Behavior Of Masonry Walls Research Articles

Cyclic behavior of masonry walls strengthened by tie rods

This preliminary work is aimed at investigating numerically the behaviour of unreinforced masonry walls strengthened through the use of metallic tie rods. In the first part, the improvement of strength is studied by evaluating the increase in shear resistance for low vertical action values, which is the most critical state for unreinforced masonry. Tie rods are placed along diagonals of the walls, as to maximize their effect on the overall strength and on recentering capabilities of piers. Subsequently, by using non-linear dynamic analyses carried out on a masonry wall, the importance of the axial forces acting on retrofitted piers during a seismic event is highlighted. It is shown that this becomes particularly important in the presence of a significant vertical component due to seismic actions. All the analyses are carried-out with non-linear material models, as to investigate the capacity in post-elastic field. Finally, the recentering capabilities and cyclic response of strengthened piers using tie rods are evaluated, on the basis of the residual transversal displacements measured at the end of numerical simulations. Results show improvements on the shear-displacements cyclic behaviour of reinforced piers, including better recentering capabilities, enhancing masonry performance under seismic conditions.

Assessment of the effect of FRCM materials on the behaviour of masonry walls by means of FE models

Several experimental tests recently performed on tuff or clay brick masonry elements (i.e. walls and arches) demonstrated the benefits of Fiber Reinforced Cementitious Matrix (FRCM) systems used as externally bonded reinforcement for strengthening and seismic retrofitting of masonry structures. Tensile tests on coupons made of different FRCM materials allowed defining constitutive laws in tension, which are characterized by a post-cracking behaviour with more or less effective tension stiffening effect.This paper is focussed on the assessment of the influence of the mechanical properties of both the masonry substrate and the FRCM systems on the overall behaviour of strengthened masonry walls subjected to diagonal compression. To this aim, several numerical analyses were carried out for simulating diagonal compression tests by means of a bi-dimensional Finite Element Model. A non-linear behaviour was assumed for both masonry substrates and FRCM reinforcements. For the latter ones, a perfect bond condition was assumed and the tension stiffening effect of the mortar was taken into account in the tensile behaviour of the FRCM reinforcement based on experimental results previously carried out by the Authors.

Finite element modeling of masonry wall with mortar 1pc : 4 lime : 10 sand under lateral force

This paper gives a detailed presentation of three-dimensional Finite Element Model that has been constructed for Masonry Wall under lateral force by using Abaqus software. This research aimed to investigate the behavior of Masonry Walls under lateral force and developed load-displacement curve. From the result that The numerical model using the Abaqus Software can represent the load-displacement curve of Masonry Walls due to lateral forces, Numerical Results with the Abaqus Software obtained that the magnitude of the load on condition of Plastic is 82.13 KN and experimental results obtained of 81 KN. There is a difference of 1.4%, Based on Abaqus Software with Numerical results obtained a compressive strength of masonry wall fm = 1.8 MPa with a modulus of elasticity = 150 MPa, Calculation of the natural frequency of structures with Abaqus Software is obtained as the difference of 2.13-2.92% with the test results Hakas (2017)

Element Modeling of Masonry Wall With Opening Under Lateral Force

Abstract: Three-dimensional Finite Element Model for Masonry Wall with openings under lateral force using ABAQUS software. Finite element model verification with an experiment masonry wall in the laboratory without openings. The load-displacement relationship of finite element model is well agreed with experimental results. Parametric studies conducted on masonry wall with openings to investigate the influence of an area of openings. This research aimed to investigate the behavior of Masonry Walls with openings under lateral force. The result showed that the increase of the area of openings decreases stiffness and strength of masonry. It is also well observed from the result that lateral resistance of masonry will decrease for each area of the opening wall.

In-plane shear behavior of masonry walls strengthened with steel fiber-reinforced concrete overlay

Masonry load-bearing walls in unreinforced masonry (URM) buildings are the major load-resisting elements. The traditional URM buildings have shown poor performance during earthquakes which may be due to lack of lateral strength to withstand the inertia forces. Various retrofitting techniques have been proposed to improve the in-plane behavior of the existing URM walls. In recent proposed retrofitting techniques, innovative construction materials such as steel fiber-reinforced concrete (SFRC) have been employed in the form of a strengthening surface layer on URM walls. Experimental studies on this retrofitting technique which are mostly carried out on masonry panels indicate that this method is practical and efficient for seismic upgrading of URM walls. Therefore, to evaluate the effects of some parameters such as surface layer thickness, retrofitted face of the wall, wall aspect ratio, URM wall strength, and fiber content of SFRC mix on the in-plane shear behavior of both solid walls and walls with openings strengthened with SFRC overlay, a study is conducted through 3D finite-element modeling using software ABAQUS with appropriate material models. The analysis results indicate that in-plane strength enhancement of the retrofitted wall depends on wall aspect ratio. Furthermore, the surface layer thickness and fiber content of the SFRC mix have significant influence on the ultimate in-plane capacity of the walls retrofitted with SFRC surface layer. In addition, the efficiency of this strengthening technique in walls with opening depends on configuration of the surface layer on the walls. Finally, interaction of the masonry wall and SFRC overlay was evaluated through comparing the retrofitted walls’ in-plane strength with in-plane capacity of masonry and SFRC layer.

