1,720,975 research outputs found
U.l.S. 3D domain of rectangular cross-sections in r.c. subject to shear and torsion
No full textThis paper aims to illustrate a unified approach for the process of the Ultimate Limit State (ULS) design
and check of rectangular sections in reinforced concrete (r.c.) subject to composed forces of shear and torsion.
This approach was developed by the authors starting from established theoretical hypotheses and
categorizations and from the resulting equations; it can solve the shear-torsion problem in a unified
and organic way considering a single 3D resistance domain obtained from assembling three distinct
2D graphics actually utilized in the current procedure. The 3D domain has the high advantage to propose
a more comprehensive approach to the problem and more careful and precise results
An energy router for structural monitoring of framed buildings and real-time shutdown of power and gas supply during earthquakes
No full textThe paper proposes the integration of structural monitoring with Building Management Systems for electricity and gas distributions. To assess the state of damage of existing buildings the technics of Structural Health Monitoring (SHM) is adopted. SHM as well as to record the occurrence of sudden structural damage resulting from exceptional events (earthquakes, explosions, shocks and collisions with vehicles, etc.), allows the monitoring of the progressive damage and structural performance under operating conditions through the extraction of the modal parameters of the structure. This approach requires time to process acquired data that, depending on the size of the building and the number of monitored points, varies from minutes to hours. In this paper, an intelligent system is proposed to immediately communicate during an earthquake the overrun of a certain ground shaking threshold so that gas delivery and selected power loads are interrupted, as suggested by current national regulations on structures. The use of low-cost and reduced size accelerometric sensors integrated with Energy Monitoring Systems is proposed in both high-risk earthquake centers and in all “strategic” buildings that must ensure their operation immediately after the earthquake. The procedure for calibrating the horizontal and vertical acceleration threshold is also presented. It is also explicitly required by the existing structural and seismic codes in which electricity and gas distribution systems must be fitted with valves for automatic earthquake disconnection. The present work is also embedded in a long-established research that seeks the obligation for designers to analyze not only the structural aspect of the building, but also all the non-structural elements, including Plant elements
Bell's dynamic interaction on a reinforced concrete bell tower
No full textThe present study shows a cheap and simple methodology to evaluate the dynamic behavior of a reinforced concrete bell tower built in 1974 made of concrete structural elements and brick masonry walls. The bell swinging vibrations on the tower are evident and they can be visually observed even without the use of any equipment. In this case a possible interaction between the bells’ swinging and the tower vibration has been dynamically identified by the methodology here proposed. An experimental campaign was carried out on the bell tower to record the environmental vibrations and the accelerations induced by the movement of the bells during their swinging. In order to develop the methodology here proposed, the main characteristics of the bells have been measured and the time history force generated by each bell during the swing has been evaluated. A numerical model of the tower has been developed and calibrated by the Operational Modal Analysis technique. The model has then been validated utilizing the acceleration time-histories recorded under forced excitations. Dynamic analyses have been carried out on the bell tower and the dynamic amplification factor (DAF) has been determined. From the results it is noticed that the bell tower does not comply with its maximum capacity due to the dynamic interaction with the bells swinging as evidenced by the presence of cracks on the facades of the tower. This paper highlights the dynamic problems that bells can cause to slender bell towers and proposes a simple and cheap solution
Evaluation of building seismic retrofitting costs foundedon experimental data. The case study of "San Benedetto" School (Norcia, Italy)
No full textEvaluation of seismic retrofitting costs, a key issue in the risk mitigation strategies, requires the estimation of the building performance and the forecast of the site response. In addition, a target building performance should be a priori defined. In this study, a procedure to provide seismic retrofitting costs is suggested with reference to a case study, based on what following: i) the building performance is described by fragility curves obtain via recorded data on the building itself (Seismic Model from Ambient Vibration - SMAV), ii) the local seismic site response is estimated by means of numerical one-dimensional simulation based on site-specific data or by means of simplified technical code approach, iii) the building performance and the site response are combined in order to obtained an Annual Frequency of Failure for each damage limit state, iv) this frequency is compared to the target allowable reliability level according to the classes of use and limit states of building in order to obtained a Vulnerability index, v) seismic retrofitting costs, depending on the Vulnerability index values, are evaluated from literature suggestions (Cat erino et alii, 2018). Finally, with reference to the case study of the "San Benedetto" school of Norcia (Central Italy), the proposed methodology is satisfactorily verified by comparing the forecast with real costs. The innovative aspect of the proposed methodology lies in the use of the recorded data and SMAV model and in the procedure for defining the local seismic response which considers the building-specific characteristics and the site-specific conditions
Experimental Characterization of Traditional Mortars and Polyurethane Foams in Masonry Wall
