behavior can be also the first step of a monitoring process to check the health of the construction during the time, therefore its effectiveness is fundamental. In this paper the first results of the structural identification based on an ambient vibration test of an existing prestressed concrete bridge are presented. The selected case study is a bridge designed by Riccardo Morandi in 1952-1955 with the emerging technique of Prestressed Concrete (PC). An important step of the process is the developing of the model though a survey and a wide investigation campaign, but also the role of the knowledge of the original design is highlighted due the complexity of the structure
Seismic assessment of a RC case study building using the Simple Lateral Mechanism Analysis, SLaMA, method
No full textThe seismic assessment of an existing structure is a complex procedure. In
the
eval-
uation
of
the structural capacity
,
difficulties arise in the definition of the lateral resisting mem-
bers,
in
the estimation of
the
lateral capacity
from component
to
system level
.
T
he
identification
of the local and global mechanism
s
,
depending on the
hierarchy of strength
at subassembly
level, is
a
challenging
task
. Nowadays,
advanced
numerical
analys
i
s
procedures
, implemented
in user
-
friendly commercial software, are commonly adopted in the current practice to over-
come the difficulties in the use of non
-
linear
analyses
.
Ne
vertheless, their accuracy strongly
depends on the ability of the numerical model to capture all the probable failure mechanisms.
To help the user
in the assessment of the probable failure mechanism and to have a first esti-
mation of the building lateral ca
pacity,
the Simple Lateral Mechanism Analysis (SLaMA)
method
has been recently developed and included in the
NZSEE
2016
guidelines. SLaMA is a
simple
and reliable
“by
-
hand”
tool to derive the local and global mechanism of a structural
system and the corresponding capacity curve.
T
his paper
deals with the application of the
SLaMA to
an existing
RC
building severely damaged during the Christchurch earthquake (2011
,
New Zealand
)
.
The lateral capacity of f
our 2D resisting systems
was
assessed following the
SLaMA
method
.
The
results of a refined nonlinear numerical model were used to assess the
accuracy and reliability of
SLaMA.
The good match confirmed that SLaMA can be a useful
and simple
tool to have a first estimation of the building lateral response
. It allows to identify
the main structural weaknesses driving the user to the development of
more refined nonlinear
model
- …
