# Effect of Wood Densification and GFRP Reinforcement on the Embedment Strength of Poplar CLT
###### Abstract
However, a thorough examination is necessary to develop novel approaches that include relevant derived factors for the designer's benefit [10]. Numerous factors influence the embedment strength of wood and engineered wood products (EWPs), including the type of wood species, density, moisture content, loading direction, dowel diameter, and so on [12]. Multiple studies have evaluated the embedment strength of connectors in CLT. [PERSON] and [PERSON] [13] and [PERSON] and [PERSON] [14; 15; 16] conducted the first investigations of the embedment strength of laterally loaded dowel-type fasteners in CLT. [PERSON] et al. [17] observed that wood density and embedment strength are related. This positive correlation was also reported by [16]. A study on the nail-bearing strength of hybrid CLT composed of Japanese larch and yellow poplar [18] revealed that increasing the higher ratio of minor lamina thickness to nail depth resulted in a lower embedment strength in the hybrid CLT. To obtain effective bearing resistance of the nail connection, the length of the nail used for the mixed CLT should be chosen based on the thickness of the minor lamina. Several additional studies [19; 20; 21; 22] have investigated the embedment strength of connectors in CLT and wood-based products. They worked on the embedment strength of EWPs such as CLT made of various wood species. The timber species used to manufacture CLT significantly affects its properties. poplar is a fast-growing tree, which is advantageous in nations with a wood supply shortage. Several studies have examined the CLT properties of fast-growing timber species [23; 24; 25; 26; 27; 28; 29]. It is essential to reinforce the wood, notably at vulnerable connection points [30]. In addition, the low density of certain wood species, such as poplar, may results in undesirable mechanical properties. There are various techniques to reinforce EWPs and improve the mechanical strength of timber structures, including but not limited to reinforcement using metals or fiber-reinforced polymers (FRPs). According to [PERSON] and [PERSON] [31], reinforcing the connections aims to preserve the continuity of structures and lessen the drawbacks of connection elements with nails and bolts. Several investigations on concrete [32; 33], metal plates [32; 34; 35; 36], rods, and bars as reinforcement in wood-based products have been performed. Additionally, FRPs can be used in different ways for reinforcement [37]. Due to their strength-to-weight ratio, glass-fiber-reinforced polymers (GFRPs) appear to be an optimal fiber type for reinforcing wood components [31]. Douglas fir split timber stringers were strengthened for shear and bending forces with GFRP layers. Depending on the severity of beam fracture prior to reinforcement, the proposed strengthening design increased the stiffness [38]. [PERSON] et al. [39] showed that diagonal (0-90\({}^{\circ}\) lay-up) GFRP layers were more effective than vertical ones in shear-strengthening creosote-treated Douglas fir beams with horizontal fractures at their extremities. The mechanical characteristics of connecting points of fiber-reinforced longitudinal notched lap joints fabricated from black pine lumber were investigated [31]. The results demonstrated that GFRP could be utilized as a connecting mechanism for timber members. [PERSON] et al. [40] created a GFRP wood-affixed connection as a replacement due to the potentially corrosive character of steel-plated pine wood connectors. According to their findings, the majority of GFRP wood-bolted connectors failed due to the bearing failure of the bolt openings in the wood panels when subjected to lateral tension load. Densification is another method for enhancing the mechanical properties of timber and timber-based products that increases the strength, hardness, and abrasion resistance of timber [41]. Densified timber can be utilized by creating laminates and processing the densified wood with a similar construction to that of laminated veneer lumber (LVL), gluelaminated timber (Glulam), and CLT.