The research group works, since many years, in the field of
the earthqauke engineering, with specific reference to new
methodologies for the seismic design of civil structures, and of the bridge enegineering. In
detail, the research topics are the followings ones:
1. Use of viscous dampers for the mitigation of the seismic action upon structures.
2. Torsional phenomena in building structures characterized by eccentricity in plan between the centre of mass and the centre of stiffness.
3. Development of “Crescent-Shaped Braces” capable of satisfying multiple seismic design objectives in the Performance-Based Seismic Design framework (analytical and numerical studies, quasi-static experimental tests).
4. Seismic response of silos: analytical developments and design, carrying out and interpretation of experimental shaking table tests ("SEismic Response of Actual steel SILOS ‐ SERA‐SILOS" European Project, SERA call, 2018-2019).
5. Experimental research, analytical developments and analytical/experimental correlation study on the cyclic behaviour of structures composed of lightly reinforced concrete walls.
6. Probabilistic and deterministic seismic hazard analyses (analytical and numerical studies).
7. Methodologies for the probabilistic identification of reference design earthquake inputs for non-linear dynamic analyses in the Performance Based Seismic Design framework (analytical and numerical studies).
8. Design, carrying out and interpretation of experimental shaking table tests on a 3-storey full-scale building, realized with a structural system composed of squat r.c. sandwich panels at the EUCENTRE lab of Pavia (SERIES project, European FP7 program).
9. Assessment of the structural safety, seismic analyses and interpretation of the monitoring data of historical monumental buildings, with specific reference to the Cathedral of Modena and the 2 Towers of Bologna.
10. Pseudo-static and shaking-table experimental tests on scaled cross-vault models as subjected to in-plane shear deformation ("SEeismic BEhavior of Scaled MOdels of groin VAults made by 3D printers - SEBESMOVA3D" European Project, SERA call, 2018-2019).
11. Earthquake-resistant constructions in developing countries: study of the seismic behavior of gabion-box wall buildings, "bhatar" buildings and rubble-stone masonry buildings.
12. Structural monitoring of historic monumental buildings and existing bridges.
13. Structural assessment of bridges, with particular reference to the monitoring of prestressed reinforced concrete bridges and the definition of mechanical models for the estimation of the residual strength of corroded strands.
DETAILED DESCRIPTION
1. Use of viscous dampers for the mitigation of the seismic
action upon structures.
TOPIC: Dissipative systems have widely proven to be able to
effectively mitigate seismic effects on buildings. However, still
the issue is open of how to insert viscous dampers into shear-type
structure in order to reach the best dissipative performances of
the dynamic system (structure + dampers). In fact, most of the
research works available in literature regarding the problem of
damper system optimisation deals with the search for optimal damper
sizing for given traditional inter-storey damper placement.
CONTRIBUTION: Analytical identification of the superior
dissipative properties of the so-called MPD (Mass Proportional
Damping) systems as applied to shear type frame structures.
Development of strategies for their implementation in actual
building structures. Development of a simple original procedure for
the identification of the mechanical characteristics of the
manufactured viscous dampers which allow to achieve target levels
of performances. Identification of the force reduction factors to
be used for highly damped structures, for the intermingling of the
inexpensiveness due to the ductility capacities of the structural
elements and the efficiency due to the added viscous dampers.
2. Torsional phenomena in building structures characterized by
eccentricity in plan between the centre of mass and the centre of
stiffness.
TOPIC: Structures characterized by non coincident centre of
mass and centre of stiffness (eccentric structures) when subjected
to dynamic excitation, develop a coupled lateral-torsional response
that may increase the local peak dynamic response. This behaviour
has been investigated by many researchers since the late 1970s.
Nevertheless a number of issues still remain unresolved in the
areas of inelastic response and development of simplified, yet
physically-based design procedures. In particular, in order to
effectively apply the performance-based design approach to seismic
design, there is a growing need for code oriented methodologies
aimed at predicting deformation parameter.
CONTRIBUTION: Development of predictive formulas for the
estimation of the increment of the displacement demand in such
eccentric structures (with respect to the corresponding
non-eccentric structures). These formulas make use of simple
synthetic parameters based upon the static characteristics of the
systems. The effectiveness of the proposed formulation has been
verified both numerically and experimentally, these last through
shaking table tests.
3. Development of “Crescent-Shaped Braces” capable of satisfying multiple seismic design objectives in the Performance-Based Seismic Design framework (analytical and numerical studies, quasi-static experimental tests).
4. Seismic response of silos.
TOPIC: In the general issues concerning the actions provoked
by earthquake ground motion on the walls of flat-bottom grain
silos, the assessment of the horizontal actions seems to be of
particular interest. These actions are usually evaluated under the
following hypotheses: (i) stiff behaviour of the silo and its
contents (which means considering the silo and its contents to be
subjected to ground accelerations); and (ii) the grain mass
corresponding to the whole content of the silo except the base cone
with an inclination equal to the internal friction angle of the
grain is balanced by the horizontal actions provided by the walls
(supposing that the seismic force coming from the base cone is
balanced by friction and therefore does not push against the
walls). This design approach is not supported by specific
scientific studies; as a matter of fact, even though there are many
papers on the behaviour of liquid silos under earthquake ground
motion, there are no examples of scientific investigation into the
dynamic behaviour, let alone under earthquake ground motion, of
flat-bottom grain silos.
