Document Type : Research Article
Authors
1
M.Sc Graduate of Structural Engineering, Department of Civil Engineering, Faculty of Engineering, Arak University, Arak, Iran
2
Associate Professor of Structural Engineering, Department of Civil Engineering, Faculty of Engineering, Arak University, Arak, Iran
Abstract
In recent years, interlocking mortarless masonry walls have been extensively implemented in different parts of the world as internal or external walls in buildings. Not only the interlocking system of these walls accelerates the speed of construction due to the self-aligning feature of bricks/blocks and the elimination of mortar layers but also reduces the need for skilled masons. These exceptional characteristics of interlocking walls have made them cost-effective and eco-friendly and led them to be a suitable replacement for typical masonry walls. Since the seismic performance of the interlocking systems has not been investigated sufficiently by researchers, studying and analyzing their behavior under seismic excitations is extremely vital for future construction. In this research, the seismic performance of an interlocking wall called “Putra” has been evaluated based on different approaches and using a 475-year return period earthquake spectrum of Standard 2800. Numerical three-dimensional micro-scale modeling has been utilized for accurate simulation of mortarless joints and interlocking blocks. After the validation process of numerical modeling in the ABAQUS finite element package, the in-plane load-carrying capacity of interlocking masonry walls subjected to combined vertical and lateral loadings has been conducted using nonlinear static analysis.
To consider the effect of different story levels, the amount of pre-compressive loads that are applied to masonry walls in different story levels of typical buildings has been considered as dead loads in the analyses (0.5 MPa for the first story, 0.25 MPa for the third story, and 0.1 MPa for the fourth story). The effective stiffness, ultimate strength, maximum displacement, dissipated energy, and ductility factor of the Putra interlocking wall under different vertical loads have been derived from bilinear graphs and discussed. Moreover, since the behavior factor of interlocking walls has not been evaluated in studies so far, the behavior factor of the Putra wall has been derived under different vertical loads for further calculations. Then, based on the Iranian seismic design code for non-structural components of buildings, the seismic performance of walls has been conducted using the elastic and inelastic spectra through the displacement-based and force-based methods. It was observed that according to the displacement-based method, 12 out of 24 cases were acceptable for construction, whereas according to the force-based method, 13 out of 24 cases were confirmed, and overall, only 8 cases got the acceptance for both methods. Results demonstrated that the seismic performance of interlocking mortarless walls strongly depends on the intensity of vertical load and inelastic response spectra. It also revealed that the interlocking Putra wall can be constructed in different seismic areas of Iran under 1 MPa pre-compressive stress. Since the 1 MPa vertical load is generally intense, it is recommended to use unreinforced Putra interlocking mortarless masonry walls in different story levels of a typical building (except the last story) in low seismicity areas of Iran. Additionally, the Putra interlocking walls can be constructed in different parts of Iran except in very-high seismic regions, provided that a three-story building has to be constructed on the story where the Putra interlocking walls have been situated. Totally, it is not recommended to use these walls in low-rise buildings; however, it seems that they can be utilized in lower stories of mid-rise buildings or in lower and middle stories of high-rise buildings.
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