Mechanical behavior of CFRP on steel surface molded and bonded by vacuum-assisted resin transfer molding technology

Abstract

This research is aimed to develop repair and reinforcement methods with excellent workability and usefulness for steel structural members that have been damaged through aging. Fiber-reinforced plastic, which has been used in various fields in recent years, is also used for building and civil engineering. Especially, it is assumed that carbon fiber-reinforced plastic (CFRP) has light weight and high-strength mechanical properties. Conventional methods of repair and reinforcement using CFRP are mainly hand-lay-up molding methods using carbon fiber sheet and adhesion methods using CFRP plate. However, both methods have some issues. Therefore, we apply the vacuum-assisted resin transfer molding to repair and reinforce steel structural members; the proposal of a construction procedure and a basic investigation of bond strength were carried out. In the basic investigation, a double-strap tensile shear test and a three-point bending test of steel/CFRP composite specimens were carried out. In the double-strap tensile shear test, in order to improve the adhesiveness of CFRP, the adhesive strength against shear force was compared between the specimen pre-coated with resin and a specimen not coated with resin after surface treatment. The results showed that the pre-coated specimen had high strength and stability. In the three-point bending test, bond strength and fracture mode against bending force were analyzed using adhesion length and number of laminated carbon fiber sheets as parameters. From the finite element method, the stress when peeling occurs due to the bending deformation was estimated and compared with the experimental result.

Pilot Demonstration of a Strengthening Method for Steel-Bolted Connections Using Pre-Formable Carbon Fiber Cloth with VaRTM

“…On the other hand, the brace members have sufficient length to allow for bonding, while it is known that the bonding capacity will peak with increasing the bonding length [18]. Thus, we decided the bonding length should be 300 mm for the brace side with a 150 mm uniform carbon fiber layer length and a 150 mm taper length based on the previous fundamental bonding test results [21]. Eventually, the total number of carbon fiber layers needed to minimize step step n was determined as 33 layers (9 layers to adjust the brace thickness, and 24 layers to adjust the height of the bolt head).…”

Experimental Investigations of the Strengthening Effects of CFRP for Thin-Walled Storage Tanks under Dynamic Loads

“…The epoxy resin, namely E810LS (product of Konishi, Osaka, Japan), was adopted to form the CFRP laminates that covered the TSTs. The carbon fiber sheets were bonded with the shells of TSTs using E810LS epoxy via the vacuum-assisted resin transfer molding (VaRTM) method [34]. The elastic modulus and Poisson's ratio of E810LS epoxy are 3 (GPa) and 0.37, respectively, according to the manufacturer's measurements.…”

“…The CFRP layers were connected with TST shells using the vacuum-assisted resin transfer molding (VaRTM) method. The VaRTM method has many advanced characteristics, such as being cost-effective, easy to mold for many kinds of shapes, and having no complicated steel surface preparations needed [34,[40][41][42]. In addition, one of the most outstanding advantages of the VaRTM method is that this method can create a thin lamination with a high fiber content.…”

The relationship between resistances measured by two-probe, Wenner probe and C1760-12 ASTM methods in electrically conductive concretes

“…CF also has superior mechanical properties (Table 2). Recently, CF has been involved in all areas of the construction industry [25][26][27]. Two different lengths (6 mm and 12 mm) of CF were used in equal ratio.…”