• Structural Engineering and Mechanics
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• 제62권5호
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• pp.567-576
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• 2017

Structural failures are undesirable events that devastate the construction industry resulting in loss of life, injury, huge property loss, and also affect the economy of the region. Roof truss failures occur mainly due to excessive loading, improper fabrication, deterioration, inadequate repair, etc. Although very rare, a roof truss may even fail due to inappropriate location of supports. One such case was reported from the recent failure of a steel roof truss used in an indoor stadium at Kargil in India. Kargil region, being mountainous in nature, receives heavy snowfall and hence the steel roof trusses are designed for heavy snow loads. Due to inappropriate support location, the indoor stadium's steel roof truss had failed under heavy snow load for which it was designed and became an interesting structural engineering problem. The failure observed was primarily in terms of yielding of the bottom chord under the supports, leading to partial collapse of the roof truss. This paper summarizes the results of laboratory tests and analytical studies that focused on the validation of the proposed remedial measure for rehabilitating this distressed steel roof truss. The study presents the evaluation of (i) significant reduction in strength and stiffness of the distressed truss resulting in its failure, (ii) desired recovery in both strength and stiffness of the rectified truss contributed by the proposed remedial measure. Three types of models i.e., ideal truss model, as build truss model and rectified truss model were fabricated and tested under monotonic loading. The structural configuration and support condition varied in all the three models to represent the ideal truss, distressed truss and the rectified truss. To verify the accuracy of the experimental results, an analytical study was carried out and the results of this analytical study are compared with the experimental ones.

• 한국공간구조학회논문집
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• 제16권2호
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• pp.89-96
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• 2016

Cable structures are lightweight structures of flexible type, cable members have only axial stiffness related to tension, they can carry neither bending nor compression. This study is the analysis of cable truss systems are composed of upper and low cables by connecting bracing cables, the structural principle is based on a tensegrity system by using bracing tension members, discontinuous compression members and continuous tension members. A hanging roof of cable truss system is too flexible against vertical loads, most cable members are stabilized by connecting the prestressed upper and lower cable by bracing cables. A cable truss roof system is formed by adding a set of cables with reverse curvature to the suspension cables. With the sets of cables having opposite curvature to each other, cable truss is able to carry vertical load in both upward and downward direction with equal effectiveness, and then a cable truss acts as load bearing elements by the assemble of ridge cables, valley cables and bracing cables. This paper will be shown the geometric non-linear analysis result of cable truss systems with various sag ratio for deflections and tensile forces, the analytical results are compared with the results of other researchers.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2001년도 학술대회지
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• pp.214-221
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• 2001

인천국제공항 교통센터의 Great Hall은 3차원의 입체적 곡면 Truss로 구성되어 있고, Great Hall Roof Truss는 최대 경간162m, 480Ton인 Truss을 포함한 13개의 Main Steel Truss로 구성되어 있다. Great Hall Roof Truss는 총 중량 6,300Ton, 9,600 Pieces로 1개의 절점당 최대 13개의 다른 부재가 접합하게 되어 있고, 12개의 Fabric 기초에 의해 지지된다. 경제적인 효과와 공기적 측면을 고려하여 기존 재래식(가설 Bent) 공법보다 Block화 공법 및 Sliding공법을 채택하였다. Roof 구조물은 3,550Ton과 2,700Ton 중량인 두 Block으로 나누고 구조물 외부에 설치 된 Giant Sleigh에 선 조립 후 Tandem Pulling Jack과 Strand를 이용하여 181m를 Sliding하여 본 구조물의 위치에 설치되었다.

• Structural Engineering and Mechanics
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• 제29권1호
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• pp.37-53
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• 2008

Plane steel portal frames, with pitched roof, exposed to fire, are examined. First, a determinate frame is analysed by hand. For flexible columns and shallow roof, snap-through occurs before plastic hinges mechanism is formed. An indeterminate frame with shorter columns and taller roof is also analysed by hand. Then, the same frame is simulated by a truss and a nonlinear static analysis is performed by use of a short computer program. The results of computer analysis by use of truss model are compared with those of analysis by hand and a satisfactory approximation between them is observed.

• Steel and Composite Structures
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• 제37권4호
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• pp.463-479
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• 2020

Currently, there are many lateral resisting systems utilized in resisting lateral loads being produced in an earthquake. Such systems can significantly reduce the roof's displacement when placed at an optimum location. Since in the design of tall buildings, the minimum distance between adjacent buildings is important. In this paper, the critical excitation method is used to determine the best location of the belt truss system while calculating the minimum required distance between two adjacent buildings. For this purpose, the belt truss system is placed at a specific story. Then the critical earthquakes are computed so that the considered constraints are satisfied, and the value of roof displacement is maximized. This procedure is repeated for all stories; i.e., for each, a critical acceleration is computed. From this set of computed roof displacement values, the story with the least displacement is selected as the best location for the belt truss system. Numerical studies demonstrate that absolute roof displacements induced through critical accelerations range between 5.36 to 1.95 times of the San Fernando earthquake for the first example and 7.67 to 1.22 times of the San Fernando earthquake for the second example. This method can also be used to determine the minimum required distance between two adjacent buildings to eliminate the pounding effects. For this purpose, this value is computed based on different standard codes and compared with the results of the critical excitation method to show the ability of the proposed method.

