1,721,017 research outputs found
ANALYTICAL MODEL FOR PREDICTING OOP LATERAL BEHAVIOR OF MASONRY INFILL WALLS
No full textThe use of clay masonry infill walls in reinforced concrete (RC) frames is a common construction practice worldwide. These still represent a potentially critical problem for the overall seismic performance of buildings. This is because they are often overlooked in design procedures, being generally classified as nonstructural elements. However, their brittle behavior makes them easily damaged, resulting in a loss of building functionality and significant economic losses even at low to medium seismic intensities. This paper aims to present a recently developed analytical model for estimating the lateral OOP response of various masonry infill walls; it implements the vertical and horizontal arch mechanisms, taking into account the plate effect, the deformability of the upper beam, and the presence or absence of external reinforcement. This analytical model was calibrated in this study for some types of thin infill walls, both unreinforced and reinforced. For illustrative purposes, a parametric analysis using this model is presented, which is useful for discussing the role of the main infill vulnerability parameters on OOP capacity
EVALUATION OF THE INTER-STORY ISOLATION SYSTEM APPLIED TO AN EXISTING RC SCHOOL BUILDING
No full textInter-story Isolation System (IIS) is an interesting technique for the mitigation of the seismic risk of buildings. In existing buildings, this technique can also be effectively used, when properly designed, to add extra stories while reducing the seismic response of the structure, representing an innovative retrofitting strategy. Therefore, IIS is particularly advantageous when it is desired to both increase the volume of the building and improve its seismic behaviour. In this paper, the IIS is used to rise an existing reinforced concrete school building, while improving its overall seismic behaviour. First, a specific superstructure is chosen and the optimization approach for deriving the optimal IIS parameters is presented. Then, based on the optimal results obtained, the IIS is designed, and its effectiveness is investigated by performing Time History analysis, using a set of spectrum-compatible natural records and a fiber modelling of the structure, and comparing the results obtained with and without the IIS
EXPERIMENTAL CALIBRATION OF THE IP BEHAVIOR OF STRENGTHENED INFILL WALLS AND SEISMIC ANALYSIS INCLUDING IP/OOP EFFECTS
No full textThin masonry infills, classified as nonstructural elements, and often neglected in design models, strongly influence the seismic behavior of RC frames by increasing the overall structural stiffness; in addition, they can be the cause of brittle failure mechanisms, such as soft-floor mechanisms. Moreover, given their very brittle behavior and high IP/OOP response interaction, they are easily damaged even at low to medium seismic intensities. As a result, they are responsible for the high loss of building functionality and high repair costs. This paper presents several concentrated plasticity models for representing the IP behavior of different reinforced and unreinforced infills, calibrated for four different panels using experimental tests. The objective is to provide simplified models, using a commercial FEA program, to best represent the nonlinear behavior of the infills. After IP calibration of the panels, the seismic analysis of an existing 6-story frame infilled with unreinforced and strengthened panels is presented. The conducted nonlinear dynamic analysis is aimed at estimating the expected annual loss (EAL), according to Italian guidelines, to evaluate the effectiveness of the adopted strengthening solution
AUTOMATIC IDENTIFICATION OF BUILDING FEATURES FOR SEISMIC DAMAGE ASSESSMENT ON A LARGE SCALE
No full textSeismic risk assessment represents a big challenge in countries with a high seismic hazard and a significantly vulnerable built heritage, such as Italy. When carrying out seismic risk evaluations at large scales, however, the identification of buildings and their features can be very costly and time consuming. In this work, artificial intelligence techniques are used to automatically and remotely retrieve exposure information. First, building data are collected using satellite imagery, then street-view pictures are extracted for each building and Convolutional Neural Networks are trained to recognize specific features of interest, especially those that affect seismic vulnerability. Furthermore, a seismic damage calculation platform is developed. The results provided by this algorithm can be useful for managing emergencies and establishing priority criteria for seismic mitigation strategies
EVALUATION OF THE INTER-STORY ISOLATION SYSTEM APPLIED TO AN EXISTING MASONRY SCHOOL BUILDING
