1,721,018 research outputs found
Displacement Capacity of Load-Bearing Masonry as a Basis for Seismic Design
Full text linkThe masonry still one of the widespread construction system for low-rise residential buildings even for countries prone to seismic risk. Seismic design methods yet in use are based on idea that controlling forces is better way to control earthquake induced damages. In recent decades, however, was highlighted as the differences in strength between two levels of damage is low, and therefore as the damage is better correlated to the displacement. Also, in recent years, has arose a widespread expectation for being able to control the damage based on the probability of occurrence of an earthquake or being able to base the design on different performance levels ("performance-based design").
In this context, the design of masonry buildings needs to develop these design methods. The results of experimental tests performed at the University of Padua in the recent years on different masonry systems both reinforced and unreinforced with different horizontal and vertical joints typologies, which were aimed to characterization under combined in-plane vertical and horizontal cyclic loading, were used to make different strategies of finite element modeling that reproduce and extend the experimental results using parametric analyses. These analyses allow a comparison and a validation of an analytical model which was then developed. This model is able to reproduce the envelope curves of the cyclic shear-compression tests and it is able to interpret the performances of panels linking them with limit states resulting from integration of cross-section equilibrium equations. Finally, it was applied a model able to reproduce the hysteretic behavior of masonry and were carried out dynamic analyses using the input data derived from the envelope curves. The data thus collected can be used as database and as input for displacement-based design methods
Development of a fiber model for load-bearing masonry members
No full textIn the last few years, the possibility of being able to control damage based on the probability of occurrence of an earthquake and designing on the basis of different performance levels, has arose. Masonry is still a widespread construction system for low-rise residential buildings even in earthquake prone countries; hence masonry needs to develop these design concepts.
Experimental tests were performed in recent years at the University of Padova on different masonry systems, both reinforced, and unreinforced with different joint types. The tests were aimed at characterizing the masonry behaviour under combined in-plane cyclic loading, and they were used to develop an analytical model that reproduces the experimental results.
This model is a formulation of a fiber element and is cast in the general framework of the mixed method. It includes effects of shear deformation, diagonal shear failure mechanism and it follows the response in the post-peak phase. The model is able to interpret the performances of masonry panels linking them with limit states resulting from integration of cross-section equilibrium equations
Application of a Newly Fiber Model for Load Bearing Masonry Members
No full textIn the last few years, the possibility of being able to control the damage based on the probability of occurrence of an earthquake and designing on the basis of different performance levels, has arose. Masonry is still a widespread construction system for low-rise residential buildings even for countries prone to seismic risk, hence masonry needs to develop these design concepts.
Experimental tests were performed in recent years at the University of Padova on different masonry systems, both reinforced, and unreinforced with different joints types. The tests were aimed at characterizing the masonry behaviour under combined in-plane cyclic loading, and they were used to develop an analytical model that reproduce and extend the experimental results using parametric analyses.
This model is a formulation of a fiber element and is cast in the general framework of the mixed method. It includes effects of shear deformation, diagonal shear failure mechanism and it is able follow response in post-peak phase. The model is able to interpret the performances of masonry panels linking them with limit states resulting from integration of cross-section equilibrium equations.
The experimental results were extended throughout parametrical analyses using the analytical model and, finally, generalized proposing design equations directly related to performance levels and both geometrical and mechanical properties of URM panels
Development of a fiber model for load-bearing masonry walls
No full textIn the last few years, the possibility of being able to control the damage based on the probability of occurrence of an earthquake and designing on the basis of different performance levels, has arose. Masonry is still a widespread construction system for low-rise residential buildings even for countries prone to seismic risk, hence masonry needs to develop these design concepts.
