본 연구에서는 구조용 집성재 접합부에 접합철물을 대신하여 목재와 유리섬유보강재를 복합시킨 GFRP 보강적층판과 삽입접착형 GFRP rod를 접합물로 사용하였다. 또한 이들을 적용시킨 라멘 접합부에 대한 모멘트 저항 성능 및 실대재 문형라멘 골조의 수평가력 성능 시험을 통해 접합내력 성능을 평가하였다.
라멘 접합부에 적용하기 위해 FRP 보강적층판을 제작하였으며, KS F 3021과 KS F 2160에 의거한 침지박리 시험과 내수 침지박리 시험 및 ASTM D5045-99에서 제안한 Compact Tension(CT)형 파괴인성 시험을 진행한 결과. Type-4 GFRP Textile-Sheet 보강적층판이 접착성능과 파괴인성성능이 가장 양호한 것으로 확인되었다.
또한 라멘 접합부의 경량화 및 연성을 높이기 위한 GFRP rod 삽입 접합부의 접착성능 시험 결과. 에폭시 접착제 사용 시 GFRP rod와 집성재간의 접착강도는 폴리우레탄 접착제 사용 시 보다 평균 40% 높게 측정되었으며, 세부 조건으로는 GFRP rod의 표면이 거칠며 삽입깊이가 6D(D:Rod의 직경), 접착 층의 두께가 3mm일 때 가장 효율적인 성능을 발휘하는 것으로 확인되었다.
두 종류의 접합방법을 낙엽송 집성재 라멘구조의 접합부에 적용하였으며, 라멘 접합부에 대한 모멘트 저항 시험 및 라멘 구조의 반복 수평가력을 가하여 내력성능을 평가하였다. 모멘트 저항 시험결과, 철물접합부인 TypeⅠ과 비교하여 GFRP 보강적층판과 GFRP rod 핀을 사용한 TypeⅡ의 항복모멘트는 4% 낮게 측정되었으나 회전강성은 29% 높게 측정되었다. 또한 GFRP 보강적층판과 목재 핀을 사용한 TypeⅢ은 TypeⅠ과 비교하여 항복모멘트는 11%, 회전강성은 56%높게 측정되어 가장 높은 성능을 발휘하였다. 반면, GFRP rod를 접합물로 사용한 TypeⅣ와 TypeⅤ는 접착 불량으로 측정이 불가하거나 접합성능이 매우 낮게 측정되었다.
라멘 구조에 대한 반복 수평가력 시험결과는 모멘트 저항 시험에 대한 결과와 그 경향이 비슷하였다. GFRP 보강적층판과 GFRP rod 핀을 사용한 RahmenⅡ는 철물접합부인 RahmenⅠ과 비교하여 항복내력의 차이를 8%까지 줄이는데 성공하였다. GFRP 보강적층판과 목재 핀을 사용한 RahmenⅢ은 RahmenⅠ과의 항복내력 차이가 2%에 불과해 거의 비슷한 성능을 발휘한 것으로 확인되었다. 반면, 모멘트 저항 시험에서 가장 낮은 성능을 발휘한 GFRP rod 접합부는 라멘구조의 수평가력 시험에서도 마찬가지로 가장 낮은 항복내력이 측정되었다.
이러한 시험 결과를 종합하여 보았을 때, GFRP rod를 이용한 접합부는 GFRP rod와 집성재 간의 접착력이 중요한 내력 기구로 현장적용 시 문제가 발생할 수 있는 가능성이 크다고 판단된다. 정확한 접착을 위한 목재의 품질관리와 정밀한 접착공정이 요구된다. 또한 실용화를 위해서는 접착공정 뿐 아니라 이에 대한 추가적인 보강 방법 고안이 필요할 것으로 생각된다. 반면, GFRP 보강적층판을 이용한 낙엽송 집성재의 기둥-보 접합부는 강판보다 약 3배 정도 두껍기 때문에 슬릿형 접합부의 경우 부재의 손실을 단점으로 예상했으나 단면적 손실이 큼에도 불구하고 슬릿부에 GFRP 보강적층판의 접착과 압체가 이루어짐으로써 금속철물을 이용한 접합부와 대등한 성능을 발휘하였다. 이는 부재의 일체화가 이뤄졌음을 보여 주며, 특히 GFRP rod핀 보다 목재 핀을 사용함으로써 압입에 의한 접합부의 할렬 취성파괴를 억제할 수 있었던 것으로 분석된다. 추후 GFRP 보강적층판을 사용한 집성재 부재의 외측보강 및 정밀한 접착공정을 통한 부재의 일체화가 이루어질 수 있다면 접합성능이 더욱 증가될 것으로 생각된다.

