Vertically perforated clay bricks with enhanced structural performance through void geometry optimization

Abstract

The invention relates to hollow clay bricks designs having improved structural performance by developing alternative hollow geometries for traditional bricks in order to increase resistance against earthquakes and other external loads in masonry structures.

Description

[0001] VERTICALLY PERFORATED CLAY BRICKS WITH ENHANCED STRUCTURAL PERFORMANCE THROUGH VOID GEOMETRY OPTIMIZATION

[0002] Technical Field

[0003] The invention relates to perforated clay bricks with improved structural performance through the development of hollow geometries alternative to existing brick designs, for the purpose of increasing resistance against earthquakes and other external loads in masonry structures.

[0004] Prior Art

[0005] Masonry structures are a structural system widely preferred in traditional construction methods. This structural system, which is also frequently preferred stands out with advantages such as the easy accessibility of local materials and durability. The hollow bricks used in these structures reduce the overall weight of the structure while simultaneously improving its thermal and acoustic performance. However, masonry structures are inherently quite vulnerable to earthquakes. The severe damage sustained by such structures in high seismic risk zones demonstrates the importance of increasing the resistance of the structures against lateral forces.

[0006] Load-bearing masonry clay brick is a type of brick generally produced with vertical perforations, possessing higher strength compared to other brick types, and is capable of being used as a load-bearing element in structures that do not have a reinforced concrete load-bearing system. This type of brick, which is especially preferred in masonry buildings where the load-bearing system consists solely of walls, is also frequently preferred in the construction of intermediate partitions of factory walls and garden walls. These types of bricks, generally produced in withdimensions of 19 cm x 29 cm x 13.5 cm, weigh approximately 4500 g, and are used to construct walls with a thickness of 19 cm.

[0007] Studies in the literature optimizing the void geometry of masonry structures have focused solely on improving the thermal and acoustic insulation properties of these types of bricks; however, no study has been conducted aimed at increasing structural strength through void geometry.

[0008] In patent document CN203583752U, different designs are presented for bricks of various shapes with different geometries, solely for the purpose of improving handling ease from an ergonomic perspective. No calculation or design regarding structural strength has been performed. No intellectual property has been found other than this document.

[0009] Upon examination of the studies in the prior art, a need has arisen for the development of vertically perforated clay bricks with improved structural performance by developing alternative void geometries in order to increase earthquake resistance in masonry structures.

[0010] Objectives and Brief Desciption of the Invention

[0011] The object of the present invention is to develop new vertically perforated masonry clay bricks with improved structural performance by developing alternative hollow geometries for the purpose of increasing earthquake resistance in masonry structures.

[0012] Another object of the invention is to develop vertically perforated clay bricks that provide a certain level of increase in structural performance parameters such as lateral load capacity, energy dissipation, and ductility in structures to be produced with internal vertically perforated clay bricks, without performing any extra strengthening work.The developed new perforated brick designs can be easily integrated into existing production processes. Production can be carried out by merely changing the mold headers without requiring extra raw materials or costs. This demonstrates that the new designs are advantageous in terms of economy and application.

[0013] Detailed Description of the Invention

[0014] The embodiments developed to reach the objects of the invention are shown in the attached figures, in which;

[0015] Figure 1: A schematic view of two vertically hollow brickscurrently in use (prior art).

[0016] Figure 2: A view illustrating the directions in the numerical analyses performed within the scope of the invention.

[0017] Figure 3: Cross-sectional views of the alternative building bricks having different hollow geometries developed within the scope of the invention.

[0018] Figure 4: Cross-sectional views of bricks having different arch geometries.

[0019] Figure 5: Comparative graphs of the brick designs No. 11 and No. 13 (bricks of the subject invention) showing the best performance, against the currently used reference designs (Load-displacement curves for loading in 3 directions).

[0020] Figure 6: Detailed technical drawings of the finally developed bricks No. 11 and No. 13.

[0021] Reference numbers:

[0022] 1: Cross-sectional view of the Reference-1 brick

[0023] 2: Cross-sectional view of the Reference-2 brick3 : Loading in X direction (Out-of-plane)

[0024] 4: Loading in Y direction (In-plane)

[0025] 5: Loading in Y direction (Vertical load)

[0026] 6: Brick design with an h / w ratio of 0.42

[0027] 7: Brick design with an h / w ratio of 0.56

[0028] 8: Brick design with an h / w ratio of 0.85

[0029] 9: A rectangular body

[0030] 10: Beam / truss system element

[0031] 11 : Arched structure

[0032] Perforated masonry building bricks with improved structural performance through the development of alternative void geometries for the purpose of increasing resistance against earthquake and other external loads in masonry structures, characterized in that it comprises;

[0033] a rectangular body (9),

[0034] - beam and / or truss system elements (10) having different lengths in horizontal and vertical directions, formed within the body (9),

[0035] arched structures (11) formed by establishing connections on the beams located near the side surfaces of the body (9).

