Flexible self-locking intermodular connection for prefabricated modular steel buildings
The modular building uses factory-built 3D or room-sized volumetric modules. They assemble on site as the building's key structural elements. Compared to conventional construction, modular constructions are different in detailing requirements, construction method, structural performance, and...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104059/1/FK%202022%2086%20IR.pdf http://psasir.upm.edu.my/id/eprint/104059/ |
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| Summary: | The modular building uses factory-built 3D or room-sized volumetric modules. They
assemble on site as the building's key structural elements. Compared to conventional
construction, modular constructions are different in detailing requirements, construction
method, structural performance, and load-transfer mechanism. In conventional steel
structures, the structural members have a high degree of connectivity, whereas in
modular construction, the modules are connected at their corners only by inter-modular
connections (IMC), and these connections are the most vulnerable points of failure. In
the connecting region, numerous small beams and columns meet together, which poses
new challenges to structural design. Currently, the inter-modular connections are pinned
connections, which are provided in the form of a connection plate and a high-strength
bolt. An access hole in the column is provided for the erection of the bolt, which causes
cross-sectional loss of the column and is unfavorable for the “strong column-weak beam”
seismic design concept, leading to unfavorable failure mechanisms which can threaten
the entire structure. This study proposed a self-locking connection to address these issues
of IMCs. The proposed connection uses a simple mechanism of spring to be fixed, does
not require extra workspace between modules, and is suitable for interior, exterior, and
corner joints. Proposed connection comprises of upper and lower adapters, flat spring,
spring pin, center plate and middle plate the center plate and adapter are welded together;
the flat spring is free at the one end to move, while it is fixed through welding at other
end. The adjacent module in internal as well as exterior joint are connected by middle
plate. The middle plate is positioned on top of the upper adaptor, the upper adaptors are
inserted through square spaces providing on middle plates. Dowel pins are provided at
each corner of the center plate to allow for the alignment of the modules that are joined
to the middle plate during assembly. The distance between floors beam as well as the
ceiling beam is similar as total thickness of middle plates and the center plate. This
interconnection will transfer the primary failure locations away from important structural
parts like columns and provide adequate seismic load stress mitigation. The connection
components can be fabricated off-site and assembled on-site. Finally, this would result
in a multistory modular building structure entirely manufactured off-site and assembled
as a full-frame capable of withstanding gravity and lateral loading. Experimental tests were performed to verify and analyze the strength and the predicted ductile failure pattern
of the newly proposed inter-modular connections. The details of the test specimens were
selected based on a six-story modular residential building design; a height of 3m and
width of 3.6m of the module was considered. T- shaped specimens were fabricated to
simulate the corner joint of MSB; half of the original height and width of a module was
adopted presuming that beam and column inflection points coincide at the center length
of the member. Under monotonic and cyclic load, three full-scaled specimens were tested
to compare the joints' mechanical behaviour. Extensive numerical studies were carried
out utilizing established methodologies for finite element modeling to investigate and
compare the proposed connections in terms of seismic response and slip mechanisms
with those of a standard inter-modular connection currently used in steel modular
buildings. Finite element models were discretized by employing the appropriate mesh
elements. Due to the higher accuracy, all parts were modelled with brick elements
(hexahedral) For steel modelling a nonlinear steel behavior signified by bi-linear stressstrain
relationship was considered. Furthermore, the surface-Surface technique was
employed to define property between bolt shank, bolt hole and surfaces of the plates.
Parametric sensitivity analyses were conducted to determine the parameters and the
components that influence the performance and failure mechanisms of the proposed
connection. The experimental and finite element analyses show that the proposed
intermodular connections have better seismic behavior across a range of response
characteristics, including moment-carrying capacity, energy dissipation capacity, and
ductility. The ductile failure patterns were observed among beams, with no severe plastic
deformations in critical structural components like columns or joints. The findings
provide ideas for the design and analysis of intermodular connections that meet the
requirements of entirely modular buildings. This research will lead to considerable
improvements in the dynamic response and life safety of modular structures subjected to
lateral loads in general and seismic loads in particular. |
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