These defects can occur in the form of cracks, pain deterioration, dampness, etc. due to mechanical and weathering effects. Crack identification and categorization must be part of the inspection procedure for civil engineering structures. Convolutional neural networks (CNNs), a sub-type of deep learning (DL), can automatically classify the defective images of wooden structures. In this research, 10 pre-trained models of CNN, including ResNet18, ResNet50, ResNet101, Inception-V3, GoogleNet, ShuffleNet, InceptionResNet-V2, MobileNet-V2, XceptionNet, and NASNet-Mobile are evaluated for classification and prediction of defects in wooden structures. After prediction of class, the algorithm calculated the angle, length, and width of cracks with quantification errors of 0.15%, 1.54%, and 4.2% for first testing image, and 2.3%, 0.99%, and 2% for second testing image.
Top1. Background Study
Wooden structures are common in construction, particularly in residential and light commercial buildings. They can be used for a wide range of purposes, including load-bearing walls, framing for floors and roofs, and as support for cladding materials such as brick or siding. There are several different types of wooden structures used in construction, including:
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Timber framing: This is a traditional method of construction that involves using large, solid wood beams and joints to create the structural frame of a building.
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Glued laminated timber (glulam): This is a type of structural timber that is made by gluing together layers of dimensional lumber. It is often used in long spans, such as in gymnasiums or bridges.
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Laminated veneer lumber (LVL): This is a type of engineered wood that is made by bonding together layers of veneer. It is used in applications where high strength and stiffness are required, such as in beams and headers.
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Engineered wood products: These are products that are made from wood fibers and adhesives, and are designed to provide specific structural properties. Examples include oriented strand board (OSB) and plywood.
Overall, wooden structures are valued for their strength, durability, and aesthetic appeal. They are also a renewable resource and can be sustainably managed. However, wood is vulnerable to moisture damage and must be properly protected and maintained to ensure its longevity. Cracks and knots in wooden structures can be caused by a variety of factors, including changes in humidity and temperature, mechanical stress, and insect infestation. Cracks may occur naturally in the wood as it ages, or they may be the result of improper installation or maintenance. Knots are formed when branches or limbs grow from the trunk of a tree and are later cut off, leaving a knot in the wood. These knots can weaken the structural integrity of the wood and may cause cracks to form. To prevent cracks and knots from affecting the structural integrity of a wooden structure, it is important to properly design and construct the structure, maintain it regularly, and use wood that has been properly seasoned and treated to prevent insect infestation.
Top2. Defects In Wooden Structures
Cracks and knots in wooden structures can be caused by a variety of factors, including changes in humidity and temperature, mechanical stress, and insect infestation. Cracks may occur naturally in the wood as it ages, or they may be the result of improper installation or maintenance. Knots are formed when branches or limbs grow from the trunk of a tree and are later cut off, leaving a knot in the wood. These knots can weaken the structural integrity of the wood and may cause cracks to form. To prevent cracks and knots from affecting the structural integrity of a wooden structure, it is important to properly design and construct the structure, maintain it regularly, and use wood that has been properly seasoned and treated to prevent insect infestation.
There are several types of defects that can occur in wooden structures, including:
Cracks: Cracks in wooden structures are occurred due to the overloading, shrinkage, or expansion effect as illustrated in Figure 1. The cracks decrease the strength of wood and if that part is a structural member then it cannot be ignored.
Knots: Knots in wooden structures can be a source of strength or weakness, depending on the type of knot and the direction of the load applied to the structure. If a knot is located in a critical structural member and cannot be avoided, it may be necessary to use a larger size of wood or to reinforce the member in some other way to compensate for the reduced strength of the knot.
Warp: Warp is a term used to describe any deviation from a flat or straight condition in a piece of wood. There are several types of warp, including bow, crook, cup, and twist. Warp can be caused by improper drying of the wood, changes in humidity, or mechanical stress.
Splits: Splits occur when the wood fibers separate along the grain. They can be caused by mechanical stress, changes in humidity, or defects in the wood itself.
Checks: Checks are shallow, narrow splits that occur on the surface of the wood. They are usually caused by changes in humidity or the presence of knots.