[0036] In the calculation, design, and analysis of the innovative masonry building bricks subject to the invention, the following steps were followed;

[0037] Modeling of the clay -based fired brick material,- Modeling of traditional perforated masonry building bricks using the finite element method (FEM),

[0038] - Realization of the developed alternative void geometry designs and optimum designs,

[0039] Investigation of the effects of Arch Geometry (H / W Ratio) on the structural behavior,

[0040] Validation of the numerical analyses performed for traditional brick samples,

[0041] - Execution of comparison and evaluation processes.

[0042] Since the clay-based fired brick material exhibits non-linear behaviors and plastic deformations under compressive stress, it has been defined using the Concrete Damaged Plasticity (CDP) model.

[0043] For the clay -based material, plastic strain (Epi), inelastic strain (Ein), and damage parameter (D) were determined using experimentally obtained stress-strain relationships.

[0044] Two different types of vertically perforated bricks, commonly used in the construction of masonry structures, were numerically modeled in the finite element analysis software as Reference-1 (1) and Reference-2 (2), incorporating their physical dimensions, void ratios, and material properties.

[0045] The reference bricks were subjected to displacement-controlled loading in three different axes (X, Y, Z). Loading in the X direction (3) was applied as horizontal displacement-controlled loading along the long side of the brick; loading in the Y direction (4) was applied as horizontal displacement-controlled loading along the short side of the brick; and loading in the Z direction (5) was applied as vertical displacement-controlled loading along the vertical axis of the brick.

[0046] Under these loading conditions, the stress-strain behaviors of both bricks were investigated, and the strength capacity and deformation characteristics in each axiswere determined. The results revealed how both bricks behave in different axes and demonstrated which brick type exhibits better performance in which axis.

[0047] Upon examination, it was observed that the Reference-1 (1) brick exhibited the superior performance in strength tests across three different directions.

[0048] Independently of the characteristics of the reference bricks, 12 different alternative void geometries were modeled and analyzed.

[0049] Each alternative was initially subjected to loading in the Z direction, and the patterns yielding results comparable to the reference samples were selected.

[0050] From among these alternative geometries, the brick geometries No. 10 and No. 11, which exhibited the best performance, were selected for further analyses and comparisons.

[0051] In the analytical studies conducted on the alternative void geometry designs, it was observed that the designs featuring a central arch form in the middle section yielded better results in all directions.

[0052] In order to further investigate this effect, 2 different brick geometries possessing the same arch structure were designed.

[0053] The structural performance of brick designs having different h / w ratios was evaluated through load-displacement analyses performed in all three directions (X, Y, Z). These analyses clearly demonstrate the effects of the arch geometry on loadbearing capacity and deformation resistance.

[0054] In the operations performed, the existing brick design No. 11 was evaluated as having the generally most suitable h / w ratio for all three directions. This ratio provided the most reliable result in terms of both the load-bearing capacity and energy dissipation of the brick.Weaknesses were detected in the X direction depending on the h / w ratios. Therefore, the brick design No. 11, which provided the best results, was further developed to create a new brick design of the subject invention (No. 13).

[0055] In the brick design of the subject invention (No. 13), the weaknesses in the X direction were eliminated, and the highest increase in strength and energy dissipation within the scope of the invention was achieved in this design.

[0056] In the final stage, comparisons were made between the Reference-1 brick (which exhibited the best performance), the No. 10 and No. 11 bricks, and the brick of the subject invention in terms of structural performance parameters.

[0057] Overall, while the brick of the subject invention (No. 13) presented the highest performance in terms of load-bearing capacity, it was observed that the brick designs No. 10 and No. 11 also provided significant improvements in specific directions.

