A Study of the Effect of Infilled Brick Walls on Behavior of Eccentrically Braced Frames Using Explicit Finite Elements Method

Abstract

Problem statement: Eccentrically Braced Frames (EBFs) are usually infilled by masonry walls, but in common design, the stiffness and lateral resistance of these walls is ignored. Considering the results of carried out tests and studies, it seems that infilled masonry walls have a significant influence on the stiffness and the strength of EBFs. Since experimental test of total frame with infilled brick wall is a very expensive and time consuming process, proper numerical models which can precisely simulate the behavior of EBFs considering the effects of infilled brick wall are necessary. Approach: In this study, a proper model is made using explicit finite elements method to study the behavior of EBFs with infilled masonry wall. Because of complicated mechanical and geometrical properties of masonry walls and also because of the interaction between steel frame and masonry wall, this model is not easy to obtain. To ensure the ability of the model to precisely simulate the behavior of an EBF with infilled brick wall, initial models were made and the problems were solved comparing the results of experimental test and the results of these initial models. Firstly, material models and some basic principles of explicit finite element algorithm are used and three initial models were made: a model of a brick wall without eccentrically braced steel frame, a model of an EBF without infilled brick wall and finally a model of an EBF with infilled brick wall. Results: Using these three initial models, constitutive model for masonry and steel material and also the proper elements for modeling the behavior of mortar is obtained. Studies showed that good prediction of the behavior of a system consisting of EBF and masonry wall is possible, by minimizing the kinematical energy and using a special time scaling of explicit finite element model. Conclusion: After verifying the finite element models, the influence of masonry infilled wall on the behavior of eccentrically braced frames is studied. This investigation showed that in general, the presence of masonry wall increases the yield strength and the elastic range in the force-displacement curves. But the plastic behavior of the frame is deteriorated and due to fragile behavior of masonry materials, the total system of steel frame and masonry wall has a significant strength fall when the elastic range is passed.

Effect of Masonry Infill Walls with Openings on Nonlinear Response of Steel Frames

“…When proceeding to the analysis of capacity of the different components of the structure, a time function is needed to express the nonlinear behavior for elements as well as for materials [38][39][40][41][42][43]. Generally, the direct numerical integration of the dynamic equilibrium is the main approach to solve the dynamic response of structural systems at a discrete point with provided time [44][45][46][47][48][49][50]. The accelerograms used in this investigation are the horizontal components of the Imperial Valley-Holtville Post Office and Imperial Valley-EL Centro (Figure 10).…”

Analytical Study of the Seismic Performance of Steel-Braced Frames with Masonry Infill

“…The effect of brick infill walls on the seismic performance of eccentrically braced frames was studied by Daryan et al (2009). By using an explicit finite element method, they demonstrated that the presence of masonry infill can increase the elastic range of the forcedisplacement behaviour, while the plastic deformation capacity of the frame will be deteriorated due to fragility of the masonry wall.…”

“…By using an explicit finite element method, they demonstrated that the presence of masonry infill can increase the elastic range of the forcedisplacement behaviour, while the plastic deformation capacity of the frame will be deteriorated due to fragility of the masonry wall. However, the results of Daryan et al (2009) study were based on the superposition of two distinct experimental tests on a CBF and a masonry infill wall and, therefore, could not capture the actual frame-infill interaction. In a more recent study, Ahmady Jazany et al (2013) conducted a series of experimental tests to investigate the seismic performance of half-scale CBFs with masonry infill.…”

Influence of masonry infill on the seismic performance of concentrically braced frames

“…To obtain acceptable results, the effect of masonry infill should be considered in the calculation of the compressive capacity of the brace elements. Daryan et al [26] investigated the effect of infill brick walls on the seismic behaviour of eccentrically braced frames using an explicit finite element method. This study showed that, in general, the presence of masonry wall increases the yield strength and the elastic range of the forcedisplacement curves.…”