Micro and Macro-modeling Techniques for the Simulation of the Masonry Infilled R/C Frames under Earthquake Type Loading (original) (raw)
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Buildings, 2020
Reinforced concrete (RC) frame buildings with masonry infills represent one of the most common structural typologies worldwide. Although, in the past, masonry infills were frequently considered as non-structural elements and their interaction with the structure was neglected, earthquakes occurring over the last decades have demonstrated the important role of these elements in the seismic response of all RC-infilled building typologies. In this regard, the selection of the most suitable numerical modelling approaches to reproduce the hysteretic response of the masonry infills—and their interaction with the RC frames—is still an open issue. To deal with this issue, in this study, a macro-classification based on different available databases of experimental tests on infilled RC frames, is firstly proposed to understand the variability in the infill properties and the corresponding numerical modelling uncertainties. Five masonry infill types are selected as representative for the typica...
Engineering Structures, 2017
Reinforced concrete frames with unreinforced masonry infill walls represent a widely adopted building system. During seismic events, infill walls, usually considered as non-structural elements, may significantly affect the characteristics of the system in terms of in-plane stiffness, strength, and energy dissipation capacity. The assessment of framed structures infilled with unreinforced masonry walls has been investigated since the 1950s. Developing reliable numerical models of infill walls has become an important issue since then. The analytical simplified model based on equivalent diagonal struts is often used to assess the infilled frames response. The nonlinear behavior of the equivalent diagonal strut is usually described by constitutive laws that account for the stiffness, the strength and the hardening or softening behavior of the infill. The present work focuses on the evaluation of various parameters needed to define the monotonic and hysteretic response of infill walls modelled by equivalent struts. In order to select a simple and reliable analytical model that suitable for representing the infill wall response, different strut formulations and hysteretic models have been analysed in detail and used to reproduce several experimental tests available in the literature. The numerical analyses are performed by means of the OpenSees computer program. Three uniaxial material models available in OpenSees are used to assess their capability in reproducing the experimental hysteretic response. Finally, from the comparison among different models and between numerical and experimental results, suggestions are made to properly model the in-plane non-linear response of infills.
Numerical Analysis of In-plane Behaviour of Masonry Infilled Rc Frames Using Macro And Micro Models
2020
A number of simplified methodologies have been proposed aiming at preparing numerical tools suitable for engineering application, to predict the nonlinear seismic behavior of infilled frame structures. In this paper, a 2D discrete macro element model (DMEM) for the simulation of the in-plane behavior of RC frames with infill walls, is presented, validated with an experimental result that investigate the influence of infill masonry, and evaluated with a proposed Finite Element model (FEM). In this model, the frame members are modeled by beam-column elements with lumped plasticity, while the infills contribution are modeled by plane discrete-element. As an extended study, a 2D prototype of multistory frame building, for which the results of pseudo dynamic tests are available, is investigated. The ability of the considered DMEM to predict the in-plane behavior of infill masonry elements is investigated, the merits and drawbacks are highlighted.
Numerical Modeling of Masonry-infilled RC Frame
The Open Construction & Building Technology Journal, 2019
Background:The behavior of masonry-infilled Reinforced Concrete (RC) frame structures during an earthquake, has attracted the attention of structural engineers since the 1950s. Experimental and numerical studies have been carried out to investigate the behavior of masonry-infilled RC frame under in-plane loading.Objective:This paper presents a numerical model of the behavior existing masonry-infilled RC frame that was studied experimentally at the University of Patra. The objective of the present study is to identify suitable numerical constitutive models for each component of the structural system in order to create a numerical tool to model the masonry infilled RC frames in-plane behavior by accounting the frame-infill separation.Methods:A 2D masonry-infilled RC frame was developed in DIANA Finite Element Analysis (FEA) software and an eigenvalue and nonlinear structural cyclic analyses were performed. It is a 2:3 scale three-story structure with non-seismic design and detailing, ...