Modelling the out-of-plane behaviour of masonry walls retrofitted with engineered cementitious composites

The out-of-plane behaviour of masonry infill walls retrofitted using engineered cementitious composites (ECC) is investigated numerically in this paper. The behaviour of beam-like masonry specimens, considered to provide a simplistic representation of masonry infill walls, subjected to static four-point bending testing is investigated numerically through the use of nonlinear finite element analysis. The specimens are strengthened using a thin layer of ECC which is fully or partially bonded to their lower face (acting in tension). The numerical predictions obtained are validated against relevant test data and are used to provide insight into the mechanics through which the ECC layer enhances the out-of-plane behaviour of the subject specimens in terms of strength, stiffness and deflection. It was found that the specimens retrofitted with a partially bonded ECC layer exhibit more ductile behaviour (deflection) compared to those retrofitted with a fully-bonded ECC layer (the latter exhibiting higher load-carrying capacities). Finally, the validated models are employed to carry out a parametric study to investigate the effect of different design parameters, associated mainly with the properties of the materials used, on the behaviour of the specimens considered.

Experimental study of the in-plane cyclic behaviour of masonry walls strengthened by composite materials

This study presents the results of an experimental campaign on masonry walls to characterize their behaviour under in-plane solicitations. A series of five walls has been built, including one reference wall and four walls reinforced with externally bonded composites that are either FRP-composites (fibre reinforced polymer) or TRC-composites (textile reinforced mortar). In the present work, strengthening materials were not applied over the entire masonry surface: walls were reinforced only with vertical composite sheets, spaced to reduce the amount of composite materials used for the reinforcement. Each wall was tested under a vertical compression load and cyclic reversed horizontal displacements until failure. This article presents the results in terms of load displacement curves, analyses the damage and failure modes of the different walls and provides a comparative study based on performance parameters, such as load capacity, ductility, stiffness degradation, energy dissipation capacity to highlight advantages and limitations of the different strengthening materials.

Shape effect of interlocking brocks on force-displacement relationship and failure behavior of masonry walls

Shape effect of interlocking brocks on force-displacement relationship and failure behavior of masonry walls

Improvement of Out-of-Plane Behavior of Masonry Walls Using FRP Fibers

Improvement of Out-of-Plane Behavior of Masonry Walls Using FRP Fibers

Behaviour of Masonry Walls under Horizontal Shear in Mining Areas

The paper discusses behaviour of masonry walls constructed with small-sized elements under the effects of mining activity. It presents some mechanisms of damage occurring in such structures, its forms in real life and the behaviour of large fragments of masonry walls subjected to specific loads in FEM computational models. It offers a constitutive material model, which enables numerical analyses and monitoring of the behaviour of numerical models as regards elastic-plastic performance of the material, with consideration of its degradation. Results from the numerical analyses are discussed for isolated fragments of the wall subjected to horizontal shear, with consideration of degradation, impact of imposed vertical load as well as the effect of weakening of the wall, which was achieved by introducing openings in it, on the performance and deformation of the wall.

Two-way bending behaviour of hollow concrete block masonry walls reinforced by composite materials

Abstract This paper presents an experimental study devoted to investigating the effectiveness of externally bonded composites to improve the out-of-plane behaviour of masonry walls. Two strengthening materials were used that were chosen deliberately from more environmentally friendly composites: a flax fibre reinforced polymer and a glass textile reinforced cementitious matrix. Five masonry walls were tested under two-way bending: one reference, three reinforced and one repaired. Special attention was paid to the anchorage of the strengthening bands to the masonry. The performance of each strengthening configuration was estimated by considering the out-of-plane load capacity, ductility, energy dissipation and crack pattern. It appears that all of the tested specimens, whatever the strengthening materials, developed a substantial increase (from 20% to 30%) in their out-of-plane load capacity and exhibited ductility and displacement capacity. The transversal anchor systems proved to be effective (and readily achievable). From the results obtained in this study, it is concluded that the multiple matrix cracks in the glass textile-reinforced mortar allow a more extensive stress redistribution that makes this material a promising solution for the out-of-plane strengthening of masonry walls. An analytical approach, based on a cross-section analysis, is introduced to calculate the load-carrying capacity of the strengthened walls and a satisfactory agreement is obtained between experimental and theoretical results.

