RESEARCH

Novel Structure

Buckling Restrained Brace for Diagrid Structural System

To develop the buckling resistance of the main brace for the diagrid structural system, which can be adopted for the recent tall buildings, a new buckling restrained brace for the diagrid system will be proposed and verified by the test and analysis. A numerical analysis model of the diagrid BRB structural system is proposed, and it is compared with the result of the frame test to evaluate the efficiency of the analysis model and structural performance of Diagrid BRB depending on the size of the tube’s slot-hole, a joint detail used for frame experiment is evaluated using finite element analysis.


Fire Resistance Performance of Steel–Polymer Prefabricated Composite Floors Using Standard Fire Tests

The iFLASH System is a prefabricated synthetic floor member filled with an eco-friendly phase change material (PCM) with strong adhesion between upper and lower steel plates. The iFLASH System's main features can divided into weight reduction, floor height reduction, time reduction, eco-friendliness, explosion-proof and vibration-resistance performance, and fire resistance performance.


Hemisphere-Shaped Iron Joint between PHC Pile and Steel Reinforced Concrete Column.

Cast-In-Place (CIP) concrete pile methods are used for top-down construction, such as PRD (Percussion Rotary Drill), RCD (Reverse Circulation Drill), and All casing methods, large-scale construction storage yard, curing periods of concrete material (elongates a construction period), and using stabilizer liquid harmful to the environment is inevitable. Also, it is hard to guarantee a uniform construction quality of concrete piles. To use PHC piles in top-down construction, which can overcome the disadvantages of using CIP concrete piles, a joint design that connects a PHC pile to a column is the most critical. In particular, the joint of the PHC pile to the column properly transfers the axial stress from a column to a PHC pile without punching shear effects and stress concentration. Large local strains at the joint of the PHC pile to the column must be prevented to ensure adequate rigidity between them. In this study, the first develop 16 prototypes of the joint of the PHC pile to the column from basic domed-shape geometry, which is advantageous in saving materials compared to an arch-shaped joint of the PHC pile to the column under compression. With the commercial software ABAQUS, the structural behaviors of each prototype are analytically investigated for the worst case, which is under a compression load of 1.5 times the capacity of a PHC pile (Diameter 1000mm pile’s axial strength is 967tonf[5], so we compressed 1500tont). The most effective prototype is suggested for further experimental study based on the analytical results we studied.


Design and construction technologies of underground columns using the 1,000ton class HAT Joint

To overcome the disadvantages of usual Cast-In-Place(CIP) concrete pile methods in top-down or up-up construction, some prototypes of a joint between the PHC pile and column are analytically studied. We used the FEM analysis program(ABAQUS) to find the optimal shape. Considering the strength requirement and stress concentration of the joint of the PHC pile to the column, we suggest the most appropriate prototype. The new joint is named the HAT(Hollow hAlf-sphere sTeel) joint, which can transfer load only for compression. We did a structure performance test to check the analysis results. After developing the new joint, it was constructed instead of a CIP pile for the Pilot Project. Usually, construction methods like CIP piles take time to cure the basement. However, the HAT Joint can help construct the upper area before curing. It can be an effective way to reduce construction period and cost.


Development of ES2 System for Construction Energy Reduction

Merits of SRC columns, which are used frequently for buildings, are energy saving for construction, improvement of construction ability, the convenience of erection, and shortening of the construction period. Despite its many advantages, the SRC column has difficulty integrating because it uses composite materials such as steel and concrete. Also, SRC makes construction complicated by the additional process. To solve the problem, a new concept of a high-strength composite column system that keeps the advantages and makes up for the weakness of the SRC column is necessary. This research develops details of the ES2(Energy Saving Structural) column system that combines fabrication factory concrete (PC) and cast-in-place concrete(RC) by replacing the steel part of the SRC column with PC and verifies internal structural force experimentally. We also developed joint and steel beams to apply the ES2 column system in the construction field.