Experimental and numerical study of behaviour of reinforced masonry walls with NSM CFRP strips subjected to combined loads

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry walls reinforced with NSM CFRP strips under combined shear-compression loads. Masonry walls have been tested under vertical compression, with different bed joint orientations 90ffi and 45ffi relative to the loading direction. Different reinforcement orientations were used including vertical, horizontal, and a combination of both sides of the wall. The second part of this paper comprises a numerical analysis of unreinforced brick masonry (URM) walls using the detailed micro-modelling approach (DMM) by means of ABAQUS software. In this analysis, the non-linearity behavior of brick and mortar was simulated using the concrete damaged plasticity (CDP) constitutive laws. The results proved that the application of the NSM-CFRP strips on the masonry wall influences significantly strength, ductility, and post-peak behavior, as well as changing the failure modes. The adopted DMM model provides a good interface to predict the post peak behavior and failure mode of unreinforced brick masonry walls.Peer reviewe

Etude Expérimentale et Numérique du Comportement des Murs en Maçonnerie Renforcés par Matériau Composite

There is a large number of old buildings including historical and cultural monuments around the world, which are constructed with unreinforced masonry (URM) and they are exposed to damage due to overloading and deterioration caused by environmental hazards. Therefore, it is highly recommended that adequate retrofit techniques be suggested in order to preserve this type of structure. Different techniques for the reinforcement of URM structures have been proposed, using a wide range of materials such as composite materials. Among the techniques used in the reinforcement of masonry structures, there is the Externally Bonded (EB) fiberreinforced polymer (FRP) technique and the Near-Surface Mounted (NSM) fiber-reinforced polymer (FRP) technique. The main objective of the current study was to investigate the shear behavior of FRP strengthened brick masonry assemblages under in-plane loading. For this purpose, four masonry specimen types were investigated. The obtained results show that, the strengthening techniques had a considerable improvement in shear strength and deformation capacity. In order to model the behaviour of masonry walls, the detailed micro-modelling (DMM) approach was adopted, which is implemented in ABAQUS program to perform a numeric simulation of different masonry assemblages. In this study, finite element models were developed to simulate the behavior of different test types of masonry assemblages. The nonlinearities behavior of brick and mortar was simulated using the Concrete Damaged Plasticity (CDP) constitutive laws. However, FRP strips were connected to masonry elements by interface model. This approach allows failure to occur on either the brick, mortar and brickmortar interface. In addition, the Extended Finite Element Method (XFEM)-based cohesive zone approach was used to simulate the arbitrary crack initiation and crack propagation within a mortar without an initial definition of crack location. The results of numerical simulations were compared with the experimental results. It was concluded that the proposed model presented an excellent prediction for shear behavior and failure mode of unreinforced and FRP-reinforced masonry walls. On the other hand, XFEM was found as a powerful technique to be used for the analysis of the fracture process and crack propagation in masonry wall

Experimental and Numerical Study of Behaviour of Reinforced Masonry Walls with NSM CFRP Strips Subjected to Combined Loads

Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry walls reinforced with NSM CFRP strips under combined shear-compression loads. Masonry walls have been tested under vertical compression, with different bed joint orientations 90° and 45° relative to the loading direction. Different reinforcement orientations were used including vertical, horizontal, and a combination of both sides of the wall. The second part of this paper comprises a numerical analysis of unreinforced brick masonry (URM) walls using the detailed micro-modelling approach (DMM) by means of ABAQUS software. In this analysis, the non-linearity behavior of brick and mortar was simulated using the concrete damaged plasticity (CDP) constitutive laws. The results proved that the application of the NSM-CFRP strips on the masonry wall influences significantly strength, ductility, and post-peak behavior, as well as changing the failure modes. The adopted DMM model provides a good interface to predict the post peak behavior and failure mode of unreinforced brick masonry walls

Experimental Research and Numerical Analysis of CFRP Retrofitted Masonry Triplets under Shear Loading

This paper presents an experimental and numerical study into the shear response of brick masonry triplet prisms under different levels of precompression, as well as samples reinforced with carbon fiber-reinforced polymer (CFRP) strips. Masonry triplets were constructed with two different mortar mix ratios (1:1:3 and 1:1:5). In this study, finite element models for the analysis of shear triplets are developed using detailed micro-modelling (DMM) approach and validated with the experimental data. The failure mechanisms observed in the masonry triplets were simulated using a coupled XFEM-cohesive behaviour approach in ABAQUS finite element software. The nonlinear behaviour of mortar and brick was simulated using the concrete damaged plasticity (CDP) constitutive laws. The cohesive element with zero thicknesses was employed to simulate the behaviour of the unit–mortar interfaces. The extended finite element method (XFEM) was employed to simulate the crack propagation in the mortar layer without an initial definition of crack location. CFRP strips were simulated by 3D shell elements and connected to masonry elements by an interface model. The changes in failure mechanism and shear strength are calculated for varying types of mortar and fiber orientation of CFRP composite. Based on this study, it was concluded that the ultimate shear strength of masonry triplets is increased due to the external bonding of CFRP strips. The performance of masonry specimens strengthened with CFRP strips is assessed in terms of gain in shear strength and post-peak behaviour for all configurations and types of mortar considered. The comparison of FE and experimental results proved that the models have the potential to be used in practice to accurately predict the shear strength and reflect damage progression in unreinforced and CFRP-reinforced masonry triplets under in-plane loading, including the debonding of the CFRP reinforcement. Additionally, XFEM was found to be a powerful technique to be used for the location of crack initiation and crack propagation in the mortar layer