Browsing by Author "Kipcak, Firat"

Now showing 1 - 6 of 6

Effect of Adobe Wall Shapes and Openings on Out-Of Behavior
(Elsevier Science inc, 2025) Kipcak, Firat; Erdil, Baris
Adobe masonry structures which are among the traditional structures, are affected by many parameters like other masonry structures. These parameters include material, workmanship, mortar, support condition, wall direction, wall slenderness and opening properties. Those parameters are important because they affect the seismic performance significantly. There are many studies in the literature considering the in-plane behavior of masonry walls; however, it has been observed after many earthquakes that most of the adobe walls collapse due to out-of-plane displacements. In order to understand the out-of-plane behavior well, this study aims to experimentally and numerically investigate the out-of-plane behavior of adobe walls having different configurations such as wall aspect ratio, wall shape and openings. The failure mechanisms, horizontal load capacity ratios and failure profiles were evaluated. In the study, a total of 18 different wall models were produced: 6 U-shaped walls with two-side support walls, 6 L-shaped walls with one-side support walls and 6 I-shaped walls without support walls. All the walls were tested on a tilting table. They were also analyzed by simplified micro modeling technique in ABAQUS software. The adobe walls were constructed in the form of interlocking pattern according to the traditional pattern. A clay and fiber mixed mortar with the same properties as the unit was used between the adobe units. According to the experimental and numerical results, it was observed that the support walls in adobe walls increased the out-of-plane wall stiffness and lateral load capacity ratio. As the wall aspect ratio increased, the lateral load capacity decreased in the models with support walls and increased in the models without support walls. Increasing wall length decreased the effectiveness of the supporting wall. Door/window openings left in the wall did not adversely affect the capacity to a great extent. The lateral load capacity/weight ratio changed slightly due to the weight reduction of the openings. The capacities and failure mechanisms obtained from the experimental and numerical studies were found to be similar.
The Effect of Voids on Flexural Capacity of Reinforced Concrete Slabs
(Budapest Univ Technology Economics, 2023) Kipcak, Firat; Erdil, Baris; Tapan, Mucip; Karasin, Abdulhalim
The voided reinforced concrete slab system is mainly produced with polyester foam placed mostly at the bottom of the slab. The aim of the voids is to reduce the weight of the slab. In this paper behavior of the voided reinforced concrete slabs in which voids placed at the mid-height of the slab cross-section, is examined analytically. A series of models were created to come up with a lightweight slab. Two distinct slab models were analyzed using the ABAQUS software. In the first group, slabs had three layers, in which bottom and top layers were of solid reinforced concrete, but the mid layer was of voided unreinforced concrete. In the second layer, in order to increase the contact between top and bottom layers of the slab, crossties were utilized, and the mid layer was reinforced accordingly. Since all the layers were 5 cm thick, the total thickness of the slabs were 15 cm. Slabs were 100 cm wide and 200 cm long. They were simulated the three-point bending test. Concrete damaged plasticity material model (CDPM) for concrete and elastoplastic material model for steel was selected. From the results it was found that moment capacity decreased with the increase in the volume of the voids. There was a sudden decrease in strength after reaching the yield strength in voided slab without a crosstie. In addition, crossties enabled the reduction of the weight of the slabs without significant decrease in moment capacity.
Experimental and Numerical Investigation of Out-Of Behavior of Masonry Brick Walls With Low-Strength Mortar: Effects of Slenderness, Shape and Openings
(Taylor & Francis Inc, 2025) Kipcak, Firat; Erdil, Baris; Tapan, Mucip
Masonry structures are traditional buildings made up of heterogeneous and anisotropic components, which create various challenges in design, construction and analysis. This study aims at investigating the out-of-plane behavior of walls constructed with low-strength mortar through both experimental and numerical approaches. In this context, the effects of wall slenderness, shape and openings on out-of-plane behavior were explored. Different wall slenderness ratios (height/length) and door/window openings were considered in the wall models. Masonry wall models were experimentally tested on a tilting table and further analyzed using ABAQUS software. Six wall models each of U, L and I shapes with two-side, one-side and no support respectively were constructed. Each model was tested at least twice and experimental and analysis results were compared. The results showed that increasing wall slenderness (from 1.33 to 2) led to 10-50% reductions in lateral load capacity, especially in U-shaped walls. More door and window openings further decreased capacity and enlarged failure zones. A single supporting wall increased capacity by 3.5 times, while two supports raised it 5.5 times. More ductile behavior was observed due to the supporting walls, which prevented early collapse. The findings emphasize the critical role of support walls in reducing capacity losses.
