1,720,963 research outputs found
Structural Behaviour of Masonry Newly Concept Vault Through Tilting Table Testing on a Scaled Model
No full textMasonry vaults represent one of the most recurrent types of horizontal structural elements in architecture in European countries, even in areas characterized by a high level of seismicity. Therefore, the evaluation of their structural safety and their mechanical behaviour remains of primary importance. This paper proposes to apply already consolidated structural analysis methodologies on a contemporary vaulted space. The aim, therefore, is to investigate the dynamic behaviour of a newly concept vault generated starting from the “Flat vault of Abeille” patented in 1699. The reinterpretation of this vault and its use would allow both to enhance the existing Architectural Heritage and to characterize the realization of new buildings using traditional construction materials and techniques, without going against the canons and guidelines of architectural restoration. It follows that the identification of this “new type” of vault is essential to design it correctly and to optimize the geometry for structural purposes. The present paper describes the results of an experimental campaign about tilting table tests on a 1:8 small scaled vault and and the numerical simulation of the model through the Distinct Element Method (DEM). The physical model is coherent with the numerical one because it has been realized with 3D printed blocks assembled with dry joints. The seismic behaviour of the vault was experimentally studied through quasi-static tests by means of a tilting table to evaluate the collapse angle and the Horizontal load Multipliers for different in-plane angles in order to define a resistance domain of the vault
A dynamically validated model verified by drone photos of the masonry bridge of the XIX century
No full textThe paper presents the results obtained after a preliminary relief of a masonry bridge of the XIX century (1847-1849) made by mean of a series of photos by Unmanned Aerial Vehicles (UAV) technique useful to obtain a 3D Finite Element model of the bridge. Also, the information on the materials and structural details were obtained from a deep archival investigation to build a
consistent numerical model of this historic bridge. The photos obtained by UAV technique then return an AutoCad model. The
bridge is made of white limestone, it has three spans with barrel vaults on lowered arches, each about 3.50 m wide and a span
length of about 7.90 m. The overall length of the bridge is equal to 35 m and 7.5 m high. The results will be useful for the
preliminary numerical model for the subsequent tests campaign to investigate the dynamic characteristics of the bridge. The
present research focuses on having identified a new methodology for exporting a simple model bridge that can also be applied to more complex historical buildings
Satellite Data for Structural Monitoring of Historical Building: The Temple of Minerva Medica in Rome
No full text-The Differential Synthetic Aperture Radar Interferometry is a remote sensing technique to acquire deformation velocity and displacement time-series of large territorial areas. The aim of this work is to develop operational methodologies that allow to assess the structures conservation state by integrating information from traditional monitoring systems with the remote sensing application, in order to monitor permanently structures and infrastructure with a historical relevance and developing specific maintenance programs. It is verified that this processing technique is an adequate tool, even in real-time, to monitor any damage or potential critical issues in the case of exceptional events such as earthquakes or landslides. The case study is the Temple of Minerva Medica in Rome, a masonry building characterized by an important historical-artistic value. The data-analysis shows as the use of satellite monitoring can be a valid tool for the structural safety, allowing to identify a vulnerability map of archaeological sites and historical buildings. The data interferometric processing was carried out using a Graphic Information System (GIS) software
Statistics of wind-induced vibrations for a flexible roof
Full text linkThe wind-induced vibration of flexible structures is an important topic in the field of wind engineering in terms of human comfort and safety and of global instability of cable structures. In particular, cable structures used for roofs, for example, cable net and membrane tensile structures, are very sensitive to wind-induced vibrations because the axial force in a cable depends on its geometry. When the cable changes its geometry during the vibrations, it may either lose its tension or the cable tension may exceed the cable's material strength. The wind-structure interaction on flexible roofs is most frequently investigated through numerical analyses using forces time-histories calculated by aerodynamic tests on rigid models. However, this approach fails to predict the effective dynamic deformation of the roof. This paper discusses results obtained from aeroelastic tests in a wind tunnel on flexible roofs. Signals were divided into slots and the statistics of peaks were estimated and discussed through the cumulative distribution function plot. Quantiles of 79%, 93% and 95% of the wind-induced acceleration were compared with the values provided in literature, codes and standards. The comparison showed that the values of accelerations provided in the literature are underestimated
Parameterization and Mechanical Behavior of Multi-block Columns