[0058] The Concrete Damaged Plasticity (CDP) model used in modeling the clay-based fired brick material accounts for the material's damage mechanism, plastic behavior, and compressive and tensile behaviors. Compared to other models, it possesses the capability to approximate results with greater accuracy. This model is particularly effective in capturing the complex interactions between tensile and compressive responses, which are critical for simulating the structural performance of masonry materials under various loading conditions. The yield stress, inelastic strain, plastic strain values, and related damage parameters used in defining the CDP model have been carefully calibrated to reflect the specific behavior of this clay-based material, ensuring that the numerical model closely simulates the physical responses observed in experimental tests. The clay-based fired material was defined in the finite element analysis software using CDP model parameters; this is crucial for predicting the onset and progression of damage.The plasticity parameters entered while defining the CDP model are determined as follows: Dilation angle (y) 30°, Flow potential eccentricity (C) 0.1, fto / fco ratio 1.16, Shape factor (K) 1, and Viscosity parameter (p) 0.001. These specific values were selected based on a combination of empirical data and literature values and were optimized to capture both immediate and progressive damage of the model under cyclic loading conditions. In order to verify the accuracy of the CDP model behavior defined in the software, a cube specimen with dimensions of 150*150*150 mm was modeled and analyzed under compressive loading. This verification step is crucial as it provides confidence in the model's capability to accurately simulate the real-world behavior of the material under similar loading conditions. It was observed that the numerical stress-strain curve under compression of the cube specimen modeled with the CDP model technique was very close to the experimentally obtained curve. The close match between numerical and experimental results not only validates the use of the CDP model for this study but also highlights its robustness in simulating the complex behavior of masonry materials. Thus, it was decided that the CDP model could be used in this parametric study. Consequently, the validated CDP model was used to conduct a series of parametric analyses aimed at investigating the effects of different material properties and loading conditions on the structural performance of perforated bricks.

[0059] The reference bricks selected for guidance purposes, designated as Reference- 1 (1) and Reference-2 (2), possess geometrically distinct void structures; consequently, they exhibit different structural behaviors. The total surface area of the Reference-1 brick was determined to be 19,649 mm2. This brick features a large central void located in its center, supported by smaller voids arranged symmetrically around it. This configuration is designed with the aim of optimizing both the load-bearing capacity and the weight of the brick. The total surface area of the Reference-2 brick is 17,336 mm2. Unlike Reference-1, the Reference-2 brick features two large rectangular voids in its center. While this brick presents a structure potentially possessing a wider load-bearing capacity, the material thicknesses between thevoids also support this design. The CDP model was used to accurately reflect the mechanical properties of the bricks. The reference bricks were loaded in three different axes (X, Y, Z) under displacement control. Loading in the X axis was applied as horizontal displacement-controlled loading along the long side of the brick; loading in the Y axis was applied as horizontal displacement-controlled loading along the short side of the brick; and loading in the Z axis was applied as vertical displacement-controlled loading along the vertical axis of the brick. It was considered that the loading applied to the brick units in the X direction represents the behavior under out-of-plane loads, the loading in the Y direction represents the in-plane behavior, and the loading performed in the Z direction represents the behavior under vertical loads. The analyses were performed using implicit solution methods, thereby ensuring the accurate modeling of the specimens under complex loading conditions. During modeling, the mesh size was selected as 5 mm as a standard in all analyses, which optimized both accuracy and computational time. In the model generated for the reference specimen, 34,078 nodes and 18,279 elements were created using C3D8R element types. This numerical modeling was executed on a computer with 64 GB of RAM and 16 cores. Parallel processing capabilities were utilized to optimize the computation time. Under these loading conditions, the stress-strain behaviors of both bricks were investigated, and the strength capacity and deformation characteristics in each axis were determined. The results revealed how both bricks behave in different axes and demonstrated which brick type exhibits better performance in which axis.

[0060] The geometries of 12 independent designs for the hollow clay bricks to be developed were designed with the aim of improving the load-bearing capacity and overall structural performance of the bricks by utilizing the advantages of arch and truss systems. By carefully evaluating the physical properties and void structures of each geometry, models suitable for numerical analyses were created.

[0061] Initially, each alternative was subjected to loading in the Z direction, and the patterns yielding results comparable to the reference specimen were selected. Theanalysis results revealed that specific arch and truss patterns significantly improved the overall durability of the structures by enhancing the rigidity and energy absorption capacity of the bricks. Some of these distinct geometries exhibited better performance than the reference bricks in certain directions. In particular, the No. 10 and No. 11 bricks, which feature arch-shaped central voids, yielded highly favorable results in terms of structural performance parameters. From among these alternative geometries, the two geometry types demonstrating the best performance were selected for further analyses and comparisons. The selected geometries are those possessing the highest values in terms of critical performance parameters such as rigidity, load-bearing capacity, and energy absorption capacity.

[0062] In the analytical studies conducted on the alternative void geometry designs, it was observed that the designs featuring a central arch form in the middle section yielded better results in all directions. As is known, the variation of the height-to-width ratio (h / w) in arch structures significantly alters the structural behavior.