Experimental observations on the in-plane behaviour of masonry wall infilled RC frames; focusing on deformation limits and backbone curve

The ratio of frame strength and stiffness to masonry infill are major parameters that influence the seismic capacity of masonry infill. The influence of such parameters to seismic capacity in terms of strength, stiffness and deformation has significant variations between different design codes and past literature on the topic. This study focused on the in-plane behaviour of unreinforced masonry infill walls installed in reinforced concrete (RC) frames with different strengths. In the first part of this study, two ½ scale specimens with different RC frames and identical masonry infill walls were tested using a static cyclic loading protocol. The main objective was investigating the influence of changing frame strength to seismic capacity in terms of: strength, stiffness and deformation. Results of the presented experiment showed that as the ratio of frame shear strength to masonry shear strength increased, there was great improvement of the masonry infill walls in terms of strength and avoidance of sudden brittle behaviour of the masonry infill. However, varying frame strength did not significantly influence the initial stiffness and story drift at maximum strength. In the second part of this study, an investigation was conducted on the deformation limits of masonry infilled RC frames and the influence of various parameters, based on data collected from many recent experimental tests. Based on these experimental results, the deformation limits of masonry infill were found to be directly proportional to both the compressive prism strength of the masonry infill and the ratio of shear strength of frame to that of the masonry infill. The influence of aspect ratio showed large variation and it is difficult to conclude its level of influence on deformation. A simplified procedure based on experimental data was proposed that can estimate the backbone curve and gave good estimation of the post-peak lateral strength degradation slope based on the ratio of frame strength with simple hand calculation. Such a method is useful in the preliminary design process to help practicing engineers understand the general behaviour expected by infilled RC frames.

Numerical and Experimental Validation of a 3D Macro-Model for the In-Plane and Out-Of-Plane Behavior of Unreinforced Masonry Walls

ABSTRACTThe behavior of historical UnReinforced Masonry (URM) buildings subjected to earthquake loading is usually governed by a complex interaction between the in-plane and out-of-plane response of masonry walls. In modern masonry building, the in-plane behavior of masonry walls is generally guaranteed in the structural design, but thin non-structural masonry infills are often vulnerable to out-of-plane actions. A reliable prediction of the combined in-plane and out-of-plane behavior of URM walls requires rigorous nonlinear finite element models, whose complexity and computational cost are generally unsuitable for current engineering applications, motivating the research of alternative numerical approaches. This article presents a study for validation of a 3D macro-model intended to simulate the combined in-plane and out-of-plane behavior of unreinforced masonry walls, against experimental results available in the literature and FEM simulations. The model is based on a three-dimensional macro-element whose kinematics is governed by seven degrees of freedom only. The mechanical behavior of the element is based on a fiber discretization approach that adopts basic material parameters. The performance of the proposed macro-element strategy is assessed by means of nonlinear static analyses performed on masonry walls, for which both numerical and experimental results are available in the literature.

Numerical model for nonlinear analysis of masonry walls

A new proposal to represent the in-plane non-linear structural behavior of masonry walls is presented. The proposal has the ability to represent unreinforced, reinforced and confined masonry, considering different configurations. The wall configurations can take into account different dimensions for the wall and sizes for bricks and joints. Additionally, the model is able to consider different bricks, mortar and interface brick-mortar material properties. The most important point in the proposal is the implementation of the joint model. The joint model is defined as a special connection considering two non-linear springs (one longitudinal and one transversal to the joint connected in parallel) and one contact element (connected in series with the springs). This configuration is able to simulate almost all the failure possibilities in the joint. The bricks are implemented considering solid finite elements, taking into account a non-linear material behaviour. The main result of the model implemented in ANSYS is the capacity curve of the wall (top displacement versus base shear). The model was used to simulate the structural behaviour of a group of walls previously tested in laboratory at the University of La Serena and the University of Chile. The results obtained with the proposed model have a good agreement with those obtained in the laboratory tests.

Experimental response of historic brick masonry under biaxial loading

Unreinforced masonry (URM) structures in seismic areas are usually considered weak in terms of supporting dynamic action. Sufficient regularity of structural organisms plays an important part in fostering adequate behaviour of masonry building although the response of historic-URM (HURM) is greatly influenced by the strength of brick and mortar materials. The analysis of damaged masonry structures following an earthquake puts emphasis on knowing the proper values of strength under biaxial in-plane loading to estimate the response of HURM. On the other hand, damage to masonry buildings subjected to the last earthquakes in Italy (2016–17) which invested mainly its central regions, highlighted the need to further investigate HURM present in many small Italian towns to define the actual behaviour of masonry walls. This paper describes and discusses the results of an extensive experimental research campaign, developed over several years, on wallets, triplets, and walls built with solid historic bricks in 1/3rd scale. Additional experimental tests reported in this paper provide data useful to calibrate failure criteria available for assessing HURM buildings by numerical modelling using FE codes.