Full text linkMasonry is a composite material largely used in construction. It exhibits several advantages, including significant compressive strength, thermal inertia, and aesthetic beauty. A disadvantage of masonry is mainly related to the inadequate shear strength due to the poor capacity and ductility of the adopted mortar. This aspect is crucial in seismic areas. In this paper, the behavior of polyurethane foams, used as adhesives for the construction of thin joints brick masonry walls, has been investigated. First, the characterization of components was carried out, followed by laboratory uniaxial tests on masonry walls and shear tests on triplets. Moreover, a comparison of the behavior of the foam-brick walls with respect to the traditional mortars masonry was carried out, as the type of joints varies and the arrangement of the holes of the bricks varies with respect to the direction of the applied load. Results provide indications on which adhesive has to be adopted for masonry buildings in reference to the site of construction (i.e., seismic hazard)
EXPERIMENTAL INVESTIGATION OF THE SEISMIC RESPONSE OF A MULTI-DRUM COLUMN
No full textIn this paper, the experimental results of a multiblock column have been demonstrated by the harmonic
and cyclic impulse movements of the base. The tests were performed on a shaking-table with one degree
of freedom at the Materials Testing Laboratory “M. Salvati” of the Polytechnic University of Bari for
the rigid and deformable foundation column. Through the use of 3D printing, a staircase prototype of
6 blocks along the stem plus the capstone was built, with a base-diameter ratio of 6.5. Geometric
features represent a “standard” column belonging to the classical Doric order in the Mediterranean
basin. The main aim of this paper was to study the influence of deformability of the foundation on the
overall dynamics of the phenomenon in order to address operational solutions that reduce the seismic
vulnerability of such structures that are technically and technologically compatible with the current
archaeological cultur
Control of framed structures using intelligent monitoring networks
Full text linkThe paper proposes the integration of structural monitoring with Building Management Systems for electricity and gas distributions. To assess the state of damage of existing buildings the technics of Structural Health Monitoring (SHM) is adopted. SHM as well as to record the occurrence of sudden structural damage resulting from exceptional events (earthquakes, explosions, shocks and collisions with vehicles, etc.), allows the monitoring of the progressive damage and structural performance under operating conditions through the extraction of the modal parameters of the structure. This approach requires time to process acquired data that, depending on the size of the building and the number of monitored points, varies from minutes to hours. In this paper, an intelligent system is proposed to immediately communicate during an earthquake the overrun of a certain ground shaking threshold so that gas delivery and selected power loads are interrupted, as suggested by current national regulations on structures. The use of low-cost and reduced size accelerometric sensors integrated with Energy Monitoring Systems is proposed in both highrisk earthquake centers and in all “strategic” buildings that must ensure their operation use immediately after the earthquake. The procedure for calibrating the horizontal and vertical acceleration threshold is also sketched
Dynamic Monitoring and Identification of a New Italian Cable-Stayed Bridge During Dynamic Load Tests
No full textThe new cable-stayed bridge built for the North-South axis road of Bari in order to overpass the
railway of RFI and Ferrotramviaria s.p.a. has been recently built and opened to the traffic. The bridge
is 626 m long and the central cable-stayed bays have a total length of 225 m. They are supported by
30 cables connected to a central upside down Y-shaped pylon. The peculiarity is that this column is
about 60° rotated with respect to the axis of the bridge deck. Just a couple of weeks before its opening
the last dynamic check has been designed and performed by the authors with the aim to identify the
first frequencies and modes. 26 piezoelectric accelerometers have been utilized in different positions
of the cables-stayed bays to record the accelerations produced by environmental forces and by the
impact produced by a loaded truck of about 38 tons passing over a bump. Operational Modal Analysis
has been applied by mean of Artemis software to determine the first fundamental frequencies, the
mode shapes and damping factors
Structural defects for condition assessment of existing bridges: some results of a territorial case study
No full textRecent events involving the tragic collapse of existing bridges have led to an increasingly detailed study of infrastructure and its maintenance. Italy's intricate road system has a large number of existing bridges demanding urgent and costly maintenance interventions. This study presents a critical review of several defects inspected on existing bridges located in the Basilicata region. The work is addressed at describing the defects surveyed, and at critical evaluating the main causes also due to the interaction with the environmental context surrounding each bridge analysed. Moreover, the paper discusses on how the detailed context knowledge can help to properly identify the correct maintenance intervention on existing bridges
Structural defects for condition assessment of existing bridges: some results of a territorial case study.
Full text linkRecent events involving the tragic collapse of existing bridges have led to an increasingly detailed study of infrastructure and its maintenance. Italy's intricate road system has a large number of existing bridges demanding urgent and costly maintenance interventions. This study presents a critical review of several defects inspected on existing bridges located in the Basilicata region. The work is addressed at describing the defects surveyed, and at critical evaluating the main causes also due to the interaction with the environmental context surrounding each bridge analysed. Moreover, the paper discusses on how the detailed context knowledge can help to properly identify the correct maintenance intervention on existing bridges
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