327 research outputs found
Shear panel for seismic protection of structure
No full textThe paper describes a new dissipation device that can be used to preserve the structural integrity of civil engineering structures under seismic loads. The proposed device is made in aluminum and dissipates energy through the hysteretic behavior and the local plasticization. It is a very simple device with a low cost of production. The proposed dissipator has been tested using a monotonic type of experiment in order to define its main characteristics, then its dynamic characteristic behavior has been obtained through some tests on a 3D shaking table. The frame has been subjected to a series of accelerograms allowing to determine the dynamic behavior of the shear panels under severe work conditions, and to assess the efficiency of the device
Non-destructive techniques and monitoring for the evolutive damage detection of an ancient masonry structure
No full textIn the present article non-destructive testing evaluation of the existing damage evolution
has been applied to some buildings of the medieval town of Craco (Matera, Italy) and, in particular,
to the Normand tower. Actually the little town of Craco is totally abandoned as a consequence of
the activation of the landslide motions of its soil depth. Nevertheless, the Normand tower still
stands because it is located on a stable and stiffer foundation ground.
The tower was built in the XII century. It is 20 m tall and has a symmetric square plan, with
dimensions 11 m x 11 m; it was built for defense against enemy attacks.
Inside the tower a cistern in reinforced concrete was placed in 1949. It is not connected to the
structural walls of the tower; however it represents an obstacle for installing the damage detection
equipment and sensors.
In this article a preliminary study on the masonry structure of the Normand tower is carried on.
A finite element numerical model has been developed and a modal analysis has been performed.
The final aim of the research is to find out the evolutionary stage of the cracks and to propose a
possible retrofit of the tower
On the Seismic Response of Protected and Unprotected Middle-Rise Steel Frames in Far-Field and Near-Field Areas
No full textSeveral steel moment-resisting framed buildings were seriously damaged during Northridge (1994); Kobe (1995); Kocaeli, Turkey (1999), earthquakes. Indeed, for all these cases, the earthquake source was located under the urban area and most victims were in near-field areas. In fact near-field ground motions show velocity and displacement peaks higher than far-field ones. Therefore, the importance of considering near-field ground motion effects in the seismic design of structures is clear. This study analyzes the seismic response of five-story steel moment-resisting frames subjected to Loma Prieta (1989) earthquake—Gilroy (far-field) register and Santa Cruz (near-field) register. The design of the frames verifies all the resistance and stability Eurocodes’ requirements and the first mode has been determined from previous shaking-table tests. In the frames two diagonal braces are installed in different positions. Therefore, ten cases with different periods are considered. Also, friction dampers are installed in substitution of the braces. The behaviour of the braced models under the far-field and the near-field records is analysed. The responses of the aforementioned frames equipped with friction dampers and subjected to the same ground motions are discussed. The maximum response of the examined model structures with and without passive dampers is analysed in terms of damage indices, acceleration amplification, base shear, and interstory drifts
Preliminary analysis of concrete reinforced with waste bottles PET fibers
No full textAs part of the research on fiber-reinforced concrete, the results of some tests for an approach to a broader
testing on the possibility of using fibers from polyethylene terephthalate (PET) bottles to increase the
ductility of the concrete are reported. The fibers are simply cut from waste plastic bottles reducing, in this
way, the manufacturing costs of recycled PET fiber-reinforced concrete. The aim of this paper is to explore
the possibility of re-cycling a waste material that is now produced in large quantities, while achieving an
improvement of the ductility of the concrete
Identification of the Modal Properties of a Building of the Greek Heritage
No full textIn this paper, the experimental modal identification analysis of the public building “San
Giacomo” in Corfu (Greece) is illustrated. It represents the unique example of a structure built
utilising carves stones inside the city of Corfu. The building has a rectangular plan shape with
dimensions 24.75 x 14 m, and height 9 m; all the floors are made by wood. The monitoring system
consists of several elements properly connected: the units of acquisitions or piezoelectric
accelerometers (in total 18 installed on the different walls) with a sensitivity of 1000 mV/g; the data
acquisition system or DAQs positioned at each monitored level; the laptop with an acquisition
software; the cables that connect all elements to each other.
