1,721,083 research outputs found
Lateral strength Of urm piers: comparison between codified criteria and in-plane test results
No full textThe lateral resistance represents one of the most significant wall parameters to be used in the seismic analyses for the design/assessment of masonry buildings. In this article, an investigation on in-plane lateral strength of URM piers has been proposed thorough a comparison between the results from codified criteria and the outcomes of several experimental in-plane cyclic tests on masonry walls. In this context, a new database collecting the results of in-plane cyclic tests on unreinforced masonry piers, carried out within different research projects, has been devel-oped. The database consists of walls with bricks and blocks with different masonry materials (clay, lightweight aerated concrete, AAC, calcium silicate), bed-and head-joint typologies, di-mensions, boundary conditions, vertical applied loads and horizontal loading history. This source of information of consistent and reliable test results represents a necessary step into the process of definition of shared rules in the European context.Accepted Author ManuscriptApplied Mechanic
Application of seismic design procedures on three modern URM buildings struck by the 2012 Emilia earthquakes: inconsistencies and improvement proposals in the European codes
No full textThe seismic performance of three modern unreinforced masonry buildings struck by the earthquake sequence of May 2012 in Emilia (Italy) has been investigated, to define the safety margins and possible critical issues in the seismic design according to the European seismic codes. The selected structures have been redesigned, applying linear and static nonlinear analyses, and verified against collapse according to both Eurocodes 6 and 8 and Italian Norms for Constructions. The design has provided inconsistent results, in particular with the application of Eurocodes, where none of the three buildings fulfilled the safety checks even at very low lateral action, although two of these structures did not attain any visible damage after the events of May 2012. The requirements of the Italian seismic code have provided, at least for static nonlinear analyses, results more in line with the actual seismic response of the buildings. The main issues and some proposals for the improvement of the codified procedures for seismic design of unreinforced masonry buildings are finally discussed
Innovative solution for seismic-resistant masonry infills with sliding joints: in-plane experimental performance
No full textWithin the European FP7 Project “INSYSME”, a new seismic-resistant clay masonry infill system was conceived with the purpose of controlling damage in the masonry and reducing detrimental effects of the panel-frame interaction, through a combined use of sliding joints inserted in the masonry and deformable joints at the wall-frame interface. Although the idea behind the proposed solution stems from principles already implemented in the past, the originality of this work lies in the innovative development of the materials and of the construction details of the components. In order to assess the seismic performance of this new system, in-plane cyclic tests on one-storey one-bay RC frames with two different infill configurations (one solid and one with a central opening) have been performed within the framework of a wider experimental campaign and are discussed here. These in-plane test results have proved the ability of the proposed solution in limiting the level of damage along with the attainment of a wide margin towards the life safety requirements in comparison with traditional infill systems. Although design and construction optimization of the solution still needs to be further implemented, the results of the in-plane tests appear very promising about its use as an efficient seismic resistant non-structural component in RC buildings
In-Plane Cyclic Response of New Urm Systems with Thin Web and Shell Clay Units
No full textThe use of thin web/shell clay unit masonry is becoming increasingly widespread for its good thermal and acoustic insulation performance. However, vertical perforated clay units with thin webs/shells could be a source of weakness and brittleness when used in load-bearing masonry walls subjected to shear cyclic excitations. The aim of this research is therefore to study the applicability of such construction systems in moderate to medium seismic areas, evaluating their seismic performance through an experimental investigation followed by a numerical research. In this context, the paper will present the results of the in-plane test campaign on 16 masonry piers representing three different masonry typologies, assembled using vertically hollowed clay units with thin webs and shell and tested under controlled boundary conditions, with different in-plane slenderness ratios and different applied vertical loads. The results are discussed in terms of in-plane failure modes, associated lateral strength and stiffness, displacement and dissipation capacity, comparing the performance within the three different typologies and with similar masonry tested in the past with clay units having common (thicker) webs and shells. The main experimental outcomes show that the considered typologies provide a sufficiently good lateral performance, providing stiffness, resistance, deformation capacity and post-peak behaviour in line with the corresponding “traditional” masonry systems without any source of additional brittleness
Local effects on RC frames induced by AAC masonry infills through FEM simulation of in-plane tests
No full textUnreinforced masonry infills are widely used in many parts of the world and it is common practice for seismic design to use simplified methods that usually do not take into account the interaction between the infill and the structure. Starting from the 1950s, many researchers have investigated the lateral response of masonry infills focusing on several different topics. The scientific interest on masonry infills is continuously raising due to the unsatisfactory seismic response of the infilled frame structures observed during post-event inspections and to the difficulty to contrive a widely scientifically and practical recognized solution. Although some modern codes consider the presence of infills with some specifications to prevent damage in the masonry panels and global and local effects on the structure, an effective evaluation of these detrimental effects has not been achieved yet. Within this paper, a FEM simulation of in-plane pseudo-static cyclic tests on a RC frame specimen infilled with unreinforced Autoclaved Aerated Concrete (AAC) masonry infill has been performed in order to study accurately the influence and the interaction of the infill with the RC structure. The experimental results performed by Calvi and Bolognini (J Earthq Eng 5:153–185, 1999), and Penna and Calvi (Campagna sperimentale su telai in c.a. con tamponamenti in Gasbeton (AAC) con diverse soluzioni di rinforzo” (in Italian), 2006) on one-bay one-storey full scale specimens are taken as reference. Non-linear static analyses using a “meso-modelling” approach have been carried out. The masonry used in the model has been calibrated according to tests of mechanical characterization and to in-plane cyclic tests on load-bearing AAC masonry conducted by Costa et al. (J Earthq Eng 15:1–31, 2011). The analyses performed have allowed to investigate the local effects on the frame and, in particular, the changes in the moment and shear demands on the RC elements due to the presence of the AAC infill in comparison with the ones in the bare structure, and to estimate the thrust and the contact length activated by the infill on the frame
Development of a dataset on the in-plane experimental response of URM piers with bricks and blocks
No full textIn this paper, a dataset collecting the results of in-plane cyclic tests on unreinforced masonry piers, carried out within different research projects, is presented. The dataset includes brick and block walls with different materials, bed-and head-joint typologies, dimensions, boundary conditions and vertical applied loads. The development of such dataset aims at providing a tool for the improvement of the understanding and the evaluation of the main parameters that may influence and govern the lateral response of the URM piers under seismic excitation. A preliminary investigation on the in-plane lateral strength and displacement capacity, being two of the most significant parameters used in seismic analyses for the design and assessment of masonry buildings, has been proposed. The dataset, that already groups several specimens, is freely shared and might be continuously updated. This source of information of consistent and reliable test results represents a necessary step into the process of definition of shared rules within the scientific and technical community, in particular for the improvement of codified criteria, analytical and numerical models and testing procedures.Applied Mechanic
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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