Behavior Of Bare And Masonry InfilledR/C Frames Under Cyclic Loading:Experiments And Analysis
WIT Transactions on the Built Environment, 2005
In this study an analytical investigation and experimental verification of the influence of infill panels on the seismic behavior of reinforced concrete frames is presented. The project includes three 1/3-scale, single-story, single-bay reinforced concrete frame specimens subjected to lateral cyclic loading; one infilled frame specimen with clay brick solid masonry and two bare frame specimens one with transverse steel in the form of common stirrups and one with continuous rectangular spirals of the same spacing. Special elements are employed for the modeling of the examined specimens. Beam and columns were modeled using elements with distributed plasticity. For the contribution of the behavior of the infill to the response of the frame the equivalent diagonal strut model is used. Two different types of elements were employed for this purpose. The first element is an inelastic truss element with bilinear brittle response. The second one is an inelastic element with response that can...
2020
This paper deals with the applicability of a non-linear masonry-infill concrete-frame numerical simulation to predict realistically the seismic behaviour of model three story R/C frame structural formations with masonry infills. The major obstacle here is the computational time and memory requirements needed for the completion of such a numerical analysis including all the non-linear mechanisms which were employed in the preceding simulation of the single-story onebay R/C frame with masonry infills. A numerical technique is proposed that draws information from the fully inelastic numerical simulation of the masonry infilled R/C frame in order to define the mechanical properties of an equivalent diagonal strut that represents the masonry infill. In order to overcome this obstacle, use was made of an equivalent nonlinear diagonal strut model that draws information on the stiffness and strength variation from one-bay, one-story R/C masonry infilled unit. This simplified methodology inc...
Frontiers in Built Environment, 2020
The threat to human lives and the economic losses due to high seismic vulnerability of non-engineered traditional masonry infills subjected to earthquakes have been highlighted by several post-seismic surveys and experimental and numerical investigations. In the past decades, researchers have proposed different techniques to mitigate problems related to the seismic vulnerability of traditional masonry infills; however, a viable, practical, and universally accepted solution has not been achieved yet. Among the possible innovative techniques, the one using ductile (or pliable) infills have shown promising results in recent experimental tests. These infills have provided, indeed, a reduced in-plane stiffness and a very high displacement capacity. The research units of the University of Pavia/EUCENTRE (Italy) and the University of Newcastle (Australia) have proposed two different systems for ductile masonry infill based on dividing the masonry panel into a number of segments interconnec...
Evaluation of Diagonal Strut Models for Different Masonry Infill Conditions inside R/C Frames
2018
The influence of the masonry infills inside R/C frame structures under seismic type loadings is a subject that many modern seismic codes and provisions are newly focusing. Various researchers have proposed analytical expressions that accompanied the evolution of seismic codes in an effort to determine both the initial stiffness of the infill panels and their bearing capacity. However, in most of these provisions the influence of the joint interface between the masonry infill and the surrounding frame is ignored. In this study the ability of various proposed methodologies to predict the influence of the masonry infills is examined. Numerical simulations of the masonry infilled R/C frames are proposed that are evaluated against experimental results of a number of 1: 3 scaled masonry infilled R/C frame specimens tested at the Laboratory of Strength of Materials and Structures (LSMS) of Aristotle University under seismic-type loading. In these cases the predicted numerical behaviour of ...
Modeling of masonry of infilled frames, Part II: Cracking and damage
Engineering Structures, 2009
This paper proposes a model of the behavior of infill panels in framed structures. The model is based on the equivalent strut model, the concept of a plastic concentrator, and damage mechanics. First some fundamental concepts of damage mechanics are briefly presented. Then, an experimental study of the behavior of masonry specimens under compression forces is described. These results are used for the development of the constitutive law for the equivalent strut bars. The model is analyzed, first in the case of monotonic loadings, and then for cyclic loadings. Finally, the model is validated by numerical simulation of a test carried out on infilled frames subjected to monotonic and cyclic loadings.
Experimental tests and global modeling of masonry infilled frames
The effects of infill panels on the response of r.c. frames subjected to seismic action are widely recognized. Numerous experimental investigations were effected and several analytical models were developed on this subject. This work, which is part of a larger project dealing with specific materials and structures commonly used in Italy, discusses experimental tests on masonry and samples of bare and infilled portals. The experimental activity includes tests on elemental materials, and 12 wall samples. Finally, three one-bay one-story reinforced concrete frames, designed according to the outdated Italian technical code D.M. 1996 without seismic details, were tested (bare and infilled) under constant vertical and cyclic lateral load. The first cracks observed on the framed walls occurred at a drift of about 0.3%, reaching its maximum capacity at a drift of 0.5% while retaining its capacity up to a drift of 0.6%. Infill contributed to both the stiffness and strength of the bare reinfo...