Numerical investigation of lateral earth pressure for unreinforced masonry walls

AbstractFor the design of unreinforced masonry walls under lateral earth pressure according to DIN EN 1996‐3 [1], the active earth pressure is used, which is less than the earth pressure at rest. For the consideration of active earth pressure, a sufficient deflection of the wall is needed. It is unknown whether the deflections in reality are large enough to justify a reduction of the active earth pressure. Therefore a numerical model has been developed which considers the load‐bearing behaviour of masonry walls, with several boundary conditions being considered to estimate the effective earth pressure.

Shear capacity estimation of fully grouted reinforced concrete masonry walls using neural network and adaptive neuro-fuzzy inference system models

In recent years, fully grouted reinforced concrete block masonry shear walls have been widely used as key structural elements for seismic resistance in medium- and high-rise buildings. However, accurately estimating their shear strength is truly challenging owing to the complex behavior of masonry walls under in-plane loads. This paper proposes the application of artificial neural network and adaptive neuro-fuzzy inference system models for predicting the shear strength of grouted reinforced concrete block masonry walls. To construct these models, an experiment was conducted and additional experimental data were gathered from published literature. Eleven main parameters were considered to be input parameters: compressive strength of grouted concrete block masonry, wall height, wall length, wall thickness, effective wall length, axial load, longitudinal and transverse reinforcement ratios, horizontal reinforcement spacing, and yield strength of longitudinal and transverse reinforcements. The prediction values of the well-trained artificial neural network and adaptive neuro-fuzzy inference system models agreed well with the experimental data. In addition, the comparison results showed that the two proposed models perform better than the existing empirical models. Therefore, they can be considered accurate and reliable models for estimating the shear strength of grouted reinforced concrete block masonry walls.

Effectiveness of FRCM Reinforcement Applied to Masonry Walls Subject to Axial Force and Out-Of-Plane Loads Evaluated by Experimental and Numerical Studies

ABSTRACTAn experimental campaign and a numerical analysis devoted to the investigation of the out-of-plane behavior of masonry walls reinforced with Fiber Reinforced Cementitious Matrix (FRCM) are presented here. The main goal of this study is to analyze and evaluate the effectiveness of the strengthening system, by discussing failure modes and capacity of strengthened masonry walls, in order to assess their behavior under out-of-plane horizontal actions, such as, for example, seismic actions. A purposely designed experimental set-up, able to separately and independently apply an axial force and out-of-plane horizontal actions on masonry walls, was used. Experimental results are discussed and compared with the outcomes of nonlinear analyses performed on simplified finite element models of the walls. A proper evaluation of the flexural capacity of FRCM strengthened walls is the first step of the ongoing process of drawing reliable code guidelines leading to a safe design of strengthened masonry structures.

Criteria for the Repair of Damage to Masonry Walls of Buildings Affected by Earthquakes Using Composite Materials with Inorganic Matrix

After the inspections to the damage caused by the last earthquake in Ecuador, and considering the construction typologies of reinforced concrete buildings in Guayaquil and Manta (Ecuador), in order to rebuild or repair the masonry walls we must resort to composite materials with inorganic matrix (cementitious). Composite materials in FRP with an organic matrix (epoxy) are not appropriate because, with an increase of strength they have a brittle behavior, therefore without possibility of energy dissipation not having the ductility provided by a metallic mesh or cobalt-metallic mesh, which have the advantage of using it with a cementitious matrix of frequent use in the current technology. Since the photographic records and the design of those masonry structures allow determining in detail the dynamics of the damage, it is possible to add to the theoretical analysis an experimental verification on the behavior of masonry walls with reinforced plastering with FRP or with metallic mesh with inorganic matrix under seismic actions.

Out-of-Plane Strengthening of Masonry Walls with FRCM Composite Materials

Structural strengthening by using composite materials proved to be one of the most suitable solutions for reinforcing masonry buildings. In this framework, the focus point of the presented experimental study is to evaluate the out-of-plane behaviour of masonry walls strengthened with Fiber Reinforced Cementitious Matrix (FRCM) composites when subjected to horizontal actions, by analyzing and discussing failure modes and their out-of-plane capacity. To this purpose, a new experimental set-up was developed, capable of applying an axial force and out-of-plane horizontal actions on full-scale masonry panels, placed in vertical position and subjected to a stress state similar to that present on a real masonry wall. Experimental results, obtained by using traditional and innovative techniques (such as Digital Image Correlation), will be compared with those coming from more conventional tensile and bond tests performed on FRCM coupons applied on masonry substrates, making use of simple theoretical models.