• Structural Engineering and Mechanics
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• 제49권6호
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• pp.673-685
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• 2014

The topic of this study is to strengthen cracked beams with prefabricated RC U cross-sectional plates. The damaged beams were repaired by epoxy based glue. The repaired beams were strengthened using prefabricated plates. The strengthening plates were bonded to the bottom and side faces of the beams by anchorage rods and epoxy. The strengthened beams were incrementally loaded up to maximum load capacities. The experimental results were satisfactory since the load carrying capacities of damaged beams were increased approximately 76% due to strengthening. It was observed that strengthening plates had a dominant effect on the performance of beams in terms of both the post-elastic strength enhancement and the ductility. The experimental program was supported by a three-dimensional nonlinear finite element analysis. The experimental results were compared with the results obtained from the beam modeled with ANSYS finite element program.

• Structural Engineering and Mechanics
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• 제81권3호
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• pp.305-316
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• 2022

Externally bonded ultrahigh performance fiber-reinforced concrete (UHPFRC) is commonly used as a strengthening material for reinforced concrete (RC) structures. This study reports the results of an experimental program investigating the bonding behavior between concrete and prefabricated UHPFRC plates. The overall experimental program is consisting of five RC specimens, which are strengthened using the different lengths and widths of prefabricated UHPFRC plates. These specimens were analyzed using the pull-pull double-shear test. The performance of each strengthened specimen is presented, discussed and compared in terms of failure mode, maximum load, load-slip relationship, fracture energy and strain distribution. Specimen C-25-160-300 which bonded along the whole width of 160 mm recorded the highest maximum load (109.2 kN) among all the analysed specimens. Moreover, a 3D numerical finite element model (FEM) is proposed to simulate the bond behavior between concrete and UHPFRC plates. Moreover, this study reviews the analytical models that can predict the relationship between the maximum bond stress and slip for strengthened concrete elements. The proposed FEM is verified against the experimental program and then used to test 36 RC specimens strengthened with prefabricated UHPFRC plates with different concrete grades and UHPFRC plate widths. The obtained results together with the review of analytical models helped in the formation of a design equation for estimating the bond stress between concrete and prefabricated UHPFRC plates.

• Smart Structures and Systems
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• 제24권6호
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• pp.783-791
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• 2019

Prefabricated reinforced-concrete shear walls are used extensively in building structures because they are convenient to construct and environmentally sustainable. To make large walls easier to transport, they are divided into smaller segments and then assembled at the construction site using a variety of connection methods. The present paper proposes a precast shear wall assembled using steel shear keys, wherein the shear keys are fixed on the embedded steel plates of adjacent wall segments by combined plug and fillet welding. The anchoring strength of shear keys is known to affect the mechanical properties of the wall segments. Loading tests were therefore performed to observe the behavior of precast shear wall specimens with different anchoring components for shear keys. The specimen with insufficient strength of anchoring components was found to have reduced stiffness and lateral resistance. Conversely, an extremely high anchoring strength led to a short-column effect at the base of the wall segments and low deformation ability. Finally, for practical engineering purposes, a design approach involving the safety coefficient of anchoring components for steel shear keys is suggested.

• 국제강구조저널
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• 제18권5호
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• pp.1639-1653
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• 2018

Bolted connections are suitable due to high quality prefabrication in the factory and erection in the workplace. Prefabrication and modularization cause high speed of erection and fabrication, high quality and quick return of investment. Their technical hitches transportation can be removed by prefabrication of joints and small fabrication of components. Box-columns are suitable members for bolted structures such as welded steel structures with moment frames in two directions etc., but their continual fabrication in multi-story buildings and performing the internal continuity plate in them will cause some practical dilemmas. The details of the proposal technique introduced here, is to remove such problems from the box columns. Besides, some other advantages include new prefabricated bolted beam-to-column connections referred to BBCC. This connection is a set of plates joined to columns, beams, support, and bolts. For a better understanding of its fabrication and erection techniques, two connection and one structural maquettes are made. The present work aims to study the cyclic behavior of connection numerically. To verify the accuracy of model, a similar tested connection was modelled. Its verification was then made through comparison with test results. The behavior of connection was evaluated for an exterior connection using three different support shapes. The effects of support shapes on rigidity, ductility, rotation capacity, maximum strength, four rad rotation strength were compared to those of the AISC seismic provision requirements. It was found that single beams support has all the AISC seismic provision requirements for special moment frames with and without a continuity plate, and box with continuity plate is the best support in the BBCC connection.

• 한국구조물진단유지관리공학회 논문집
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• 제20권3호
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• pp.1-9
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• 2016

데크플레이트 철판을 성형하여 구성한 DH-Beam은 형틀 역할 뿐 아니라 합성거동에 기여할 것으로 판단되며, 본 연구에서는 DH 측판의 전단강도 기여도를 평가하고자 하였다. 총 5개의 실험체를 대상으로 실험 및 해석적 연구를 수행하였다. 실험체는 2개의 정가력 실험체, 2개의 부가력 실험체, 그리고 1개의 RC 실험체로 구성되었다. RC 실험체는 DH-Beam과 비교를 목적으로 제작하였다. DH-Beam에 대한 실험결과는 전단강도를 산정하는 설계식 그리고 RC 실험체에 대한 실험결과 등과 비교하였으며, 그 결과 DH-Beam의 측판은 전단강도에 기여하고 있다. 비선형 구조해석에서는 실험체를 대상으로 DH 판의 기여도를 평가하였다. 구조해석에서는 DH 측판 만 있는 경우 혹은 DH 판이 전혀 없는 경우 등 다양한 경우를 대상으로 하였다. 구조실험 및 해석적 연구의 결과 DH-Beam의 측판은 콘크리트와 합성단면을 형성하면서 전단강도에 기여하는 것으로 평가할 수 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1202-1205
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• 2009

Embankment preloading, in conjunction with prefabricated vertical (PV) drains, was used to accelerate consolidation of marine clays in Pusan New Harbour project. UP to eightteen settlement plates were installed at the ground reclamated site under the embankment fill to monitor the preload performance. This analysis is carried out by five settlement prediction methods including the Asaoka, Hyperbolic, Hoshino, and back-analysis method based on optimization. The field settlement data can be analysed by settlement prediction methods to predict the ultimate settlement and the degree of consolidation of the reclaimed land under charge fill. The authors compared with the analyzed results of the methods.

