• Smart Structures and Systems
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• 제32권2호
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• pp.111-121
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• 2023

This study proposes an automated assembly performance evaluation method for prefabricated steel structures (PSSs) using machine learning methods. Assembly component images were segmented using a modified version of the receptive field pyramid. By factorizing channel modulation and the receptive field exploration layers of the convolution pyramid, highly accurate segmentation results were obtained. After completing segmentation, the positions of the bolt holes were calculated using various image processing techniques, such as fuzzy-based edge detection, Hough's line detection, and image perspective transformation. By calculating the distance ratio between bolt holes, the assembly performance of the PSS was estimated using the k-nearest neighbors (kNN) algorithm. The effectiveness of the proposed framework was validated using a 3D PSS printing model and a field test. The results indicated that this approach could recognize assembly components with an intersection over union (IoU) of 95% and evaluate assembly performance with an error of less than 5%.

• Steel and Composite Structures
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• 제22권3호
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• pp.613-625
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• 2016

The joints of the new prefabricated concrete assemble beam-column joints are put together by the hybrid joints of inserting steel under post-tensioned and non-prestressed force and both beams and columns adopt prefabricated components. The low cyclic loading test has been performed on seven test specimens of beam-column joints. Based on the experimental result, the rotation capacity of the joints is studied and the $M-{\theta}$ relation curve is obtained. According to Eurocode 3: Design of steel structures and based on the initial rotational stiffness, the joints are divided into three types; by equivalent bending-resistant stiffness to the precast beam, the equivalent modulus of elasticity $E_e$ is elicited with the superposition method; the beam length is figured out that satisfies the rigid joints and after meeting the requirements of application and safety, the new prefabricated concrete assemble beam-column joints can be regarded as the rigid joints; the design formula adopted by the standard of concrete joint classification is theoretically derived, thereby providing a theoretical basis for the new prefabricated concrete structure.

• Steel and Composite Structures
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• 제28권1호
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• pp.73-82
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• 2018

This paper experimentally and analytically elucidates the shear behavior and shear bearing capacity of partially prefabricated steel reinforced concrete (PPSRC) columns and hollow partially prefabricated steel reinforced concrete (HPSRC) columns. Seven specimens including five PPSRC column specimens and two HPSRC column specimens were tested under static monotonic loading. In the test, the influences of shear span aspect ratio and difference of cast-in-place concrete strength on the shear behavior of PPSRC and HPSRC columns were investigated. Based on the test results, the failure pattern, the load-displacement behavior and the shear capacity were focused and analyzed. The test results demonstrated that all the column specimens failed in shear failure mode with high bearing capacity and good deformability. Smaller shear span aspect ratio and higher strength of inner concrete resulted in higher shear bearing capacity, with more ductile and better deformability. Furthermore, calculation formula for predicting the ultimate shear capacity of the PPSRC and HPSRC columns were proposed on the basis of the experimental results.

• 대한건축학회논문집:계획계
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• 제35권1호
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• pp.29-35
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• 2019

The unit modular system is a type of prefabricated construction method that completes the building by uniting the modular units on site by transporting the unit module structure manufactured in the factory to the site. Since the unit module structure is not only the frame but also the finished form including the inner and outer materials, it is most likely to be brought into the field. Therefore, not only the damage of the inner and outer materials but also deformation of frame structure due to the vibration generated during the transportation of the vehicle, And it is necessary to take appropriate methods when transporting the module structure. However, there are no methods to prevent modular structure damage due to vehicle vibration in domestic and foreign modular transportation guidelines or standards. In this study, we investigate the vibrations during the vehicle transportation of the module structure through the road driving test, identify the vibration frequency characteristics of the vehicle through FFT analysis, and propose a vibration reduction methods for module transportation.

• Structural Engineering and Mechanics
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• 제73권6호
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• pp.613-620
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• 2020

The research study is focuses on a form of all-bolted joint with the external ring stiffening plate in the prefabricated steel structure. The components are bolted at site after being fabricated in the factory. Six specimens were tested under cyclic loading, and the effects of column axial compression ratio, concrete-filled column, beam flange sub plate, beam web angle cleats, and spliced column on the failure mode, hysteretic behavior and ductility of the joints were analyzed. The results shown that the proposed all-bolted joint with external ring stiffening plate performed high bearing capability, stable inflexibility degradation, high ductility and plump hysteretic curve. The primary failure modes were bucking at beam end, cracking at the variable section of the external ring stiffening plate, and finally welds fracturing between external ring stiffening plate and column wall. The bearing capability of the joints reduced with the axial compression ratio increased. The use of concrete-filled steel tube column can increase the bearing capability of joints. The existence of the beam flange sub plate, and beam web angle cleat improves the energy dissipation, ductility, bearing capacity and original rigidity of the joint, but also increase the stress concentration at the variable section of the external reinforcing ring plate. The proposed joints with spliced column also performed desirable integrity, large bearing capacity, initial stiffness and energy dissipation capacity for engineering application by reasonable design.

