## 1 Introduction
[PERSON] and [PERSON] [26] and [PERSON] et al. [27] investigated the dynamic performance of the brick masonry walls against blast loading. [PERSON] et al. [28] studied local and global damage to a reinforced masonry wall under the close-in explosion scenario. According to the results, instead of bending or shear failure of the wall, the close-in explosion caused local damage by punching [28]. [PERSON] et al. [29] reported the explosive resistance of a stone wall. [PERSON] and [PERSON] [30] and [PERSON] et al. [31] investigated failure patterns of masonry walls through real blast loading tests. [PERSON] et al. [32] applied 3D finite element models to simulate the out-of-plane behavior of un-reinforced masonry walls constructed with bricks under static and dynamic loadings. According to ASCE 51-11 [33], the fragmentation of building elements and thrown fireballs have the most dangerous impact in an explosion event. Strengthening methods to prevent the destructive effects of explosions have been an area of interest for some researchers. The most common explosives strengthening techniques in masonry walls include the use of fiber-reinforced polymers (FRP), polyurea, and polyurethane coatings, using steel sheets, aluminum foam, and engineered cementitious composites [34; 35; 36; 37; 38; 39; 40; 41]. Previous studies on the behavior of AAC materials under blast loads are limited. In particular, studies investigating the effect of blast loads on structural elements made with AAC are scarce. [PERSON] et al. [42] numerically modeled infilled walls constructed with AAC blocks under gas explosion in LS-DYNA. [PERSON] et al. [43] investigated the performance of an autoclaved masonry wall under methane explosion. This study was performed using field tests and numerical simulations [43]. In an experimental study, [PERSON] et al. [44] evaluated retrofitted masonry walls consisting of clay bricks and autoclaved aerated concrete blocks under explosion. They used polyurea layers to increase the explosion resistance of the considered walls [44]. In addition, [PERSON] et al. [45] studied the effect of high strain loading conditions on the properties of AAC materials. [PERSON] et al. [46] determined the ballistic resistance of AAC against projectile penetration. AAC lightweight concrete blocks are considered among the first alternatives in construction, especially in the reconstruction of urban areas damaged in the Middle East wars. There is a knowledge gap in the assessment methods and priorities of masonry components [47]. This matter is even more notable in the building constructions with AAC units. Since very few studies have been performed in this field so far, the material properties of autoclaved aerated concrete are not comprehensively known, especially under severe loading conditions. Therefore, investigation of the behavior of building elements constructed with AAC units under blast loading seems necessary. Understanding the behavior of these blocks under explosion and providing solutions to increase their explosive capacity can be an interesting topic for researchers in this field. The present study aimed to identify, investigate, and analyze the behavior of masonry walls made of AAC lightweight concrete units under the effect of blast loading. The crack growth, displacements, stress distribution, and energy absorption of different models of this type of wall were investigated using FE modeling in the ABAQUS/Explicit package. The main goal of this study was to implement an effective FE procedure in the analysis of masonry models under lateral blast pressure considering different wall thicknesses, since the autoclaved aerated concrete units can be produced with various dimensions.