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This paper discusses the development of a new structural composite hybrid system that is able to replace a conventional residential structural system in which space is partitioned using concrete walls. The new structural system consists of structural tees and wide flange steel beams, with the bottom flange and/or portion of the web partially encased in pre-cast concrete, which is then mechanically anchored by headed stud shear connectors both to the bottom flange and the web of the structural tees. In composite frame built apartments, materials known to be heavy carbon dioxide (CO2) emitters can then be either excluded or reduced with consequent reduction in CO2 emissions. This study has investigated 36 selected multi-residential apartment buildings of linear shape to compare the CO2 emissions of the new composite hybrid and conventional multi-residential apartments. The CO2 emissions resulting from the composite hybrid apartments were reduced to approximately 75—80% in comparison to the emissions occurring from the construction of conventional load-bearing wall apartments. This was achieved by reducing the main sources responsible for CO2 emission.

Summary This paper proposed a precast concrete‐based dry mechanical joint for fully‐restrained moment connections which can be used to connect reinforced concrete precast columns. In the proposed connections, a pair of steel plates is provided and connected by high‐strength bolts to transfer axial loads and moments. One plate is installed at the bottom of upper columns, and another one is placed on the top of lower columns. The stiffness of the column plates is determined to enable axial loads and the moment to be transferred at joints, providing a fully‐restrained moment connection between columns. The structural behavior of the moment connections was evaluated through experimental and analytical investigations. Through extensive experimental investigations, columns jointed with plates capable of sufficient stiffness and strength demonstrated structural behavior similar to those of conventional columns. The plate deformations which fail to transfer the moment were not prevented with columns jointed by plates incapable of providing sufficient stiffness and strength. A good match in terms of the load–displacement relationship and plate deformation was also demonstrated between the finite element analysis based prediction and the test data for all specimens. The introduced connections will contribute to modular offsite construction for buildings and heavy industrial plants.

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Apartments with load-bearing wall construction are used extensively in Korea, but have the disadvantage of a short life, causing serious economic losses in terms of construction waste, materials and energy consumption. This paper presents the findings on multi-residential apartments that utilise a hybrid composite frame as a viable alternative for the energy efficiency associated with construction materials. The hybrid composite frame consists of a structural tee, reinforcement steels and pre-cast concrete. The use of the hybrid composite frame reduces the overall amount of energy consumption. In addition, multi-residential apartments utilising a hybrid composite frame have advantages such as flexibility in planning and easier repair and remodelling. This study investigates tower-shape, multi-residential apartments of various heights and floor areas to compare the energy efficiency of the hybrid composite system with that of the bearing wall system. The multi-residential apartments that utilise the hybrid composite frame are analysed in terms of both reduced principal materials and reduced energy consumption compared with apartments of a load-bearing wall structure. Rapid demand for long life and multi-residential apartment construction is expected.

Summary This paper proposes dry mechanical beam–column joints for fully restrained moment connections of concrete components. This novel joint can be used for reinforced concrete precast frames and steel–concrete composite precast frames. The new dry mechanical joint consists of extended steel plates with bolts designed to transfer tension and compression forces, providing fully restrained moment connections at the beam–column joint. The extended end plate with bolts introduced for column‐beam joint assembly was originally used in the steel moment frame, as introduced in AISC 358. This study developed similar but unique mechanical joint details for concrete frames in order to provide fully restrained moment connections for both steel–concrete composite precast frames and reinforced concrete precast frames. Experimental and analytical investigations were performed to verify the structural behavior of fully restrained moment connections for concrete components in order to identify the parameters that influence the structural behavior of dry mechanical moment concrete connections. These connections are expected to be used in modular offsite construction for buildings and heavy industrial plants. Copyright © 2016 John Wiley & Sons, Ltd.

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The authors present an experimental and analytical investigation of the modularized hybrid system (MHS) that utilizes the composite structure described in previous studies, that of a wide steel flange and precast concrete. The objective of this paper was to introduce the application of the MHS structural system to a high‐rise building in which one additional floor was added while the overall building height was maintained. The 68‐m‐tall, 18‐storey steel building was redesigned to a 19‐storey building using the composite beams, which combine the merits of ductile steel and concrete components to withstand external loading while reducing floor height. The bottom flange of the steel beam is reinforced with concrete at a manufacturing plant, eliminating the use of temporary pour forms. The erection process of the composite beams is identical to that of traditional steel construction. This paper also describes more than 30 potential applications of high‐rise composite construction using the MHS frames. The advantages of the MHS are presented in terms of reduced structural steel tonnage and shortened construction schedules. Copyright © 2009 John Wiley & Sons, Ltd.