# Retrofitting Masonry Walls against Out-Of-Plane Loading with Timber Based Panels
## 5 Conclusions  
In this paper, a three-stage numerical study, calibrated and validated through experimental data obtained from a three-phase experimental campaign conducted by the authors, is presented. This paper aims to numerically evaluate the capacity and effectiveness of a proposed timber-based retrofit technique against out-of-plane failure. After an introduction of the overall conceptualisation of the study and brief detail of the conducted experimental program, this paper focuses on the development and analysis of a 3D finite element computational model using ABAQUS FEA software. The first stage of the numerical analysis was the material characterisation, where a detailed micromodelling approach was employed to simulate the compression test on the masonry cubic (MC) specimen. The linear mechanical properties of the brick unit and mortar obtained directly from the compression test on the brick unit and mortar were used as the input parameter. For the nonlinear mechanical properties of the unit and mortar, the concrete damage plasticity (CDP) model available in ABAQUS was used to describe the constitutive material relations. To do this, the ductility index and fracture energy data available in many literature reports [27; 30; 31; 32; 33] were used. Thereafter, the brick-mortar interface was calibrated against the experimental data. The FE model developed was able to predict the behaviour and failure of the MC specimen with a difference of 5% between the numerical value and experimental value. Hence, the main finding from this phase was that the calibrated material properties for the unit and mortar joint used in the numerical simulation of the MC compression tests represented the approximate properties of the materials. After that, the properties were later used to analyse the out-of-plane response of small-scale and large-scale plain and retrofitted masonry wall in the subsequent phases. The numerical simulation of the four-point bending test for both the small-scale and large-scale test were also carried out to simulate the capacity and failure pattern of the masonry prism and wall tested in the laboratory. As highlighted in Section 4.2, the model strategy adopted for both masonry prism and wall was based on the detailed micromodel technique with the brick mortar interface precluded to avoid ABAQUS convergence issue because of too many contacts between the unit and mortar. Thus, the interface properties were lumped into the properties of the mortar, and new nonlinear properties of mortar were obtained and calibrated using the test results of the small-scale plain masonry prism. The properties of the brick units calibrated in the previous step were used. In addition, the damage constitutive model available in ABAQUS was used to define the nonlinear behaviour of OSB timber and incorporated together with pure elastic properties of the anchor connection for the creation of the retrofitted model. The analysis of the masonry prism/wall model under a continuous increase of load in the form of a load-displacement curve was obtained using the static RIKS method (arc-length control). The comparative analysis of the numerical results with the test results confirms that the FE models developed adequately captured the behaviour of both the plain and retrofitted model to the ultimate load. The models also show an excellent correlation of the compressive damage (DAMAGEC) and tensile damage (DAMAGET) with the experimental failure pattern. Generally, the model predicted the peak load and the corresponding failure, toughness and resilience to within less than 10% of the average test results. Numerically, this study contributed to the modelling of masonry walls retrofitted with OSB panels considering the mechanical properties of individual components, i.e., masonry unit, mortar and the retrofit materials (OSB timber and anchor connectors). Its application to simulate the behaviour of the retrofit system will facilitate laboratory experiments in studying further the efficiency of the proposed retrofit techniques.