[0063] Based on this finding, the influence of the variation in the height-to-width (h / w) ratio of the arch geometry present within the design on the behavior of the brick was also investigated. In the existing brick design No. 11, the h / w ratio of the central arch was determined as 0.56 (7). Using the results of this design as a reference, two additional different designs having h / w ratios of 0.42 (6) and 0.85 (8), respectively, were developed in order to investigate this effect in greater depth. The structural performance of the brick designs possessing different h / w ratios was evaluated through load-displacement analyses performed in all three directions (X, Y, and Z). These analyses clearly demonstrate the effects of the arch geometry on load-bearing capacity and deformation resistance. The design possessing an h / w ratio of 0.42 (6) presented the highest load-bearing capacity in loadings applied from the short side (Y direction), whereas it exhibited lower performance in the other directions. Although the flatter nature of the arch in this design allowed for the distribution of loads over a wider area in the Y direction, the load-bearing capacity remained limited in loadings applied from the long side (X direction) and in the verticaldirection (Z direction). The h / w ratio of 0.56 (7) exhibited a balanced and high performance in all three directions. While achieving the best load-bearing capacity in loadings applied from the long side (X direction) and in the vertical direction (Z direction), it also demonstrated reasonable performance in loadings applied from the short side (Y direction). This ratio provided the most optimal results by ensuring the best adaptation to loading conditions in all directions. The design possessing an h / w ratio of 0.85 (8), although exhibiting reasonable performance in the X direction, demonstrated lower capacity in the Y and Z directions. The higher nature of the arch caused stress concentration in certain directions and consequently led to a decrease in capacity. When evaluated generally, while the h / w = 0.56 ratio offered the best performance in both X and Z directions, the h / w = 0.42 ratio demonstrated a higher capacity in the Y direction. However, the h / w = 0.56 (7) ratio stands out as the design providing the most balanced and optimal performance in all directions. This ratio optimizes the load-bearing capacity of the arch geometry while simultaneously increasing the strength in different directions. Therefore, the generally most suitable h / w ratio for all three directions can be evaluated as 0.56, i.e., the existing brick design No. 11. This ratio provided the most reliable result in terms of both the load-bearing capacity and energy dissipation of the brick. It was determined that the brick design having an h / w ratio of 0.42 provided a significant structural performance increase in the Y direction (in-plane loading) compared to other designs, but failed in the X direction. Thereupon, in order to utilize the advantage of the increase in the Y direction in this design and to improve the behavior in the X direction, points constituting weaknesses in terms of load transfer were identified. By eliminating the identified weaknesses, a new brick design named No. 13, having an h / w ratio of 0.42, was developed. Technical drawings of the No. 11 brick and the No. 13 brick are presented in Figure 6.

[0064] When the load-displacement relationships shown in Figure 5 are analyzed, the following technical conclusions are derived.1. Increased Load-Bearing Capacity: The new brick designs provide higher loadbearing capacity of up to 25% in the X direction, up to 39% in the Y direction, and up to 9% in the Z direction, thereby increasing the resistance of the structure under dynamic loads such as earthquakes. The X direction represents out-of-plane forces, the Y direction represents in-plane forces, and the Z direction represents vertical loading. These increases indicate a significant improvement, particularly in the Y direction.

[0065] 2. Higher Rigidity: These designs provide higher rigidity of up to 13% in the Y direction and up to 12% in the Z direction. This rigidity performance across directions ensures a more stable structure by minimizing structural deformations, particularly due to the high rigidity provided in the Y and Z directions. As for the X direction, this decrease in rigidity is compensated by the advantages in the other directions.

[0066] 3. High Energy Dissipation Capacity: The new brick designs dissipate energy more effectively under dynamic loads such as earthquakes. They possess a higher energy dissipation capacity of up to 300% in the X direction, up to 283% in the Y direction, and up to 21% in the Z direction. These increases offer an exceptional improvement, particularly in the Y direction, thereby significantly enhancing the performance of structures under dynamic loads.

Claims

CLAIMS1. A hollow clay-based fired masonry building brick relating to improving structural performance by developing alternative void geometries in order to increase resistance against earthquakes and other external loads in masonry structures, characterized in that it comprises;a rectangular body (9),- beam and / or truss system elements (10) having different dimensions in horizontal and vertical directions, formed within the body, arched structures (11) formed by providing a connection on the beams close to the side surface of the body.

2. The hollow masonry building brick according to Claim 1, characterized in that the height-to-width ratio defined for the arch form located in the inner part is 0.42.

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