• 콘크리트학회논문집
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• 제26권2호
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• pp.171-179
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• 2014

이 연구는 DH beam의 구조성능을 평가하는 것을 목적으로 하였다. DH beam을 사용하는 DH 공법은 얇은 철판을 성형하여 거푸집 및 구조적 역할을 할 수 있는 철판을 철근과 함께 공장에서 선조립하여 현장으로 반입하여 콘크리트를 타설하는 공법이다. 이 때 DH 판이 거푸집 역할 뿐 아니라 휨강도에 기여할 것으로 여겨져서 이 연구에서는 DH 판의 휨강도 기여도를 평가하고자 하였다. 총 5개의 실험체를 대상으로 실험 및 해석적 연구를 수행하였다. 실험체는 2개의 정모멘트 실험체, 2개의 부모멘트 실험체, 그리고 1개의 RC 실험체로 구성되었다. RC 실험체는 DH beam과 비교를 목적으로 제작하였다. DH beam에 대한 실험 결과는 휨강도를 산정하는 설계식 그리고 RC 실험체에 대한 실험 결과 등과 비교를 통하여 DH beam은 철판이 항복하면서 충분히 휨강도에 기여하고 있음을 알 수 있었다. 그리고 비선형 구조해석에서는 두 개의 실험체에 대하여 DH 판이 있는 경우와 없는 경우를 대상으로 휨강도, 콘크리트의 주인장변형률, 그리고 철근의 응력을 비교하였으며, 해석에서도 DH 판이 휨강도에 충분히 기여함을 알 수 있었다. 이상과 같은 실험 및 해석적 연구의 결과 DH beam의 철판은 콘크리트와 합성단면을 형성하여 충분한 휨강도를 갖는 것으로 보였다.

• 한국강구조학회 논문집
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• 제29권3호
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• pp.249-260
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• 2017

볼트접합 앵글을 사용한 선조립-SRC 합성기둥(이하 PSRC 합성기둥)의 구조성능을 평가하기 위하여 PSRC 기둥실험체 6개와 일반 SRC 기둥실험체 2개에 대하여 편심축 압축실험을 수행하였다. 횡보강재의 수직간격 및 단면형상과 축하중의 편심율을 실험변수로 고려하였다. 실험결과, 편심율이 큰 경우 PSRC 실험체는 단면 코너에 위치한 고강성 앵글로 인하여 압축하중 재하능력 및 변형능력이 기존 SRC 실험체보다 향상되었다. PSRC 기둥 실험체에서 횡방향 강판의 좁은 횡보강 간격과 Z형 단면의 횡방향 강판은 우수한 횡구속력을 제공하였으며, 하중재 하능력을 향상시켰다. 실험 및 수치해석을 통한 합성기둥의 휨 압축 강도는 현행설계기준에 의한 휨-압축 상관도를 상회하였다. 수치해석결과는 각 실험체의 강성, 최대강도, 최대하중 이후 강도감소거동을 비교적 잘 예측하였다.

• 한국강구조학회 논문집
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• 제29권2호
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• pp.147-158
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• 2017

본 연구에서는 볼트조립 앵글을 적용한 선조립 합성기둥(이하 PSRC 합성기둥)의 압축성능을 연구하였다. 2/3 축소비율의 PSRC 기둥실험체 4개와 기존 SRC 기둥실험체 2개에 대하여 중심축 압축실험을 수행하였다. 횡보강재의 수직간격 및 단면형상과 앵글의 단면형상을 실험변수로 고려하였다. 실험결과, PSRC 기둥실험체는 기존 SRC 기둥실험체와 비교하여 비슷한 압축하중 재하능력 및 변형능력을 발휘하였다. PSRC 합성기둥의 경우, 횡방향 강판의 좁은 횡보강 간격과 Z형 단면의 강판이 압축강도 및 변형능력 향상에 효과적인 것으로 나타났다. 또한 PSRC 합성기둥은 현행설계기준에 의한 공칭 압축강도보다 큰 압축하중 재하능력을 나타내었다. 실험체들에 대한 수치해석결과는 피복 콘크리트 탈락으로 인한 하중감소를 제외하고 초기강성 및 하중재하능력을 비교적 잘 예측하였다.

• Steel and Composite Structures
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• 제26권4호
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• pp.463-471
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• 2018

The bolted end-plate beam-column connections have been widely used in steel structure and composite structure because of its excellent seismic performance. In this paper, the end-plate bolted connection is applied in the concrete structure, A new-type of fabricated beam-column connections with end-plates is presented, and steel plate hoop is used to replace stirrups in the node core area. To study the seismic behavior of the joint, seven specimens are tested by pseudo-static test. The experimental results show that the new type of assembly node has good ductility and energy dissipation capacity. Besides, under the restraint effect of the high-strength stirrup, the width of the web crack is effectively controlled. In addition, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.