Seon-Chee Park

Development of Structural Composite Hybrid Systems and their Application with regard to the Reduction of CO2 Emissions

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.

An Assessment of the Energy and Resource-efficient Hybrid Composite Beams for Multi-residential Apartments

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.

Evaluation of the Energy Efficiencies of Pre-cast Composite Columns

Columns manufactured with pre-cast concrete could reduce construction waste and CO2 emissions by reducing the use of temporary materials such as formwork. In this paper, three types of connection methods are introduced. The structural performance of pre-cast composite columns connected to beams was investigated for the column connection. Multi-story pre-cast composite columns could significantly reduce the construction time, resulting in a decrease in CO2 emissions. This paper reports the analysis of the compression and bending of a two-story column so as to verify the structural performances of pre-cast composite columns to provide adequate integrity to ensure a safe environment for building accommodation. In addition, a steel-framed column and a steel-framed reinforced concrete (SRC) column configured to feature the same compression performance as a pre-cast composite column were designed on the basis of the analysis results. The CO2 emissions and energy efficiency of the composite columns were compared with those of conventional steel and SRC columns during the design and construction phases. This paper also presents new composite columns providing efficient energy consumption with reduced CO2 emissions for a more environmentally conscientious construction of buildings.

An Assessment of CO2 Emission of the Structural Composite Hybrid Beam Based on Strain Compatibility

Structural composite hybrid beams consist of a rolled wide-flange steel shaped to allow the bottom flange and/or a portion of the web of the steel section partially encased in pre-cast concrete. For each limit state, a series of plastic strain distributions corresponding to a particular location of the neutral axis and stresses in the reinforcing steel and steel section was assumed. For the assumed strain distributions, equations were derived based on equilibrium equations and solved for the neutral axis and stress levels in the concrete block, the reinforcing steels and the steel section. The calculated stress levels in the structural components were compared with the assumed stresses obtained from the assumed strain distribution. The strain compatibility approach allows for analytical calculations that correlate well, thus avoiding the need for complex and tedious calculations of the flexural moment capacity for complex structures. In this work, Green Beam and steel beam with the same flexural moment capacity were compared and the ability of the Green Beam to reduce CO 2 emissions was demonstrated.

Investigation of the Energy Efficiency and CO2 Emission Characteristics of Pre-stressed Composite Beams

In this work, the energy efficiency and CO2 emission characteristics of a pre-stressed steel-framed reinforced concrete composite beam were investigated for application in high rise apartment buildings. The beam consisted of pre-cast and cast-in-place concrete with a structural T at the end section of the pre-cast concrete. As a result, CO2 emissions were significantly reduced by decreasing the quantity of steel. The composite beams were tested which demonstrated acceptable structural performance as flexural members. The measured flexible strengths of the pre-stressed composite beams were compared with the calculated flexural strengths based on the strain compatibility approach in the yield limit state and maximum load limit state. Good agreement between the experimental and analytical flexural capacities was observed. The application of the pre-stressed composite beams capable of enhancing energy efficiencies while decreasing CO2 emissions could provide a safe structure for a comfortable built environment and will be of great benefits to the welfare of a community as well. This work demonstrates that reduced CO2 emissions can be achieved by introducing pre-stressing in a concrete composite beam and by installing a structural T only at the end of the composite beam.

Reduction Effect of Toxic Substances for Apartment Buildings with an Ecofriendly Pre-cast Composite Structural System

