Verification of the Seismic Performance of a Rigidly Connected Modular System Depending on the Shape and Size of the Ceiling Bracket

Abstract

Modular systems have been mostly researched in relatively low-rise structures but, lately, their applications to mid- to high-rise structures began to be reviewed, and research interest in new modularization subjects has increased. The application of modular systems to mid- to high-rise structures requires the structural stability of the frame and connections that consist of units, and the evaluation of the stiffness of structures that are combined in units. However, the combination of general units causes loss of the cross-section of columns or beams, resulting in low seismic performance and hindering installation works in the field. In addition, the evaluation of a frame considering such a cross-sectional loss is not easy. Therefore, it is necessary to develop a joint that is stable and easy to install. In the study, a rigidly connected modular system was proposed as a moment-resisting frame for a unit modular system, and their joints were developed and their performances were compared. The proposed system changed the ceiling beam into a bracket type to fasten bolts. It can be merged with other seismic force-resisting systems. To verify the seismic performance of the proposed system, a cyclic loading test was conducted, and the rigidly connected joint performance and integrated behavior at the joint of modular units were investigated. From the experimental results, the maximum resisting force of the proposed connection exceeded the theoretical parameters, indicating that a rigid joint structural performance could be secured.

Simplified Modelling of Novel Non-Welded Joints for Modular Steel Buildings

“…6 shows the lateral bending capacity of joints. The procedure for determining the bending capacity of each joint was identical to that reported previously [17,28,31,32]. The developed joints were found to have a significantly higher lateral load-carrying capacity and seismic response than previously proposed joints [41,42].…”

“…The seismic performance of each joint model was evaluated using the special moment frame (SMF) parameters, which were found to be consistent with the 0.04 rad rotational deformation capacity with a strength of 0.8MP [28,40]. All corner joint models met the drift angle accumulation criteria of 0.04 rad and the required bending moment capacity (except S3 with a 0.92 ratio).…”

“…It is evident that the majority of previous studies identified joints for cold-formed or C-sections or joints that required access holes in columns or beams to operate bolt screwing, resulting in a weakened cross-section or joints unable to connect interior modules. Similarly, most studies concentrated primarily on the lateral performance of corner frames and the development of simplified models for them, ignoring the actual performance of middle and interior joints, as well as the rotational stiffness of intermodular joints [28][29][30]. Furthermore, the majority of simplified models were capable of simulating joint elastic behaviour without accounting for elastic-plastic performance.…”

Perceptions towards risks involved in off-site construction in the integrated design & construction project delivery

“…The second highest ranked risk item according to RII values calculated in Table 3 is DR5 (i.e., insufficient design code for joints between prefabricated components). It has been emphasized and evaluated in multiple studies (e.g., Kim et al, 2017;Lee et al, 2017;Park et al, 2017) of the connection joints between modular members. In contrast, the two general risk items (i.e., GR1 and GR2) were perceived as least likely to occur among the 14 risk items.…”

Numerical Studies on the Seismic Behaviour of a Prefabricated Multi-Storey Modular Steel Building With New-Type Bolted Joints

“…investigated the bearing capacity of a full-scale modular unit under vertical and lateral loadings by using means of tests and FE analysis [28]. The studies previously recorded were found to be confined to the performance of corner joints, simplified frames or modular units without any proper detailed behaviour of connections, use of weaker sections and access holes, while, very least attention was paid to the behaviour of complex form of joints, i.e., middle joint, simplification of the joint to overcome computational efforts, combined effect of forces on the behaviour of modular units with the developed joint and the overall dynamic response of MSB against real earthquake accelerograms [8,24,25,27,29,30]. The main aim of the current study was to develop a newtype of bolted joint, analyse its bending performance, simplify and apply it in the full-scale modular units, and evaluate the overall seismic performance of the developed simplified multi-storey MSB.…”