No full textThe research aims at studying the mechanical behavior of a monumental structure to preserve the historical-architectural heritage as recommended by the Sustainable Development Goal 11.4 to “strengthen efforts to protect and safeguard the world’s cultural and natural heritage”. This research focuses on multi‐drums classical columns, a very common typology in the architecture of ancient Mediterranean civilizations. These columns are made of stone drums of considerable size compared to its entirety, thus, their resistance to vertical and horizontal loads is entrusted to simple support and friction between the drums. So, the present paper proposes a parametric study of the geometrical characteristics, mechanical properties and interactions of the blocks with the aim of describing their influence on the dynamical response of columns, highlighting fundamental aspects concerning their vulnerability. The analysis is performed by means of the Distinct Elements Method (DEM). Many numerical analyses have been conducted to investigate the effects of parameters that influence the dynamic behavior of the examined structural elements and identifying their stability domains
Dynamic identification of a strategic building of the sixties with a mixed structure
Full text linkThe present paper shows and discusses the results of the identification procedure applied to the building of the Municipality of Castellaneta, Taranto (Puglia, Italy). The case study has been chosen for its structural complexity; indeed, the building has been built in two successive phases, block A built between 1955 and 1957, and block B, for completion, presumably built between the years 1960 and 1961. Block A constitutes the main building and represents the original nucleus. The structure was subsequently subject to structural interventions to replace some load-bearing walls with steel beams. The building constituting block B, joined to the original body of the building, has a structure in load-bearing masonry, while the floors, more recently built, are also in brick-concrete, but with pre-cast prestressed joists. The dynamic response of the building was assessed through OMA (Operational Modal Analysis) identification technique which allows you to determine the properties of the structure in real operating conditions, without the need to interrupt the activities inside the structure itself. The structural excitement, therefore, is due only to the environmental condition. A 3D model was defined in PRO_SAP; the results obtained from the finite element model were subsequently compared with those obtained from the experimental model
Essential dynamic characterization of a historical bridge: integrated experimental and numerical investigations
No full textThis paper reports on a series of experimental tests and a numerical study carried out on the historic masonry bridge of Santa Teresa of Bitonto, located in Bari (Southern Italy). A systematic working technique was planned and carried out with the final objective of defining the dynamic properties of the bridge and verifying the seismic repose by means of a response spectrum analysis. Initial stages were carried out including historical research, visual inspection, and geometric integrated aerial and ground survey on-site using UAV technique for the identification of the geometric details of the structural and non-structural elements of the bridge. An experimental campaign was scheduled and executed by performing free and forced-vibration tests using uniaxial and biaxial accelerometers placed at 22 monitoring points to retrieve the main vibration modes of the bridge with their corresponding frequencies and damping ratios. Although the free vibration tests detected only the main mode of vibration due to the squat nature of the structure, the forced-vibration tests help to confirm the findings and identify further modes of vibration. The consistency of the experimental frequencies was statistically confirmed by varying the conditions of the forced-vibration tests. A Finite-Element (FE) model was constructed and calibrated qualitatively (i.e., order of vibration modes) with respect to the experimental ones, based on both the geometric survey and the visual inspection outputs. Then, a second phase of calibration was undertaken by tuning the remaining free parameters to match the numerical values of all the detected modes. The calibrated model, capable of producing the experimental results, was adopted for performing a response spectrum analysis for the global response evaluation of the bridge. The results showed a globally acceptable level of stress, while excessive values were limitedly observed in a few critical zones
Exploring multi-hazard effects on a tall building and its non-structural elements through simultaneous earthquake and wind loading
No full textThe tall building construction sector has recently exhibited an increasing development, especially in Europe. This activity is aligned with European policies regarding soil conservation and social housing. Due to their slenderness, such structures are particularly sensitive to wind and earthquake loads. Nevertheless, current building codes, standards, and most scientific literature neglect the interaction of these events as simultaneity has always been considered a rare design case due to the limited effect on the structural elements. The present work carries out a careful statistical investigation on the occurrence of strong earthquakes accompanied by a wind load event, characterized by non-negligible daily mean-wind velocities in Italy, where more than one-third of its area is occupied by high mountains, limiting the urban development to confined zones. Subsequently, the effect of the simultaneous occurrence of earthquake and wind loads has been studied, both from the numerical and experimental points of view (i.e., shaking table and wind tunnel tests) to evaluate the consequences on structural and non-structural elements (e.g., façades) of a building case study. Results show that the cumulative effect of typical and non-catastrophic daily mean wind velocity (i.e., in the range of 5–10 m/s at 10 m from the ground) and a typical and non-catastrophic seismic daily shock (i.e., with magnitude in the range of 3–5), can trigger large inter-story drift ratio values and fatigue, causing damage to non-structural elements - like façades - and consequently a risk for occupants and high economic losses
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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