The paper describes the phases of the investigations, the technical details of the performed in-situ
tests, the first identified frequencies of the building by means of the classical methods of
Operational Modal Analysis (OMA) and the comments about the acquired data
Response of frames seismically protected with passive systems in near-field areas
No full textThe present paper analyses the behaviour of moment resisting
frames in reinforced concrete subject to earthquakes recorded in near-field
areas. In these areas, the signals show impulsive-type accelerograms, with
velocity and displacement peaks higher than in far-field zones especially for the
fault-normal component of the ground motion velocity in the direction of
propagation of the wave, which shows large-amplitude pulses. In the following,
seven near-field signals scaled in agreement with the design spectrum of the
Italian code (NTC, 2008) have been adopted to perform a nonlinear analysis on
a six-story frame. The response has also been determined for the same frame
protected once with hysteretic-type energy dissipaters and once with base
isolators. The aim of the present study is to acquire quantitative knowledge on
the near-field ground motion effects on frame buildings and on their damage
also in the presence of passive seismic protection system
On the Numerical and Experimental Strengthening Assessment of Tufa Masonry with FRP
No full textIn this paper a constitutive relation of bounded tensile strength function of the strain state of the material is proposed for tufa masonry structures with and without Fiber Reinforced Polymer (FRP) reinforcement. The fiber-reinforcement is modeled as a linear elastic material with no-compression strength. Tests have been performed to verify the proposed model and the efficacy of this structural FRP reinforcement technique for masonry.
Tests have utilized brick specimens, little beam specimens and masonry panels. Results demonstrated the effectiveness of the strengthening technique and the capacity of the constitutive equation to model the behavior of more complex fiber-reinforced masonry structures
Structural Monitoring of Artistic and Historical Building Testimonies
No full textS.M.ART. BUIL.T. “Structural Monitoring of ARTistic and historical BUILding Testimonies” is a project
founded by the European Territorial Cooperation Programme Greece-Italy 2007/2013 and leaded by the
Polytechnic of Bari. The core idea of “S.M.ART. BUIL.T.” is risks prevention, which concerns not only the
prevention of loss of lives and properties, but also the preservation of artistic and historical buildings from
natural hazards.
Architectural heritage is an important part of the history and identity of Italy and Greece, contributing to
their economy and well being. On the other side, ancient buildings suffer a high vulnerability to dynamic
loads, which may induce an unpredictable partial or total collapse. Recent past experience after L’Aquila
earthquake strongly evidence this problem.
The main objectives of the international project “S.M.ART.BUIL.T.” are the implementation of procedures
for the structural monitoring, the seismic vulnerability assessment, the development of guidelines for
strengthening and repair of the historical buildings (in Trani and Corfu). The project aims at providing to
technical officials of the territorial authorities of Puglia and Ionian Islands Regions some indispensable
training tools for the development and/or validation of structural restoration projects and seismic
rehabilitation of historical buildings. Most of buildings of artistic value, in the two historic centers, are
invariably built of masonry, a material as old as the civilization and with a 10,000 years record of success
and lasting qualities, representative of a widespread typology in the Mediterranean area.
The final step has been the International Conference titled “HISTORICAL CENTRES AMONG CULTURE, ART
AND TECHNIQUES: A NEW PARADIGMA FOR RISKS PREVENTION THROUGH STRUCTURAL MONITORING”,
which also represents the most important action of diffusion activities of the S.M.ART.BUIL.T. project.
The Final Conference has been open to all experts in the following topics: seismic and structural
monitoring, historical and artistic heritage, computational and technological issues applied to historical
heritage, in order to exchange experience of correlated research areas. The main purpose has been to
make the conference a forum for dissemination of the latest scientific and technical developments and for
exchange of new ideas in emerging topics of the project.
The main conference topics has been divided into three areas and chapters, following the three main souls
of the project:
1. HISTORICAL AND ARTISTIC AREA
2. STRUCTURAL AREA
3. COMPUTATIONAL AND TECHNOLOGICAL ARE
Risposta di telai protetti con dissipatori di energia da terremoti in zone prossime alle faglie
No full textOn the Optimum Placement of Dissipators in a Steel Model Building Subjected to Shaking-Table Tests
No full textThe following research presents the numerical and experimental results obtained on a reduced scale steel model
of a medium-rise building structure dynamically protected with energy dissipaters. The steel-steel friction dissipates energy
as the structure undergoes interstory drifts. A preliminary numerical analysis is performed to determine the best position
of the friction dampers in the longitudinal frames. All the nodes of the numerical model have been assumed with the
same bending stiffness. Shaking table tests have been performed, both in random vibration tests (to determine the natural
periods and the dynamic characteristics of the model) and in earthquake simulation tests (to study the dynamic behaviour
of the model with and without dampers). The results have been compared to those achieved during a previous experimental
study based on the same model protected with only one friction damper for each longitudinal frame
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