Kang Min Lee

Insulation Type Effect on the Direct Shear Behavior of Concrete Sandwich Panel (CSP) with Non-Shear Connectors

Precast concrete sandwich panels (PCSP) are often used as exterior cladding of residential buildings due to thermal efficiency. PCSP systems consist of two precast reinforced concrete walls separated by a layer of insulation and connected with connectors which penetrate the insulation layer and are anchored at two precast walls. This paper provides the pull-out test results of concrete sandwich panel (CSP) with non-shear connectors. The variables in this study were the casting direction of reinforced concrete walls and types of insulation. Test results indicated that the types of insulations and casting direction have a significant effect on the bond strength between concrete wall and insulation. The effect of insulation type is notable for CSP cast horizontally concrete walls.

Seismic Analysis of Concrete Conical Foundation for 5 MWWind Turbine

Recently offshore wind turbines have been constructed and planned in Korea. However, seismic stability was not extensively examined, although relatively small earthquakes frequently occur and the occurrence trend is increasing. This study intends to analyze the seismic stability of a wind turbine foundation based on KPMDC, KBDC, and DNV OS. The foundation considered has a conical concrete base under a steel shaft supporting the 5 MW wind turbine. This study performed 3D response spectrum analysis to consider turbine weight and self-weights. Analysis resultsbased on KPMDC indicatedthat very severetensile stresses in the concrete foundation near the neck bracket and pile-concrete foundation connection, which may require reinforcing.

Analytical Study on Steel Plate Reinforcement Effect at Beam-Column Joints in Reinforced Concrete Frame

This paper analyzed the reinforcement effect of concrete beam-to-column joints bonded with steel plate in reinforced concrete structures using finite element program. The limit load, ductility, and cracks of unreinforced model and reinforced model by steel plates were evaluated based on the analytical variations of reinforced steel plate area and thickness. As a result of analytical study, the maximum load of reinforced model by steel plate has 63% to 97.5% against unreinforced model. Also, to increase steel plate thickness has better performance than when steel plate area increases.

Analysis Study on Axial Force in Bolted Connection under Fatigue Load

High-strength bolted connection is widely used for steel structure construction. Because high-strength bolted connection has simple constructability and structural qualification. Especially friction type with high-strength bolted connection has high stiffness and fatigue strength. At this time, initial clamping force is one of main factor to affect the strength and deformation behavior of connection. Therefore, the objective of this study is to investigate reduction of initial clamping force in high-strength bolted connection under fatigue load. And the parameter of this study is the size of the bolt and 3 types of initial clamping force. The analysis is used the finite element analysis program ANSYS Workbench.

An Experimental Evaluation of Structural Performance for High Strength Steel Stub Columns under Eccentric Loads

The researches on strength of members bending-compression were evaluated through experimental tests on eccentrically load of high-strength steel (HSA800). This test was performed on H-shaped steels of high strength steel (HSA800) to verify the P-M correlations of members subjected to combined forces according to axial load ratios. And this strength evaluation test was performed for various P-M combinations on adjusted eccentric distance. The results showed that all the specimens was satisfied with P-M correlations according to design criteria.

Structural Performance Evaluation of Built-Up Stub Steel Column with Various Steel Grades under Concentric Loading

The current local stability criteria (KBC2009, AISC2010) are enacted through theoretical and experimental studies of ordinary steels, but the mechanical properties of high strength steels are different from ordinary steels. The high strength steel in the applicability of design criteria should be needed to review because of increasing market demanding for high strength steel in the high-rise and long span buildings. In this study, stub columns of H-shaped and box section with various steel grades subjected to concentric loading were investigated, and these steels were checked to the applicability of current local stability criteria. The difference between the ordinary steel and high strength steel was compared. As a result of comparison with various steel grades, most specimens were satisfied with the design criteria, but some specimens with lower tensile strength were not reached the required strength. It is considered that the uncertainty of material was the higher when the tensile strength of material was the lower.

Compressive Testing of H-Shaped Steel Stub Columns Fabricated with Grade 800MPa High Performance Steel

With the increased demand for high-rise and long-span structures, high strength with high performance steels have been utilized for these kind of structures. For the grade 800MPa high performance steel, although it was included in Korean Standard as high strength steel(HSA 800), however the HSA 800 steel was excluded in Korean Building Code-Structures due to the rack of research results for the structural behaviors of members fabricated with HSA 800 steel. Therefore, this paper describes basic study for the design specification of structural members using HSA 800 high performance steel. For this purpose, welded H-shaped stub column specimens with various width-to-thickness ratios were designed and tested in order to investigate the buckling behaviors and ultimate compressive strength.

Joint Displacement Evaluation of a Modular Road System

Transportation agencies have recently been struggling to carry out rapid roadway construction and repair work with minimal disruption to the motoring public, and they are pursuing sustainable and perpetual roadway systems with minimal maintenance over their service life. This study sought to develop a roadway joint system as a part of research on a sustainable-perpetual-modular (SPM) roadway system. In this study, two boundary conditions were considered with varying support offsets. Dead load, live load, and temperature load were considered and the corresponding displacements were computed. Roller supports at both ends produced larger displacements compared to hinge supports at both ends. Analysis results exhibited that a support offset equal to 0.0 m produced the smallest displacement. The results of this study will provide valuable information for the design of modular roadway joint systems.

Effects of Different Bolted Connection Types on Seismic Performance of Column-Tree Steel Moment Connections

This paper experimentally presents the effects of different bolted connection types on the seismic performance of column-tree steel moment connections used in moment resisting frames. Two full scale test specimens were fabricated and tested: one specimen with slip critical bolted beam splices and the other one with bearing type bolted beam splices. The bearing type splice specimen was expected an improved deformation capacity by means of bolt slippage. The experimental results showed that the slip critical splice specimen successfully developed ductile behavior without brittle fracture until 5% story drift ratio, however for the bearing type splice specimen, the beam bottom flange fractured at 4.0% story drift ratio due to stress concentration around the weld access hole area. However the energy dissipation capacity of the bearing type splice specimen was better than that of the slip critical splice specimen until 4.0% story drift ratio.

Local Buckling Behaviors of Built-Up Box Columns Fabricated with High-Performance Steel under Concentric Axial Loading

Recently, high-performance steel has been increasingly used for structural materials in buildings and bridges with the demand for high-rise and long-span of main structures. This paper is a series of basic study for the design specification of structural members using high performance steel, material properties of HAS800(High-performance rolled Steel for building structures). HSA800 was compared with the requirements of Korean Standards(KS). Built-up box stub columns with variables of width-to-thickness ratios are planned in order to investigate the local buckling behaviors and check the current design limit of width-to-thickness ratio. In addition, the buckling behaviors of stub columns obtained finite element analysis were compared with those of test results.