International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2016): 79.57 | Impact Factor (2015): 6.391 Volume 7 Issue 1, January 2018 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Height-to-Length Ratio Effect on the Response of Unreinforced Masonry Wall Subjected to Vertical Load Using Detailed-Micro Modeling Approach Alaa H. Al-Zuhairi 1 , Ammar Rafid Ahmed 2 1, 2 Universityof Baghdad, Department of Civil Engineering, College of Engineering, Al-Jadriyah, Baghdad, Iraq Abstract: This paper aimed to investigate the effect of the height-to-length ratio of unreinforced masonry (URM) walls when loaded by a vertical load. The finite element (FE) method was implemented for modeling and analysis of URM wall. In this paper, ABAQUS, FE software with implicit solver was used to model and analysis URM walls subjected to a vertical load. In order to ensure the validity of Detailed Micro Model (DMM) in predicting the behavior of URM walls under vertical load, the results of the proposed model are compared with experimental results. Load-displacement relationship of the proposed numerical model is found of a good agreement with that of the published experimental results. Evidence shows that load-displacement curve obtained from the FE model has almost the same trend of experimental one. A case study of URM walls was conducted to investigate the influence of the wall aspect ratio on its capacity and stress distribution due to a vertical load using DMM approach. In this paper, curves obtained that show a relationship between height level and generated compressive stress of walls with different aspects ratios and the strength of each URM wall and the DMM technique that has been utilized for numerical simulation. Keywords: URM walls, Concrete masonry units, Detailed Micro Modeling (DMM), Aspect ratio, Stress distribution 1. Introduction Masonry as a material considered heterogeneous and composite that comprises of units and joints [2]. Due to its heterogeneous nature and nonlinear behavior, it is challenging to model and analyze masonry structures [11]. Although masonry material is ancient yet in today’s buildings it has been frequently employed. In the last years, a new development in the masonry materials and applications happened but the assembling methods of masonry units are essentially the same as the methods used many decades ago. Masonry materials, procedures, and applications happened through time as expected, impacted by the capital and local culture, tools knowledge and availability and materials and architectural reasons. Simplicity is the greatest advantage of masonry construction. Laying on top of each other pieces of stone or brick, either with or without adhesive mortar, is a simple, nonetheless appropriate method that has been successful ever since centuries. Additional important features are the strength, durability, low maintenance, flexibility, sound absorption and fire protection. Examples where structural masonry still is used are load-bearing walls, infill panels to resist wind loads and seismic, low-rise buildings and pre-stressed masonry cores [1]. Nonetheless, advanced applications of structural masonry are far behind due to the fact that masonry design rules have not kept up with the developments of concrete and steel. The design rules development delay essentially because of lack of insight and lack of models that explain the complex behavior of units, mortar joints, and masonry as a composite. Procedures of calculation that are presently available are basically of empirical and traditional and the tools used for numerical analysis and/or design of masonry structures is impartially primary [1]. At the present time, more complex numerical tools have been presented, that are able to predict the behavior of structure from the linear stage, during the course of cracking and degradation up to complete failure. This goal can be reached only through accurate and robust constitutive model implementation using advanced solution methods of equations system, which results from the finite element method. Detailed Micro-Modelling (DMM) method is a finite element new technique that deals separately with masonry units and mortar. Lourenco in 1995 was initially adopted the DMM method where the representation of masonry units and mortar joints is by continuum solid elements while the representation of unit-mortar interface is by discontinuous contact elements [1]. All the failure mechanisms of masonry must be included in the micro model, and they are, joints cracking, sliding over one head or bed joint, units cracking and masonry crushing [6]. A comprehensive micro model has to include all the failure mechanisms of masonry, viz., joints cracking, sliding over one head or bed joint, units cracking and masonry crushing [6]. In addition, the computer hardware evolutions recently allowed sophisticated analysis methods to be implemented, which allow the structures detailed modeling and the following behavior simulation while subjected to distinctive actions. However, advanced methods usage requires, generally, also a complicated characterization of the model, including viz. a detailed representation of the geometry and a huge number of material parameters [10]. 2. Modeling Strategy Masonry material exhibits distinct directional properties because of the mortar joints [5], which act as planes of weakness [6]. Generally, the approach for numerical representation depends on the level of accuracy and the level of simplicity preferred. The consideration of micro modeling approach is to describe the individual components of masonry, namely, units and mortar. There are two types of Paper ID: ART20179673 DOI: 10.21275/ART20179673 1456