Concrete, one of the construction materials used for apartment buildings, emits some toxic substances including CO2 and chromium VI that are detrimental to occupants. This paper presents pre-cast composite beams with T-type steels at each end to reduce the use of concrete. The new structural system is developed to replace the bearing walls of conventional apartment buildings. The pre-cast composite beams of the new concept (which can be used for apartment buildings) provide similar floor depth while minimizing the use of concrete materials. The CO2 and chromium VI emissions estimated from apartment buildings constructed with bearing walls are compared with those from buildings designed with the proposed composite beams. The data obtained from the previous study of Hong et al. [Hong WK, Kim JM, Park SC, Lee SG, Kim SI, Yoon KJ, Kim HC, Kim JT: A new apartment construction technology with effective CO2 emission reduction capabilities: Energy Int J 2010;35(6):2639–2646; Hong WK, Park SC, Kim JM, Kim SI, Lee SG, Yune DY, Yoon TH, Ryoo BY: Development of structural composite hybrid systems and their application with regard to the reduction of CO2 emissions: Indoor Built Environ 2010;19(1):151–162] for the amount of concrete material in the apartment buildings was used to estimate the amounts of CO2 and chromium VI emissions. The pre-cast composite beams of the new concept are believed to be an effective structural system to reduce the use of concrete material, which in turn reduces the amounts of the noxious materials, CO2 and chromium VI. The new healthy structural frame system introduced in this paper shows the potential to enhance the health of occupants.

Mathematical model of hybrid precast gravity frames for smart construction and engineering

The structural stability, constructability, economic feasibility, environmental-friendliness, and energy efficiency of hybrid composite frame systems have been demonstrated by practical application and research. A hybrid composite frame system combines the economy of precast concrete structures with the constructability of steel frame structures, including erection speed. Novel composite frames will ultimately maximize the efficiency of structural design and facilitate construction. This paper presents hybrid precast frames, which are precast composite frames based on a simple connection between precast concrete columns and beams. The hybrid precast frames designed to resist gravity loading consist of PC columns, PC beams, and steel inserted in the precast members. Steel sections located between the precast columns were simply connected to steel inserted at each end of the precast beams. Dynamic analysis of a 15-story building designed with the proposed composite frame was performed to determine the dynamic characteristics of a building constructed of hybrid frames, including frequencies and mode shapes.

Application of Smart Frames to tall buildings with dual systems and with building frame systems

This paper investigates the suitability and environmental friendliness of using hybrid pre-cast composite structural systems for use in apartment buildings. The hybrid pre-cast composite structural system was utilized in one apartment building. The application propriety and environmental friendliness of hybrid pre-cast composite structural systems were verified by comparison with a flat plate, reinforced concrete Rahmen frame. The hybrid pre-cast composite structural systems presented in this study can be used as a lateral Smart Frame and a gravity Smart Frame. The lateral Smart Frame with moment connections is used for dual systems, in which the moment frames should be able to resist at least 25% of the seismic design forces. Gravity Smart Frames with pin joints for building frame systems are essentially complete space frames providing supports for vertical loads. Seismic force resistance is provided by shear walls. The hybrid pre-cast composite structural system demonstrated its application propriety by its ability to reduce the quantity of construction material. According to the structural design results with hybrid pre-cast composite structural systems, less material was required per unit area compared with the flat plate and reinforced concrete Rahmen frame structures. This structural system can thus reduce CO2 emissions and energy consumption, helping to preserve the environment.

Environmentally-Friendly Apartment Buildings Using a Sustainable Hybrid Precast Composite System

Recently, as part of an effort to comply with the low-carbon green growth policy adopted in Korea, the building of new long-life apartment buildings has been encouraged to replace existing apartment buildings with bearing walls. The regulations imposed regarding floor area ratios, height, and available sunlight can all be alleviated when apartment buildings are built using the Rahmen structural frame instead of conventional bearing walls, which are difficult to remodel. However, a Rahmen structural frame with reinforced concrete increases the floor height due to the increased beam depth, resulting in economic issues. This paper introduces a hybrid precast composite structural system. Apartment buildings optimized using the hybrid precast composite Rahmen structural system was compared with concrete Rahmen structural frames. The results show that the lower material quantity used in the hybrid precast composite structural system reduces carbon emissions and as well as energy inputs related to construction. It is expected that the hybrid precast composite Rahmen structural system will play a significant role in building sustainable and healthy long-life apartment buildings.