• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.4
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• pp.29-36
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• 2009

This is a basic experimental study to apply FRP modular box member to a variety of construction structures exposed to flexural strength, such as a slab and a girder. Applying FRP modular box member to a real structure requires a large section. FRP box member was made into modular systems. Tests were conducted under various conditions in order to analyze jointing performance of the developed FRP modular box member as a large section. For the methods of jointing FRP modular box member, synthetic resins connection, mechanical connection, and a combination of both were used to test both length and breadth connection. As a result of the test, using urethane + two bolts + sheets was the most efficient method of connecting FRP modular box member. It is expected that the proposed joint system in this study will contribute to the increase of failure load and synthesis behavior of FRP modular box member.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.571-578
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• 2022

Modularization in a high-rise building is different from a small building, as it is exposed to more lateral forces like wind and earthquakes. The integrity, robustness, and overall stability of the modules and their performance is based on the joining techniques and strong structural systems. High lateral stiff construction structures like concrete shear walls and frames, braced steel frames, and steel moment frames are used for the stability of high-rise modular buildings. Similarly, high-rise stick-built buildings have concrete cores and perimeter frames for lateral load strength and stiffness. Methods for general steel-concrete connections are available in many works of literature. However, there are few modular-related papers describing this connection system in modular buildings. This paper aims to review the various research and practice adopted for steel-to-concrete connections in construction and compare the methods between stick-built buildings and modular buildings. The literature review shows that the practice of steel module-to-concrete core connection in high-rise modular buildings is like outrigger beams-to-concrete core connection in stick-built framed buildings. This paper concludes that further studies are needed in developing proper guidelines for a steel module-to-concrete core connection system in high-rise modular buildings.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.19-28
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• 2018

Key factors that ensure competitiveness of modular unit include consistent high quality and connection condition that ensures high structural performance while minimizing the overall scale of the on-site process. However, it is difficult to evaluate the structural performance of the connection of modular unit, and its structural analysis and design method can be different depending on the connection to its development, which affects the seismic performance of its final design. In particular, securing the seismic performance is the key to designing modular systems of mid-to-high-rise structure. In this paper, therefore, the seismic performance of the modular system with bracket-typed fully restrained moment connections according to stiffness and the shapes of various connection members was evaluated through experimental and analytical methods. To verify the seismic performance, a cyclic loading test of the connection joint of the proposed modular system was conducted. As a result of this study, theoretical values and experimental results were compared with the initial stiffness, hysteresis behavior and maximum bending moment of the modular system. Also, the connection joint was modeled, using the commercial program ANSYS, which was then followed by finite element analysis of the system. According to the results of the experiment, the maximum resisting force of the proposed connection exceeded the theoretical parameters, which indicated that a rigid joint structural performance could be secured. These results almost satisfied the criteria for connection bending strength of special moment frame listed on KBC2016.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.45-52
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• 2023

Modular construction is an economical and efficient construction that reduces time and costs by manufacturing units in factories and constructing them on site. Currently, the demand for modular construction is increasing not only abroad but also domestically. As the demand for modular construction increases, a lot of development and research on connections between modular units are being conducted. Connections between modular units should be quick and simple to assemble when assembling units on site, and should be in a form that allows each unit to be connected regardless of direction. In addition, it must be able to exert sufficient strength against external loads. In this study, a connection between modular units using connecting steel plates and bolts was proposed, and the nonlinear behavior of the connection to external lateral force was analyzed through finite element analysis, and resistance performance was evaluated.

• Steel and Composite Structures
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• v.31 no.3
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• pp.217-232
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• 2019

Modular steel buildings consist of prefabricated room-sized structural units that are manufactured offsite and installed onsite. The inter-module connections must fulfill the assembly construction requirements and soundly transfer the external loads. This work proposes an innovative assembled connection suitable for modular buildings with concrete-filled steel tube columns. The connection uses pretensioned strands and plugin bars to vertically connect the adjacent modular columns. The moment-transferring performance of this inter-module connection was studied through monotonic and cyclic loading tests. The results showed that because of the assembly construction, the connected sections were separated under lateral bending, and the prestressed inter-module connection performed as a weak semirigid connection. The moment strength at the early loading stage originated primarily from the contact bonding mechanism with the infilled concrete, and the postyield strength depended mainly on the tensioned strands. The connection displayed a self-centering-like behavior that the induced deformation was reversed during unloading. The energy dissipation originated primarily from frictional slipping of the plugin bars and steel strands. The moment transferring ability was closely related to the section dimension and the arrangements of the plugin bars and steel strands. A simplified strength calculation and evaluation method was also proposed, and the effectiveness was validated with the test data.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.37-44
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• 2017

