• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.721-724
• /
• 2008

The present study was to develop a dry PFB method similar to the existing gypsum board construction method in order to apply the existing wet PFB method that uses fire.resistant adhesive. It was found that the existing wet method can produce concrete compressive strength of 80MPa and fire resistance of 3 hours with 30mm PF boards. The goal of development in this study was fire resistance of 3 hours through dry construction of 15mm fire resistant boards. The results of fire resistance test showed an increase in thermal durability and thermal strain. It is believed that inorganic fiber reduces thermal strain, and lowers heat insulation performance by 15% or less. This suggests that heat insulation performance was improved by the change in the inner composition of PF board resulting from the adjustment of Al:Si mol ratio, high temperature molding, and dry curing. According to the results of fire resistance test, when the dry PF method was applied, the temperature of the main reinforcing bar was 116$^\circ$C in 15mm, 103.8$^\circ$C in 20mm, and 94$^\circ$C in 25mm, and these results satisfied the current standards for fire resistance control presented by the Ministry of Land, Transport and Maritime Affairs. When a 3 hour fire resistance test was performed and the external properties of the specimen were examined, the outermost gypsum board hardly remained and internal PF board maintained its form without thermal strain.

• Journal of the Korea Concrete Institute
• /
• v.26 no.4
• /
• pp.491-497
• /
• 2014

The corrosion of steel reinforcement in reinforced concrete bridge decks significantly affects the degradation of the capacity. Due to the advantageous characteristics such as high tensile strength and non-corrosive property, fiber reinforced polymer (FRP) has been gathering much interest from designers and engineers for possible usage as a alternative reinforcement for a steel reinforcing bar. However, its application has not been widespread, because there data for short- and long-term performance data of FRP reinforced concrete members are insufficient. In this paper, seven full-scale decks with dimensions of $4000{\times}3000{\times}240mm$ were prepared and tested to failure in the laboratory. The test parameter was the bottom reinforcement ratio in transverse direction. The decks were subjected to various levels of concentrated cyclic load with a contact area of $577{\times}231mm$ to simulate the vehicle loading of DB-24 truck wheel loads acting on the center span of the deck. It was observed that the glass FRP (GFRP) reinforced deck on a restraint girder is strongly effected to the level of the applied load rather than the bottom reinforcement ratio. The study results showed that the maximum load less than 58% of the maximum static load can be applied to the deck to resist a fatigue load of 2 million cycles. The fatigue life of the GFRP decks from this study showed the lower and higher fatigue performance than that of ordinary steel and CFRP rebar reinforced concrete deck. respectively.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.1
• /
• pp.73-80
• /
• 2022

In this study, details of NRC beam-column connections were developed in which beam and columns pre-assembled in factories using steel angles were bolted on site. The developed joint details are NRC-J type and NRC-JD type. NRC-J type is a method of tensile joining with TS bolts to the side and lower surfaces of the side plate of the NRC column and the end plate of the NRC beam. NRC-JD type has a rigid joint with high-strength bolts between the NRC beam and the side of the NRC column for shear, and with lap splices of reinforcing bar penetrating the joint and the beam main reinforcement for bending. For the seismic performance evaluation of the joint, three specimens were tested: an NRC-J specimen and NRC-JD specimen with NRC beam-column joint details, and an RC-J specimen with RC beam-column joint detail. As a result of the repeated lateral load test, the final failure mode of all specimens was the bending fracture of the beam at the beam-column interface. Compared to the RC-J specimen, the maximum strength of the specimen by the positive force was 10.1% and 29.6% higher in the NRC-J specimen and the NRC-JD specimen, respectively. Both NRC joint details were evaluated to secure ductility of 0.03 rad or more, the minimum total inter-story displacement angle required for the composite intermediate moment frame according to the KDS standard (KDS 41 31 00). At the slope by relative storey displacemet of 5.7%, the NRC-J specimen and the NRC-JD specimen had about 34.8% and 61.1% greater cumulative energy dissipation capacity than the RC specimen. The experimental strength of the NRC beam-column connection was evaluated to be 30% to 53% greater than the theoretical strength according to the KDS standard formula, and the standard formula evaluated the joint performance as a safety side.