Experimental tests were performed in recent years at the University of Padova on different masonry systems, both reinforced, and unreinforced with different joints types. The tests were aimed at characterizing the masonry behaviour under combined in-plane cyclic loading, and they were used to develop an analytical model that reproduce and extend the experimental results using parametric analyses. This model is a formulation of a fiber element and is cast in the general framework of the mixed method. It includes effects of shear deformation, diagonal shear failure mechanism and it is able follow response in post-peak phase. The model is able to interpret the performances of masonry panels linking them with limit states resulting from integration of cross-section equilibrium equations. Finally, its results were generalized proposing design equations directly related to performance levels and both geometrical and mechanical properties of URM panels
Calcolo della resistenza fuori piano di tamponature realizzate con il sistema Antiespulsione : modellazione analitica e proposte progettuali
No full textQuesto lavoro parte dai risultati dei test sperimentali condotti su elementi di tamponatura per strutture intelaiate in C.A. realizzati con il sistema Antiespulsione basato sul blocco in laterizio Poroton P69TA di Cis Edil. I test sperimentali hanno investigato il comportamento della tamponatura Antiespulsione nella sua versione armata e non armata, con configurazioni che hanno tenuto conto della presenza o meno di aperture. I risultati di tali test sono stati presentati nel N°114 di Murature Oggi. Nel presente lavoro si descrive un modello analitico, sviluppato e calibrato sulla base dei risultati sperimentali citati, in grado di riprodurre il comportamento delle tamponature nel fuori piano includendo gli effetti dovuti al danneggiamento nel piano. Questo modello è stato poi semplificato in modo da fornire al progettista una formula semplice per la verifica delle tamponature realizzate con il sistema Antiespulsione. Si aggiungono in conclusione alcune considerazioni riguardo gli spostamenti nel piano di strutture a telaio in C.A. tamponate
Report preliminare sul comportamento degli edifici in muratura portante moderni durante la sequenza sismica nella pianura padana-emiliana 2012
Full text linkIn seguito ai devastanti terremoti dell'Irpinia (1976) e del Friuli (1980), il gruppo di ricerca del professor Modena, attivo presso l'Universit\`a degli Studi di Padova, ha indirizzato la propria attenzione sugli aspetti strutturali e sul comportamento sismico degli edifici in muratura, sia storiche che di nuova costruzione. La sequenza sismica che ha colpito l'Emilia Romagna lo scorso maggio ha causato danni molto gravi a diverse tipologie di edifici, non solo edifici storici ma anche moderne strutture prefabbricate industriali. In questo contesto, una squadra di rilevatori ha compiuto diversi sopralluoghi ad edifici residenziali, realizzati in muratura portante, al fine di comprendere come questa soluzione costruttiva abbia reagito al terremoto
Effectiveness of plasters and textile reinforced mortars for strengthening clay masonry infill walls subjected to combined in-plane/out-of-plane actions
No full textThis work presents the results of experimental tests on full-scale one-bay, one-storey reinforced concrete (RC) frames, filled with non-load-bearing clay masonry walls. The infill walls were made with clay masonry units characterized by a high percentage of voids and low strength. Such ‘light’ infill walls have shown fragile behaviour during recent earthquakes, due to the combined effects of damage produced by out-of-plane seismic action, together with in-plane deformation of the RC frame. In this context, various solutions to the problems involved in external reinforcement of ‘light’ infill walls, typically found in existing
RC buildings but still used in common construction practice, have recently been developed. These solutions are: i) special lime-based plaster with geo-polymer binder; ii) bidirectional composite meshes applied with inorganic matrices, i.e., Textile Reinforced Mortars (TRM); iii) TRM improved by anchorage of the mesh to the RC frame. For these construction elements, a special set-up for combined in-plane/out-of-plane cyclic testing, already used for other infill wall types at the University of Padova, was used. In particular, this work describes: a) materials and systems for strengthening infill walls; b) experimental results of infill walls under in-plane loads; c) effects of out-of-plane loads on previously in-plane damaged infi ll walls. The final aim was to achieve complete mechanical characterization of infill walls in both original and strengthened conditions, and to validate the effectiveness of the proposed strengthening systems
In-plane behavior of clay masonry walls: experimental testing and finite element modeling
No full textExtensive experimental research aimed at defining the in-plane cyclic behavior of three types of load-bearing masonry walls, assembled with perforated clay units, and various types of head and bed joints was carried out. Experimental behavior was modeled with four types of nonlinear finite-element models. Both macromodeling and micromodeling strategies, implementing either isotropic or orthotropic material laws, were adopted. Two simplified criteria were proposed for calibrating the models, one for defining orthotropic properties starting from perforated unit geometry and the other for defining expanded unit and interface element properties in micromodels. The procedures adopted for model calibration established the reliability of various modeling strategies. Results allow some conclusions to be drawn about the reliability of diagonal compression tests for large unit masonry, the stress distribution and different behaviors of masonry made with different head and bed joints, and the influence of unit strength on the in-plane behavior of masonry
In-Plane Behavior of Reinforced Masonry Walls: Experimentally Based Modelling
No full textIn the framework of a recent EU funded research project, innovative construction systems for clay unit reinforced masonry walls were developed. In particular, one system was developed for low-rise residential buildings. An extensive experimental program was mainly aimed to understand the cyclic in-plane behavior under shear and compression loads. The tests results were compared with code proposed formulations for the evaluation of shear strength, in order to check their reliability in predicting the ultimate load capacity of reinforced masonry walls. A new calibrated formulation is proposed. A FE continuum micromodel was calibrated on the experimental results and then used to carry out parametric analyses of the reinforced masonry system, to investigate the influence of the axial load level, the aspect ratio and the reinforcement ratio on the global in-plane behavior of the tested walls. A new analytical hysteretic model was also developed and used to carry out non-linear dynamic analyses of SDOF systems, to evaluate the reduction of the elastic response of reinforced walls, for a range of natural periods that characterize the elastic phase of load bearing masonry buildings
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