In this study, with a view to increasing stability, credibility and the degree of joint strength on the joints consisting structural laminated timber, the laminated plates with the composites of timber and fiber reinforcement and the insertion-adhesive type of GFRP rods were used as joint materials instead of the commonly used metal joint materials. Moreover, the performances of joint strength were assessed through a lateral load test for gate type glulam rahmen structure and the moment resistance performances of column-beam joints with those applied.
For resisting the propagation of splitting crack on the joints of a rahmen, the FRP-reinfroced laminated plate has been manufactured; as a result of conducting soaking delamination tests and water proof soaking delamination tests in accordance with KS F3021 and KS F 2160 as well as Compact Tension (CT)-type fracture toughness tests as suggested by ASTM D5045-99, it has been found that the laminated plate with Type-4 GFRP Textile-Sheet is excellent in the adhesion performance and fracture toughness.
In addition, as a result of adhesion performance tests on the insertion joints of GFRP rods for increasing the degree of weight lightening and ductility on the joints of a rahmen structure, the adhesion strength between glued laminated timber and GFRP rods when an epoxy glue was used has been found to be higher by 40% on average than that when poly-urethane glue was used; in terms of detailed conditions, it showed the most effective performances when the surfaces of GFRP rods are coarse and embedment depth is 6D (D: the diameter of Rod) and the bonded thickeness is 3mm.
The two kinds of joint methods were used to the joints of rahmen structures of structural size lumber of larch, the performances of strength were evaluated by applying the repeated lateral load onto the rahmen structures and with the moment resistance tests for rahmen joints. As a result of moment resistance tests, the yield moment of Type Ⅱ, which used GFRP laminated plate and GFRP rod pins, has been measured to be lower by 4% than that of Type Ⅰ, which is a metal joint. However, the rotational stiffness of Type Ⅱ has been found to be higher by 29%. Also, Type Ⅲ for which GFRP laminated plate and wood pins were used has been found to have its rotational stiffness and yield moment higher by 56% and 11% respectively as compared to Type Ⅰ. It showed the highest degree of performance. On the other hand, Type Ⅳ and Type Ⅴ using GFRP rods as their joint materials were found to be hardly measurable or showed a very low degree of joint performance due to the poor condition of adhesion.
The results of the repeated lateral load tests for rigid-framed structures showed a similar tendency to those with moment resistance tests. RahmenⅡ using GFRP lamintaed plate and GFRP rod pins were successful in decreasing the difference of yield strength by 8% as compared to RahmenⅠ, which is a metal joint. The difference of yield strengths between RahmenⅢ using GFRP laminated plate and wood pins as well as with compression pressure applied for joining the joints and RahmenⅠ is only 2%, so it has been found that they have almost a similar performance. On the other hand, GFRP rod joints showing the lowest performances in moment resistance tests were measured to have the lowest yield strength in the same way as in the lateral load tests for rahmen structures.
With all the experiment results summed up, it is considered that there is much possibility that the joints using GFRP rods may generate problems in their application to the site since the GFRP rods, as strength mechanism, have adhesive strength between GFRP rods and glued laminated timber is an important. Quality assurance of timber for exact adhesion and a precise process of adhesion are required. Also, for commercialization, it is considered that not only an adhesion process but the supplemental methods for compensation should be invented. On the other hand, since the beam-column joints of larch glulam joint using GFRP laminted plate is about three times thicker than the steel plates, for its shortcoming, it was expected that there might be a loss of member of framework in the case of slit type joints. However, although there was a great loss of cross-sectional area, it showed a similar performance to the joints using metal materials due to the adhesion and compression of GFRP laminated plate on slits. This proves that members of framework are integrated into one. Especially, the analysis indicates that by using wood pins instead of GFRP rod pins, the fracture is controlled by the wood pins, so that the ductility of joints may be increased. If the exterior of members of framework for glued laminated timber can be strengthened in the future by the use of GFRP laminated plate and the members of framework can be integrated into one by a precise adhesion process, the joint performances are to be further increased.