Due to structural characteristics, construction costs and duration of a modular system would be saved by minimizing the schedule on the job site. As such, it is crucial to develop a connection that can guarantee stiffness while allowing for simple assembling. Particularly, the mid- to high-rise construction of the modular system necessitates the securing of the structural stability and seismic performance of multi-unit frames and connections, and thus, the stiffness of unit-assembled structures needs to be re-evaluated and designed. However, evaluating a frame consisting of slender members and reinforcing materials is a complicated process. Therefore, the present study aims to examine the structural characteristics of a modular unit connection based a method for reinforcing connection brackets and hinges while minimizing the loss of the cross section. Toward this end, the study modeled the beam-to-column connection of a modular system with the proposed connection, and produced a specimen which was used to perform a cycling loading test. The study compared the initial stiffness, the attributes of the hysteretic behavior, and the maximum flexural moment, and observed whether the model acquired the seismic performance, compared to the flexural strength of the steel moment frame connection that is required by the Korean Building Code. The test results showed that the proposed connection produced a similar initial stiffness value to that of the theoretical equation, and its maximum strength exceeded the theoretical strength. Furthermore, the model with a larger ceiling bracket showed higher seismic performance, which was further increased by the reinforcement of the plate.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.455-463
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• 2010

This is a basic experimental study to apply FRP modular box member to a variety of construction structures exposed to flexural strength, such as a slab and a girder. Tests were conducted under various conditions in order to analyze jointing performance features of the developed FRP modular box member as a large section. For the methods of jointing FRP modular box member, chemical connection, mechanical connection, and a combination of both were used to test both vertical and horizontal jointing. As a result of the test, using urethane+two bolts+sheets was the most efficient method of connecting FRP modular box member, and confirmed the efficient behavior by a finite element analysis.

• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.69-76
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• 2021

Precast concrete (PC) modules have been increased its use in modular buildings due to their better seismic performance than steel modules. The main issue of the PC module is to ensure structural performance with appropriate connection methods. This study proposed a PC modular beam system for simple construction and improved structural and splicing performance. This modular system consisted of modules with steel plates inserted, and it is easy to construct by bolted connection. The steel plates play the role of tensile rebar and stirrup, which has the advantage of structural performance. The structural performance of the proposed PC modular beam system was evaluated by flexural test on one reinforced concrete (RC) beam specimen consisting of a monolithic, and two PC specimens with the proposed PC modular beam system. The results demonstrated that the proposed PC modular beam system achieved approximately 86% of the structural performance compared to the RC monolithic specimen, with similar ductility of approximately 1.06 fold greater.

• Steel and Composite Structures
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• v.37 no.3
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• pp.273-289
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• 2020

Due to the unique construction method of modular steel buildings (MSBs) with units prefabricated fully off the site and assembled quickly on the site, the inter-module connection for easy operation and overall performance of the system were key issues. However, it was a lack of relevant research on the system-level performance of MSBs. This study investigated the seismic performance of two-storey modular steel structure with a proposed vertical rotary inter-module connection. Three full-scale quasi-static tests, with and without corrugated steel plate and its combination, were carried out to evaluate and compare their seismic behaviour. The hysteretic performance, skeleton curves, ductile performance, stiffness degradation, energy dissipation capacity, and deformation pattern were clarified. The results showed that good ductility and plastic deformation ability of such modular steel structures. Two lateral-force resistance mechanisms with different layout combinations were also discussed in detail. The corrugated steel plate could significantly improve the lateral stiffness and bearing capacity of the modular steel structure. The cooperative working mechanism of modules and inter-module connections was further analyzed. When the lateral stiffness of upper and lower modular structures was close, limited bending moment transfer may be considered for the inter-module connection. While a large lateral stiffness difference existed initially between the upper and lower structures, an obvious gap occurred at the inter-module connection, and this gap may significantly influence the bending moments transferred by the inter-module connections. Meanwhile, several design recommendations of inter-module connections were also given for the application of MSBs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.6
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• pp.427-435
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• 2020

Modular structures are relatively lightweight compared to reinforced-concrete or steel structures. However, it is difficult to achieve structural integrity between the columns of unit modules in a modular structure, which causes undesirable effects on the lateral force resistance capacity against wind and earthquake loads. This is more prominent in modular structures whose overall heights are greater. Hence, a post-tensioned modular structural system is proposed herein to improve the lateral force resistance capacity of a typical modular structure. A post-tensioned column-base connection, which is the main component of the proposed modular structural system, is configured with shapes and characteristics that allow inducing self-centering behaviors. Finite element analysis was then performed to investigate the hysteretic behaviors of the post-tensioned column-base connection. The analysis results show that the hysteretic behaviors are significantly affected by the initial tension forces and beam-column connection details at the base.