Search results for "Infill"
showing 10 items of 43 documents
Empirical Equations for the Direct Definition of Stress–Strain Laws for Fiber-Section-Based Macromodeling of Infilled Frames
2018
Equivalent strut macromodels are largely used to model the influence of infill walls in frame structures due to their simplicity and effectiveness from a computational point of view. Despite these advantages, which are fundamental to carrying out seismic simulation of complex structures, equivalent struts are phenomenological models and therefore have to conventionally account for the influence of really large amounts of geometrical and mechanical variables with a relatively simple inelastic response. Mechanical approaches, generally used to evaluate the force-displacement curve of a strut, are based on hypothesizing the damage mechanism that will occur for an infill-frame system subject to…
Definition of a fiber macro-model for nonlinear analysis of infilled frames
2017
A common way to model infill-frame interaction is the use equivalent strut macromodels. In most cases these are compression only resistant truss elements defined with a multi-linear axial-force / axial-displacement law. The main difficulty in using this approach is to correctly calibrate such a force-displacement curve (slope of ascending and post-peak branches, critical yielding, peak and residual forces) because of the large number of variables (mechanical and elastic properties of materials) and the different possible damage mechanisms activated for the frame-infill system. Another possible way is using fiber-section elements as diagonal struts. In this case the force-displacement law is…
Macroelement Model for the Progressive-Collapse Analysis of Infilled Frames
2021
A new multistrut macromodel for the analysis of the progressive-collapse response of infilled reinforced concrete (RC) frames is presented in this paper. The model consists of three struts: two outer infinitely rigid and resistant struts and one inner fiber-section strut. The inclination of the struts as well as the stress-strain response are modulated by two parameters that are obtained by means of analytical correlations provided in the paper. The latter link the geometric and mechanical properties of an infilled frame to the geometric configuration and mechanical response of the equivalent strut model. This confers the model the capability to adapt to consider different collapse configur…
Out-of-Plane Behavior of URM Infill: Accuracy of Available Capacity Models
2022
The aim of this paper is to check the accuracy of analytical capacity models available for the prediction of out-of-plane strength of unreinforced masonry (URM) infill walls. The accuracy of the available models is checked by detailed comparison with the existing experimental results. In doing so, both types of capacity models are evaluated: Type I for the prediction of the strength in the undamaged state, and Type II for the prediction of strength reduction in the in-plane damaged state. Results from the calculations are discussed, and the best among the available models are recommended. Furthermore, the influence of orthotropy of the infill masonry in the out-of-plane capacity predicted b…
Influence of column shear failure on pushover based assessment of masonry infilled reinforced concrete framed structures: A case study
2017
Structural frames, constructed either of steel or reinforced concrete (RC), are often infilled with masonry panels. However, during the analysis of the structural frames, it has become common practice to disregard the existence of infills because of the complexity in modeling. This omission should not be allowed because the two contributions (of infills and of frames) complement each other in providing a so different structural system. The use of different modeling assumptions significantly affects the capacity as well as the inelastic demand and safety assessment. In specific, the adoption of equivalent diagonal pin-jointed struts leaves open the problem of the evaluation of the additional…
Prediction Equations for Out-of-Plane Capacity of Unreinforced Masonry Infill Walls Based on a Macroelement Model Parametric Analysis
2021
In the seismic performance assessment of reinforced concrete (RC) frames, a reliable estimation of the capacity of unreinforced masonry (URM) infill walls is of utmost importance to ensure structural safety conditions. With particular attention to the out- of-plane (OoP) capacity of URM infill walls after in-plane (IP) damage, the issue of defining reliable analytical prediction models for the assessment of the capacity is an ongoing study. In this paper, empirical equations are proposed for the evaluation of the infilled frame’s OoP capacity, with or without IP damage, based on an extensive numerical parametric analysis, focusing on the influence of the key parameters that govern the mecha…
A semi-empirical stress-strain model for equivalent strut fiber-section modeling of infilled frames
2017
Infill-frame interaction is commonly modeled by means of equivalent strut macro-models. The main difficulty in using this phenomenological approach is to properly calibrate a force-displacement curve for the struts, as this depends not only on the geometrical and mechanical properties, but more specifically on the different potential damage mechanisms which may occur for the infill-frame system subject to lateral forces. If fiber-section elements are used as diagonal struts, the force-displacement curve is substituted by a stress-strain law. In both cases, the attribution of the inelastic law of the struts, based on a mechanical approaches, is not valid in general, as mechanical approaches …
EVALUATION OF FRAGILITY OF INFILLED FRAME STRUCTURES SUBJECT AFTERSHOCKS BY MEANS OF DOUBLE INCREMENTAL DYNAMIC ANALYSIS APPROACH
2018
The paper investigates the role of masonry infill walls on the seismic fragility of reinforced concrete structures subject to mainshock/aftershock sequences. An assessment framework aimed at determining aftershock fragility curves of bare frames and infilled frames is presented. The framework is based on a Double Incremental Dynamic Analysis (D-IDA) approach, which provides the adoption of ground motions defined by combining a fixed intensity mainshock with a set of variable intensity aftershocks. Mainshock (MS) intensity is scaled several times and combined with the same set of aftershocks (AS). Chord-rotation and shear limit states are specifically defined to consider the influence of mas…
Macroelement Model for In-Plane and Out-of-Plane Responses of Masonry Infills in Frame Structures
2018
A new macroelement model is presented in this paper for the simulation of the in-plane (IP) and out-of-plane (OOP) response of infilled frames subjected to seismic actions. The model consists of two diagonal, one horizontal, and one vertical struts. Each strut is represented by two fiber-section beam-column elements. The model is able to capture the arching action of the wall under an OOP load as well as the interaction between the IP and OOP actions. The proposed modeling approach is sufficiently simple and efficient that it can be used for the static or dynamic analysis of an entire structural system. An experimental validation has been carried out. A further numerical study performed wit…
Definition of diagonal Poisson's ratio and elastic modulus for infill masonry walls
2014
The prediction of the response of infilled frames through the simplified approach of substituting the infill with an equivalent pin-jointed strut is treated. In this framework the results of an experimental study for the mechanical characterization of different types of masonry infills having the aim of estimating strength, Young modulus and Poisson's ratio are presented. Four types of masonry were investigated and subjected to ordinary compressive tests orthogonally to the mortar beds and along the directions of the mortar beds. The experimental campaign confirmed the possibility of using an orthotropic plate model for prediction of the Poisson's ratio and Young modulus along the diagonal …