No full textAdding extra stories to an existing building is an interesting application of the Inter-story Isolation System (IIS) that allows to improve the seismic response of existing structures. Assuming that the isolated superstructure is much stiffer than both the isolation system and the existing structure, it behaves like a rigid body, acting as a Tuned Mass Damper for the substructure. Various methods are available in the literature for defining the optimal parameters of the isolation system, but only a few studies focused on this particular application with real case studies. In this paper, this application is shown for an existing masonry school building. The aim of the intervention is to raise the structure, increasing the space available for teaching activities, while also obtaining an improvement in the overall seismic behaviour of the substructure. First, an optimization for calculating the optimal IIS parameters is performed; then, based on the optimal results obtained, the effectiveness of the IIS application is evaluated by performing Time History Analysis, using a set of spectrum-compatible natural records and an equivalent-frame modelling (EFM) of the structure, and comparing the results obtained with and without the IIS
INVESTIGATIONS ON INTER-STOREY SEISMIC ISOLATION AS A TECHNIQUE FOR ADDING UPPER STOREYS
Full text linkThe inter-storey seismic isolation technique is becoming increasingly attractive for the seis-mic risk mitigation of buildings, also as alternative strategy to base isolation. The reasons for applying this technique can be various and of different nature, such as: architectural con-cerns, feasibility of construction, and performance benefits. An interesting application of this technique concerns its use for adding upper storeys to existing buildings, avoiding the in-crease of seismic forces on the substructure, or even reducing them. Therefore, this technique could also be effective for seismic retrofit applications, using the mass of the superstructure as a nonconventional TMD for controlling the dynamic response of the substructure.
Among the main issues concerning this application, there is the need to control the relative displacement between the two structural parts and the acceleration of the superstructure, while improving the seismic performance of the substructure.
In this paper, a multi-objective optimization method for the dynamic characteristics of the ad-ditional superstructure is presented, which uses a TMD approach and considers the perfor-mances of the substructure, isolation system and superstructure. A 3-storey (3 DOF) case study structure was taken as a reference, analysing a wide range of isolated masses, isolation periods and damping ratios. Time-history analyses are finally performed, based on the opti-mization results, in order to assess the effectiveness of both the optimization method and the isolation technique, also considering the structural non-linearity
Automated estimation of building height through image processing
No full textSeismic risk is one of the main problems in highly urbanized countries with a considerable
seismic hazard like Italy. To assess seismic risk of the built heritage, it is necessary to deepen
the knowledge of its components, vulnerability in particular. Vulnerability can be evaluated
through mechanical methods, which require detailed information on parameters that may affect
the seismic response. The implementation of such methods often results in time-consuming and
expensive investigations, thus making the risk assessment analysis very cumbersome.
In order to make this process easier and faster, remote sensing algorithms can be taken into
consideration. In this work, satellite images of areas of interest are automatically extracted via
open source online maps, as well as some preliminary information about the buildings detected
in the pictures. Afterwards, a filter is set in order to visualize only targeted building typologies
(e.g., residential buildings), and street view images are obtained for each selected building.
The images are then processed through feature extraction techniques, in order to predict the
number of stories of the buildings.
The remote and automated retrieval of this feature, along with other meaningful parameters,
could allow the association of a specific vulnerability level for each building, thus making onsite
surveys unnecessary, with a remarkable reduction in time and costs
Fragility curves for Italian residential masonry buildings with retrofit interventions
Full text linkThe earthquakes of the last decades have shown that the Italian residential masonry built her-itage has high seismic vulnerability, in particular when considering structures built before 1919. For this reason, it is necessary to develop effective large-scale risk mitigation strategies in order to reduce the huge losses that could occur in the aftermath of an earthquake. In this paper some retrofit interventions applicable mainly to old buildings are presented, explaining their advantages and potential. These interventions are then implemented, through Vulnus 4.0 software, on a database of 205 buildings built before 1919, previously analyzed in their as-built state.
Fragility curves are then developed for each building, and are processed in order to create a vulnerability model for different construction periods that takes into account the possible ret-rofit intervention strategies. Therefore, this procedure allows a comparison between pre and post retrofit intervention fragility, and the results in terms of curves can be used for large scale damage and risk simulations
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