CONTRIBUTION: Development of predictive formulas for the
estimation of the horizontal actions exerted by grain-like
materials upon the walls of flat-bottom squat silos during
earthquake. These analytical formulas (based on the assumptions
made by Janssen and Koenen for their “static” analyses) are
currently the object of specific shaking table tests at the
Earthquake Centre of Bristol (European SERIES project). The
experimental results obtained so far confirm the effectiveness of
the proposed formulation in better capturing the actual seismic
actions on the silo walls with respect to the Eurocode 8
prescriptions.
5. Experimental research, analytical developments and
analytical/experimental correlation study on the cyclic behaviour
of structures composed of lightly reinforced concrete walls.
TOPIC: Buildings made up of reinforced-concrete walls
represent a structural typology which has been widely used in
economic public housing. In these structures, the walls are often
characterised by small thickness (15 - 25 cm) and by small
percentage values of steel reinforcement. These buildings have
shown excellent strength resources even against strong earthquake
ground motions: the structural overstrength allows to reduce the
ductility demand. However, still few experimental and analytical
studies have been performed up to now with the aim of evaluating
the ultimate (near-collapse) seismic performances of buildings
realised using large lightly-reinforced concrete walls.
CONTRIBUTION: The research group has recently organised,
designed and interpreted (by means of appropriately-developed
analytical models capable of capturing the experimental behaviour)
a series of experimental tests with cyclic horizontal loading
(conducted at the laboratory of the European Seismic Centre
EUCENTRE in Pavia) upon a peculiar typology (with nonreturnable
block-formwork) of lightly reinforced concrete walls. The
construction process of such structures sees the realisation of
bearing walls through the casting of ordinary concrete inside
wood-cement block-formworks. Due to the peculiar conformation of
the block-formwork, the structural wall so-obtained is
characterised by the presence of lightening alveolar zones. Inside
the blocks, before casting the concrete, appropriate horizontal and
vertical reinforcement steel bars are placed, so that the
structural walls is actually a reinforced-concrete wall. To obtain
an adequate characterisation of the seismic behaviour (stiffness,
strength, ductility) of such walls, experimental pseudo-static
tests with constant vertical loading and increasing horizontal
loading have been carried out both upon single walls and upon a
H-shaped 2-storey structural system. The results obtained show a
good ductile behaviour, yielding horizontal loads comparable with
applied vertical loads, and the maintenance of strength to vertical
loads after damaging. Degradation of material is substantially
acceptable.
6. Probabilistic and deterministic seismic hazard analyses
(analytical and numerical studies).
TOPIC: In a Performance Based Seismic Design framework, it is
of fundamental importance the determination of the “demand” imposed
upon the structure by the seismic action. Structural demand is
generally evaluated through series of non linear dynamic analyses
(Probabilistic Seismic Demand Analysis) obtained using as inputs
selected (typically historically) seismic records which are
correlated to specific hazard levels. A key step in the whole
procedure is represented by the correct probabilistic evaluation
(on the basis of Probabilistic Seismic Hazard Analysis) of the
reference (design) acceleration time histories. For each design
level (the typical PBSD procedure is articulated in 4 design levels
corresponding to a probability of 50%, 30%, 10% and 2% of
occurrence upon the life span of the structure), it is thus
necessary to identify a group of reference inputs (often referred
to as “bin”). Bins are typically identified on the basis of a set
of ground motion parameters referred to as Intensity Measures (IM),
both scalar or vectorial.
CONTRIBUTION: The research group has developed two procedures
for the Probabilistic Seismic Hazard Analysis (PSHA). The
probability functions (PDF and CDF) of a selected ground motion
parameter (e.g., peak ground acceleration, peak ground velocity,
peak ground displacement, spectral acceleration, …) at a specific
site, over a given observation time, are analytically developed and
elucidated. Both procedures are developed according to Cornell's
widely upheld approach (1968). The first procedure is characterized
by the treatment of the distance R from the epicentre to the site
as a continuous random variable, while the other treats R as a
discrete variable. Both procedures lead to closed-form analytical
expressions for the PDF and CDF of the selected ground motion
parameter. Grounded on the results of the developed PSHA, a
vectorial Intensity Measure has been proposed as composed by the
PGA and the PGV. Non-linear time-history dynamic analyses carried
out using, as earthquake input, groups of seismic records obtained
on the basis of couples PGA-PGV have shown to lead to results
characterised by smaller dispersion with respect to the results
obtained through analyses carried out using, as earthquake input,
groups of seismic records obtained on the basis of other suggested
Intensity Measures.
7. Methodologies for the probabilistic identification of
reference design earthquake inputs for non-linear dynamic analyses
in a Performance Based Seismic Design framework (analytical and
numerical studies).
8. Design, carrying out and interpretation of experimental
shaking table tests on a 3-storey full-scale building, realized
with a structural system composed of squat r.c. sandwich panels at
the EUCENTRE lab of Pavia (SERIES project, European FP7
program).
9. Assessment of the structural safety, seismic analyses and
interpretation of the monitoring data of historical monumental
buildings, with specific reference to the Cathedral of Modena and
the 2 Towers of Bologna.am).
10. Pseudo-static and shaking-table experimental tests on scaled cross-vault models as subjected to in-plane shear deformation ("SEeismic BEhavior of Scaled MOdels of groin VAults made by 3D printers - SEBESMOVA3D" European Project, SERA call, 2018-2019).
11. Earthquake-resistant constructions in developing countries: study of the seismic behavior of gabion-box wall buildings, "bhatar" buildings and rubble-stone masonry buildings.
12. Structural monitoring of historic monumental buildings and existing bridges.
13. Structural assessment of bridges, with particular reference to the monitoring of prestressed reinforced concrete bridges and the definition of mechanical models for the estimation of the residual strength of corroded strands.
