Soo Yeon Seo

Physical Characteristic of Ready Mixed Concrete with Different Replacement Ratio of Recycled Aggregate

Researches until now about recycled aggregate have mainly focused on illuminating physical properties and mechanical behaviors of recycled aggregate by experimenting on small batches of mixing. Unfortunately this kind of mixing does not necessarily fit the reality where a large amount of ready-mixed concrete is often made. Therefore, this study carried out an experiment by having a ready-mixed concrete manufacturing company mix a large amount of recycled aggregate that satisfies quality standard set by the MCT of Korea, then verifying the behaviors of recycled aggregate concrete. The target concrete compressive strength was selected as 24MPa had a slump flow for 120±25mm and air content of 5.0±1.5%, that is used most in site. The main experiment variable of this study is to replacement ratio of recycled aggregate(RA). The 27 test specimens were designed with recycled aggregate replacement ratio that had range of coarse recycled aggregate(CRA), 0, 10, 20, 30, 40, and 50%. The result shows that replacing the natural aggregate with the recycled one up to the ratio of 30% satisfies the quality standard for mixing concrete properly.

Polycarbonate Daylighting Performance on the Top-Lit Building

This study evaluates the daylighting performance of a polycarbonate as a substitute for glass on top-lit buildings. For the study, the polycarbonate types and properties are analyzed and simulation tests are performed based on DF(daylight factor, %). As results, 16mm flat-plated, saw-blade and the diamond-type polycarbonate window are recommended as substitutes for window glasses. Also, when developing the polycarbonate as the top-lit buildings, it is advisable to apply the saw-blade and diamond-types to establish the direction of development.

Structural Behavior of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforcement Polymer Plate

This paper presents the study to find retrofit effect in case of Near-Surface-Mounted Retrofit (NSMR) using Carbon Fiber Reinforcement Polymer (CFRP) plate targeting reinforcement concrete (RC) beam by comparing the previous Externally Bonded Retrofit (EBR) method through experimental analytical works. Three RC beam specimens were made and two of them were retrofitted with CFRP plate by using EBR and NSMR. Also Finite Element (FE) analysis was performed in order to simulate the structural behavior of the beams by considering the bond properties between concrete and CFRP. From the study, it was found that the beam retrofitted with EBR hada reduction of bond capacity in the joint while the beam retrofitted with NSMR had perfect bond capacity.

FE Analysis on the Structural Behavior of Reinforced Concrete Beam Damaged by Fire

This paper presents an analytical result about strength deterioration of reinforced concrete (RC) beams due to damage by fire. For the evaluation of the result, three RC beam specimens were made and two of those were exposed to fire. And then beam test was performed for those including non-heated specimen to evaluate the strength deterioration due to the fire damage under simple support condition. Strength decrease of materials due to the fire was evaluated through material test for concrete and reinforcements, respectively. Nonlinear Finite element (FE) analysis was performed by considering the decrease of materials due to fire. The analysis results showed that the structural behavior of fire-damaged RC beam was able to be simulated by using FE analysis with consideration of the reduction of material capacity due to fire.

Strength, Stiffness and Energy Dissipated Characteristics of Reinforced Concrete Coupling Beams with Diagonal Headed-Bars

This paper investigated the strength, peak-to-peak stiffness and energy dissipated capacity of coupling beam with diagonal headed-bars. Test variable included the replacement ratios of diagonal headed-bars. The results show that specimens HB 30, and HB 50 using headed bars for concrete confinement sustained corresponding peak-to-peak stiffness and cumulative dissipated energy in comparison to specimen CON.

Hysteretic Behavior of Reinforced Concrete Coupling Beams with Diagonal Headed-Bars

This paper addresses the seismic behavior of coupling beams with headed reinforcing bars in coupled shear wall system. Test variable included the replacement ratios of headed reinforcing bars. The results show that Specimen HB 50 exhibits a better stable behavior in comparison with Specimens Specimen CON and Specimen HB 30. Test results showed that the amount of diagonal reinforcing bars in the coupling beam may be reduced when headed reinforcing bars are utilized.

The Effect of Alternative Reinforcement Details in Reinforced Concrete Coupling Beams

In this study, a design alternative for reinforced concrete (RC) coupling beamswith diagonal headed-bars that puts less reliance on diagonal reinforcement wasexperimentally investigated. The results show that specimen HB 50 exhibits a better stable behavior incomparison with specimens CON and HB 30. Test results showed that specimens HB75 with replacement ratio of 75 % diagonal headed – bars were efficient inresisting high shear load.

Effect of Axial Compression in the Basement Composite Beam Controlled by Flexure

In the newly developed excavation system for construction of basement of building, steel elements plays a role as temporary member before casting floor concrete, but it do behavior as composite beam mixed with concrete after floor slab has been casted. That is, it is necessary to review if axial stress loaded in steel beam can be conveyed properly to slab, as casting concrete slab under conditions of application of compression to the steel beam In this manner, this paper presents the experimental result of the composite beam subjected to both constant axial load and variable vertical load. Main parameters in the test are magnitude and loading time of axial force. As a result, it was found that there was no effect on the flexural strength according to the timing of compression and axial force. The flexural strength of the composite beam subjected to both a constant axial compression and increasing vertical load could be predicted with somewhat safety by using code equations.

Tensile Capacity of Mechanical Bar Connection Corresponding to Detail of Screw on Bar Surface for Construction

This study is intended to investigate the performance depending on the screw type at the end part of reinforcement in the mechanical connection of high strength reinforcement with screws. Three types of mechanical connection were designed and tensile test was performed for those. The results presented that, although the end part of reinforcement was processed with screws, the reinforcement’s yield and tensile strength sufficiently appeared. But, its plastic deformation capacity after yielding fell 17~26% more than reinforcement.

Seismic Capacity of Reinforced Concrete Frame Strengthened with In-Filled Wall Using Embedded Form

This study includes the development of the seismic retrofit technology that structural frame of building is strengthened by installing additional wall with embedded form after demolition of the inner walls of unreinforced masonry wall including the exterior design walls. In addition, this paper involves the earthquake resistant performance evaluation of the system through an experimental work. From the test, it was turned out that as for the maximum strength of the specimens, the maximum load was similar regardless of whether using the embedded form. However, EF-IW-H1(embedded form) specimen with the form hardware embedded in the wall during retrofit resulted in ductile behavior of the, which shows the effect on the embedded form in a sense.