• 한국강구조학회 논문집
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• 제15권5호통권66호
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• pp.519-529
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• 2003

최근에 스틸하우스나 고층아파트 지붕에 경량형강 지붕트러스의 사용이 증가하는 추세이다. 그러나 현재 지붕트러스와 하부구조의 앵커 접합부의 설계는 거의 경험에 의존하는 실정이다. 본 논문에서는 냉간성형형강 지붕트러스 앵커 접합부의 구조적인 거동에 관한 실험적인 연구를 서술하였다. 트러스부재와 접합철물은 스크류로 접합하였으며, 하부구조의 구조재료에 따라 시공성 및 구조적인 성능이 우수한 단순한 형태의 접합철물을 사용하여 철근콘크리트구조인 경우 케미컬 앵커볼트 그리고 강구조인 경우는 용접 및 DX-Pin을 사용하여 하부구조와 연결하였다. 다양한 접합부 형태에 대한 인발실험을 수향하여 접합부의 강도 및 강성을 측정하였으며, 이를 AISI시방서(1996) AISC시방서(1989)규정에 근거한 설계강도와 비교하였다. 또한 스크류 연결부의 최대전단강도식을 제안하여 실험결과와 비교하였다.

• Structural Engineering and Mechanics
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• 제8권2호
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• pp.165-180
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• 1999

The cost effectiveness of using steel roof systems for residential buildings is becoming increasingly apparent with the decrease in manufacturing cost of steel components, reliability and efficiency in construction practices, and the economic and environmental concerns. While steel has been one of the primary materials for structural systems, it is only recently that its use for residential buildings is being explored. A comprehensive system for the design of residential steel roof truss systems is presented. In the first stage of the research the design curves obtained from the AISI-LRFD code for the manufactured cross-sections were verified experimentally. Components of the truss systems were tested in order to determine their member properties when subjected to axial force and bending moments. In addition, the experiments were simulated using finite element analysis to provide an additional source of verification. The second stage of the research involved the development of an integrated design approach that would automatically design a lowest cost roof truss given minimal input. A modified genetic algorithm was used to handle sizing, shape and topology variables in the design problem. The developed methodology was implemented in a software system for the purpose of designing the lowest cost truss that would meet the AISI code provisions and construction requirements given the input parameters. The third stage of the research involved full-scale testing of a typical residential steel roof designed using the developed software system. The full scale testing established the factor of safety while validating the analysis and design procedures. Evaluation of the test results indicates that designs using the present approach provide a structure with enough reserve strength to perform as predicted and are very economical.

• Steel and Composite Structures
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• 제1권1호
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• pp.17-32
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• 2001

The Rosette-joining system is a completely new press-joining method for cold-formed steel structures. One Rosette-joint has a shear capacity equal to that of approximately four screws or rivets. The Rosette thin-walled steel truss system presents a new fully integrated prefabricated alternative to light-weight roof truss structures. The trusses are built up on special industrial production lines from modified top hat sections used as top and bottom chords and channel sections used as webs which are joined together with the Rosette press-joining technique to form a completed structure easy to transport and install. A single web section is used when sufficient but can be strengthened by double-nesting two separate sections or by using two lateral profiles where greater compressive axial forces are met. An individual joint in the truss can be strengthened by introducing a hollow bolt into the joint hole. The bolt gives the connection capacity a boost of approximately 20%. A series of laboratory tests have been carried out in order to verify the Rosette truss system in practice. In addition to compression tests on individual sections of different lengths, tests have also been done on small structural assemblies and on actual full-scale trusses of a span of 10 metres. Design calculations have been performed on selected roof truss geometries based on the test results, FE-analysis and on the Eurocode 3 and U.S.(AISI) design codes.

• 한국공간구조학회논문집
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• 제17권2호
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• pp.21-32
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• 2017

The objective of this study is to analysis the mechanical characteristics on the geometric nonlinear behavior of radial cable roof systems for long span retractable cable roof structures. The retractable roof is designed as a full control system to overcome extreme outdoor environments such as extreme hot or cold weather, strong wind or sunlight, and the cable roof greatly can reduce roof weight compared to other rigid structural system. A retractable cable roof system is a type of structures in which the part of entire roof can be opened and closed. The radial cable roof is an effective structural system for large span retractable roofs, the outer perimeter of the roof is a fixed membrane roof and the middle part is a roof that can be opened and closed. The double arrangement cables of a radial cable truss roof system with reverse curvature works more effectively as a load bearing cables, the cable system can carry vertical load in up and downward direction. In this paper, to analyze the mechanical characteristics of a radial cable roof system with central posts, the authors will investigate the tensile forces of bearing cables, stabilized cables, ring cables, and the deflection of roof according to the height of the post or hub that affects the sag ratio of cable truss. The tensile forces of the cables and the deflection of the roof are compared for the cases when the retractable roof is closed and opened.

• 건축역사연구
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• 제20권4호
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• pp.95-114
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• 2011

Western style timber roof trusses used as typical roof structures of buildings during a modern period have been developed with the interactions with their facade and functionality. The shapes of trusses and member sizes have been diversely changed by the purposes of architects, historical circumstances, and structural characteristics. For this reason, the change in the shapes of western style timber trusses along the times is one of important technology assets demonstrating the development of their structures during the modern period. Therefore, the purpose of this paper is to find out their structural characteristics throughout parametric analysis of which parameters were determined from the collected and classified documents on western style timber roof structure built in the modern period carefully obtained from public institutions. Results of the parametric analysis are as follows. The number of king-post trusses and modified king-post trusses built between 1920 and 1937 reaches almost half of the total number of truss types investigated. The mean values of their spans, distances, tributary areas, and height are respectively, 10.5m, 2.4m, $24.37m^2$and 3.24m. The cross-section areas of trusses tend to reduce since the city construction law was enacted in 1920. Also, this study found that western architects usually used larger structural members than eastern architects and usages and finishing materials of roof trusses are not always considered as one of the important design parameters.