• Computers and Concrete
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• 제22권3호
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• pp.327-336
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• 2018

Increase in population and its daily increasing in our today society results in an increase in housing demand while traditional methods are not applicable. The project preparation and realization processes, based on theoretical and empirical studies, a creation of goods, services, and technologies, are the most important human activities. Selection of effective technological systems in construction is a complex multi-criteria decision-making task. Many decision-makers refuse innovations once faced with similar difficulties. Therefore, using modern materials and methods in this industry is necessary. Modern methods increase quality and construction speed in addition to decrease energy consumption and costs. One of the problems in the way of any project is selecting construction system compatible with the project needs and characteristics. In the present research, different concrete structures such as common reinforced concrete (RC) structure, prefabricated, Insulating Concrete Formwork (ICF), 3D Panel and Tunnel Concrete Formwork (TCF) for buildings with limited floors in Iran are studied and compared from the viewpoint of different criteria like cost, time, applicability and technical characteristics with industrialization approach. Therefore, some questionnaires filled out by construction industry experts in order to compare criteria and sub-criteria in addition to evaluation of optimized structural systems. Then, results of the questionnaires ranked by Analytic Hierarchy Process (AHP) and the most effective alternative selected. The AHP results show that 3D Panel system 36.5%, ICF 21.7%, TCF 19.03%, prefabricated system 13.3% and common RC system 9.3% are the most and the least efficient systems respectively.

• Steel and Composite Structures
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• 제21권5호
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• pp.981-997
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• 2016

To avoid the cracks of cast-in-place concrete in shear pockets and seams in the traditional composite beam with precast decks, this paper proposed a new type of prefabricated steel truss-concrete composite beam (ab. PSTC beam) with pre-embedded shear studs (ab. PSS connector). To study the initial cracking load of concrete deck, the development and distribution laws of the cracks, 3 PSTC beams were tested under hogging moment. And the crack behavior of the deck was compared with traditional precast composite beam, which was assembled by shear pockets and cast-in-place joints. Results show that: (i) the initial crack appears on the deck, thus avoid the appearance of the cracks in the traditional shear pockets; (ii) the crack of the seam appears later than that of the deck, which verifies the reliability of epoxy cement mortar seam, thus solves the complex structure and easily crack behavior of the traditional cast-in-place joints; (iii) the development and the distribution laws of the cracks in PSTC beam are different from the conventional composite beam. Therefore, in the deduction of crack calculation theory, all the above factors should be considered.

• 한국건축시공학회지
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• 제15권6호
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• pp.631-639
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• 2015

유닛모듈러 공법에서는 정밀 제작된 유닛모듈과 시공정밀도가 낮은 기초부의 접합부에서 수평 정밀도 차이가 발생한다. 이러한 정밀도 차이로 인하여 상부 유닛모듈이 뒤틀리거나, 간격이 벌어지는 등 다양한 문제가 야기될 수 있다. 이러한 배경에서 본 연구는 Pre-Fab 독립기초의 높이조절이 가능한 공법을 개발하는 것을 목적으로 하였다. 이를 위하여 본 연구에서는 볼트와 너트를 이용한 높이조절 공법을 제안하고 시공 상세도와 시공순서를 제시하였다. 그리고 구조 시뮬레이션을 수행하여 구조적 안정성을 확인하였다. 향후 개발된 높이조절 공법의 mock-up 시험, 경제성 분석 등을 실시하여 시공성과 유용성을 검토할 예정이다.

• 한국디지털건축인테리어학회논문집
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• 제11권2호
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• pp.71-81
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• 2011

This research explores about the construction process and provision of Japanese Wooden Houses. Even though Prefabricated Houses appeared during the 1960's and the Platform Construction System during the 1970's, there was still a high demand for Conventional Wooden House, with a high demand by households on their 30's. These features were found in the areas of Hokkaido, Kyushu, Tokyo, and Osaka. Tokyo and capital region accommodate large number of the head offices of companies that produce Platform Construction System houses, and thus supply the largest amount of Platform Construction System houses. In capital region, land prices are so high, that they build houses as 3-Floors or above, and also driven by high cost of house construction, house performances are excellent. The houses of Osaka and Kinki region demonstrate similar characteristics to those of capital region. Osaka is headquartered by a group of head offices of companies that produce prefabricated houses, and thus holds more amount of prefabricated house supply than other regions. This city also shows high cost of house construction no less than capital region, and thus offers outstanding performance of house. In Kyushu, whereas Japanese wooden house building systems are supplied the most, Platform Construction System houses are provided the least in the nation. As this region offers rich amount of forest resources owing to mild humid climate which is ideal for vegetations, the Japanese wooden building systems use the timbers from this region. Hokkaido, a cold region, requires houses that offer outstanding performance of heat insulation. Therefore, Hokkaido shows more supplies of Platform Construction System houses that offers outstanding heat insulation performance. They import the timbers that form the structure framework of Platform Construction System houses from North America.

• 한국구조물진단유지관리공학회 논문집
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• 제22권3호
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• pp.75-83
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• 2018

본 연구에서는 일반 버팀보 공법을 개선한 조립식 버팀보 공법을 적용할 때 구조안정성에 대하여 검토하였다. 굴착단계별 가상의 최대 발생 토압력에 대해 좌굴되지 않도록 충분한 강성을 가지는에 대한 안정성검토를 실시하였다. 고강도 조립식 버팀보 공법은 상부플랜지에 일정한 간격으로 볼트 구멍이 천공되어 있는 공법이다. 구조물의 좌굴해석 결과 안전율은 약 5%정도 증가하였고, 발생응력이 허용응력보다 낮기 때문에 버팀보의 구조 안정성은 확보된 것으로 판단된다. 특히 고강도 버팀보 공법을 적용 시 축방향 압축응력은 약 16% 증가한다. 고강도 버팀보 공법은 공사기간을 단축할 수 있으며 추가 부재를 구매할 필요가 없어 경제적이다.