Investigation of Flexural Behavior of Voided and Crosstie Reinforced Slabs
(Wiley, 2025) Kipcak, Firat; Tapan, Mucip; Erdil, Baris; Karasin, Abdulhalim
Reinforced concrete slabs constitute a significant portion of the building weight. One of the methods developed to reduce the slab weight is the voided slab system. In this system, voids are formed with materials such as plastic or foam. In this study, voided slabs with concrete connections, which are rarely found in the literature, were investigated. Because there is no sufficient study regarding the bending capacity and behavior of voided slabs, 11 slabs with varying void ratios and crosstie reinforcement were tested to fill this gap. In this context, three solid slabs without voids and eight slabs with different void ratios were produced. Polystyrene foam was used to create three equal layers. The top and bottom layers are reinforced concrete, and the middle layer consists of square concrete connections and polystyrene foam, which has not been studied yet. The slabs were divided into two groups: the first group specimens had no crossties, whereas the second group had varying crossties. In this context, it was tried to determine the optimum weight and performance of the slab. A uniformly distributed load was applied using the three-point bending method. According to the results, the slab weakened with the use of polystyrene foams, and the ultimate load capacity decreased accordingly. The stiffness, ductility, toughness, and load capacity of solid slabs were found to be higher than those of voided slabs. When the void ratio was 20%, the failure mode changed from flexure to shear. By using crosstie reinforcement, shear failure was prevented, and ductile behavior was increased. Finally, the load capacity of the slabs was compared with ACI318-19 and other studies, and a new equation was proposed.
Numerical Study of the Out-Of Response of Dry-Stack Double-Wythe Brick Walls With Header Bricks
(MDPI, 2025) Kipcak, Firat
Walls in masonry structures exhibit sensitive behavior under out-of-plane displacements. Although numerous studies address in-plane behavior, research focusing on out-of-plane response remains limited. The performance of masonry walls is influenced by several factors, including material characteristics, construction defects, mortar quality, support conditions, wall slenderness, and the properties of openings. Because of those parameters, detailed experimental and numerical studies are required to understand the behavior. Double- or multi-wythe masonry is commonly used, and header (or through) bricks are often placed to ensure interlocking between the wythes. The number and arrangement of the header bricks directly influence the wall behavior. Particularly after recent earthquakes, significant damage has been observed in multi-wythe walls, and the role of header bricks in wall performance is not yet fully understood. This study investigates the out-of-plane behavior of double-wythe, two-sided brick walls, in which header bricks are used only in the out-of-plane direction. Numerical analyses were performed on eight different wall models. In these models, header bricks with varying quantities and arrangements were placed perpendicular to the wythes. Lateral load analyses were conducted using the finite element method and micro-modeling technique implemented in ABAQUS software (Version 2022). Two models were validated using the referenced experimental results. The findings indicate that all walls that incorporate header brick exhibit higher lateral capacities. When compared to the reference wall model, the load-to-weight ratio increased with the increase in the number of header bricks. The lateral capacity ratio increased by factors of 1.29, 1.50, 1.68, and 1.81 in walls containing one, two, three, and four vertical rows of header bricks, respectively. When the header bricks were distributed uniformly throughout the wall, the capacity increased by a factor of 1.61. These results demonstrate that the header brick pattern also affects the wall capacity. Additionally, the presence of header bricks directly influences the failure mechanism of the wall.
Out-Of Behavior of Dry-Stack Brick Masonry Walls
(Wiley, 2024) Erdil, Baris; Kipcak, Firat; Tapan, Muecip
As a result of the combination of the complex behavior of masonry buildings with insufficient material quality and lack in engineering calculations, a large number of damages has been observed in the earthquakes that occurred in recent years. Therefore, a realistic understanding of the behavior of masonry walls and buildings is necessary to construct seismic-resistant structures. Since masonry walls have many variables, performing experiments in which each variable is present at the same time will make it difficult to understand the behavior. For these reasons, considering the out-of-plane failures that are frequently mentioned in recent earthquakes, in this study, variables in dry-stack brick masonry buildings such as the aspect ratio of the wall (2, 1.33, and 1), the presence of the transverse walls (2, 1, and 0), and the openings in the walls (door and/or window) were taken into account separately. Eighteen different wall configurations were designed, and a total of 48 dry-stack walls having U-shape, L-shape, and I-shape in plan were tested by a specially constructed tilting table setup to determine their out-of-plane behavior. From the test results, it was found that lateral load capacity of the U-shaped walls without openings increased as the aspect ratio (L/H) decreased. No change in capacity was observed in L- and I-shaped walls when the aspect ratio was reduced from 2 to 1. Door and/or window openings were found to affect only the L-shaped walls. In addition, it was determined that failure patterns were affected from the aspect ratio and the presence of the openings.