In-Rak Choi

Hysteresis Model of Thin Infill Plate for Cyclic Nonlinear Analysis of Steel Plate Shear Walls

A hysteresis model for thin infill steel plates was developed to evaluate the nonlinear cyclic behavior of steel plate shear walls. Nonlinear finite-element analysis was performed for thin steel plates with a rigid boundary frame. Based on the analysis results, the hysteretic behavior of the infill steel plate was simplified as an equivalent uniaxial stress-strain relationship in the direction of tension-field action. The proposed hysteresis model was implemented in macroscopic analysis models for infill steel plates, i.e., the tension strip model and equivalent tension brace model. The proposed method was applied to existing test specimens with various design parameters and loading conditions. The prediction results were compared with the test results.

Cyclic Loading Test for Reinforced Concrete Frame with Thin Steel Infill Plate

An experimental study was performed to investigate the cyclic behavior of walls that are composed of reinforced concrete boundary frames and thin steel infill plates. For this purpose, three-story steel plate infilled walls (SPIW) were tested. The parameters in this test were the reinforcement ratio of the columns and opening in the infill plates. A reinforced concrete infilled wall (RCIW) and a reinforced concrete frame (RCF) were also tested for comparison. The deformation capacity of the SPIW specimens was significantly greater than that of the RCIW specimen, though the specimens exhibited an identical load-carrying capacity. Similar to the steel plate walls with steel boundary frames, the SPIW specimens showed excellent strength, deformation capacity, and energy dissipation capacity. Furthermore, by using the steel infill plates, shear cracking and failure of the column-beam joints were prevented. By using the strip model, the strength and initial stiffness of the SPIW specimens were predicted. The pr...

Concrete-Filled Steel Tube Columns Encased with Thin Precast Concrete

AbstractAn experimental study was performed to investigate the axial-flexural load-carrying capacity of concrete-filled steel tube columns encased with thin precast concrete (PC). Six eccentrically loaded columns and one concentrically loaded column were tested. To prevent the premature failure of the concrete encasement, various reinforcement details such as studs, steel fiber, welded wire mesh, and cross ties were used. The maximum axial loads of the specimens agreed with the strengths predicted by current design codes, although in some specimens, the load-carrying capacity decreased immediately after the peak strength owing to early spalling of the concrete encasement. On the basis of the test results, the use of fiber-reinforced concrete is recommended to increase the ductility of columns by restraining the spalling of the concrete encasement.

Eccentric Axial Load Test for High-Strength Composite Columns of Various Sectional Configurations

AbstractComposite columns of various sectional configurations are studied to maximize the contribution of high-strength steel under compression-flexural loading. For concrete-encased steel (CES) co...

An Analysis of Design Formulas on Section Types of Rectangular Concrete Filled Steel Tube Columns

The purpose of this study is to analyze the axial load capacity equations for rectangular CFT columns in the AISC 360-10 (the US design code for structural steel buildings) which is being investigated as a revision of Korean Building Code. Main parameters were the width-to-thickness ratios of composite member and material strength as 30~100MPa of concrete compressive strength and 325~725MPa of yield strength of structural steel. The first method of changing width-to-thickness ratios was to fix the thickness of structural steel to 5mm and to increase the size of member. The second method was to fix the size of member to and to change the thickness of structural steel. The analysis results indicated that axial load capacity used higher strength steel is lower than the capacity used lower strength one in some regions although the section size was equal. The reason of this result is due to the different section type that is classified by the equation of limit width-to-thickness ratios. When the yield strength of structural steel become higher, its section type and axial load capacity equation is changed though its width-to-thickness ratio is the same with the lower yield strength members. The region of this phenomenon is become wider following to the increase of concrete compressive strength because part of concrete load capacity is govern the total load capacity of members. To resolve this irregular phenomenon that axial load capacity is reversed in some region, it is necessary to modify the code provision for calculation the load capacity in high strength materials.