• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.92-99
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• 2011

Ultra High Performance Concrete(UHPC) is a superior structural material with high strength and durability. Construction of light and slim structures is realized to apply this expectable new materials in practice. This research is a part of the project to develop UHPC precast deck system for hybrid cable stayed bridge. The main object of this study is to investigate behavior of the lap-spliced reinforced connection in UHPC. The major parameter considered in experimental plan was lap-spliced length. The 4-points bending test for 12 specimens were conducted to verify the effect of considered parameters. Test results show that the minimum value of lap spliced length of 300mm which specified in current korea high bridge design code was very conservative for UHPC precast deck system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.1-8
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• 2018

The object of this paper is to find the characteristics of fire proof materials through an analytical method and to suggest a proper approach for fire-proof design of reinforced concrete beam strengthened with fiber reinforced polymer (FRP). Heating tests for fire-proof materials were conducted and the thermal conductivities and specific heats of them were simulated through finite element analyses. In addition, a finite element analysis on the beam specimen strengthened with FRP under high temperature, which was conducted by previous researchers, was performed and the analytical result was compared with test result. And then the compatibility of the analytical approach was evaluated. Finally, the heat resistance characteristic of RC beam strengthened with FRP was analyzed by the proposed analytical method and the strength decrease of the beam due to the high temperature was evaluated. From the comparison with analytical and test result, it was found that the heat transfer from outside to inside through the fire-proof materials can be suitably simulated by using the proposed analytical approach.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.44-54
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• 2012

The structural designs of RC flat plates that have no flexural stiffness by boundary beams may be governed not by strength conditions but by serviceabilities. Specially, since over-loading and tensile cracking in early-aged slabs significantly increase the immediate and long-term deflections of a flat plate system, a construction sequence and its impact on the slab deflections may be decisive factors in designs of flat plate systems. In this study, the procedure of calculating slab deflections with considering construction sequences, concrete cracking, and long-term effects is proposed. Using the proposed method, the parametric study for deflections of flat plates is performed. With various conditions for slab construction cycle, the number of shored floors, tensile or compressive reinforcement ratio, compressive strength of concrete, construction live load, and slab thickness, the immediate deflection during construction and long-term deflections after completion are analyzed. The calculated results are compared with the serviceability limits offered by the structural design code.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.463-472
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• 2007

This paper presents theoretical and finite element analysis results for the lateral-torsional buckling of I-girders with corrugated web under uniform bending. Lateral-torsional buckling is a major design aspect for flexural members composed of thin-walled I-section. However, torsional rigidities such as the warping constants of the I-girders with corrugated web are not fully understood yet. In this paper, bending and pure torsional rigidities of I-girders with corrugated web are first described using the results of previous researchers. Then, the location of the shear center and the warping constants are derived. Using the derived section properties of I-girders with corrugated web, the lateral-torsional buckling strength is determined. Finite element analyses are conducted and the proposed lateral-torsional buckling strength of I-girders with corrugated web is successfully verified. Finally, the effects of corrugation profiles of the web on the lateral-torsional buckling load of I-girders with corrugated web are discussed.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.483-492
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• 2007

Pre-Engineering Building (PEB) system is one of the most economical structural systems. Tapered members can resist a maximum stress at a single location, whereas stresses of the rest of the members are considerably low. This results in appreciable savings both in terms of materials and construction costs. However, it was appreciated that special consideration would be required for certain aspects of this structural form. In particular, because of their slenderness, webs would buckle laterally and torsionally under the combined action of excessive axial, bending and shear forces. In this study, a total of four large-scale rafters with simple ends were tested. The main parameters were the width-thickness ratio of the web, the stiffener, and the flange brace. The purpose of this experiment is to evaluate the structural stability and to offer back-data on PEB design.

• Journal of Korean Society of Steel Construction
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• v.25 no.2
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• pp.153-164
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• 2013

In this paper, lateral-torsional buckling(LTB) strength of HSB800 high strength steel plate girder with monosymmetric section under uniform moment was evaluated by nonlinear analysis. The unbraced length in inelastic LTB range was considered for the sections whose smaller or larger flange is in compression with slender, noncompact and compact web. Analyses of SM490 steel girders were first performed with the single-panel and three-panel model to judge the validity of the constructed models by comparing those results with Eurocode 3, AASHTO and AISC codes. By using the same models, LTB strength of HSB800 girder was evaluated and it was found that the sections whose smaller flange is in compression with noncompact flange-slender/noncompact web could not reach the flexural strength of the design codes.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.4
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• pp.195-205
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• 2015

Various non-seismic tie details are frequently used for one- and two-story small buildings because the seismic demand on their deformation capacities is not relatively significant. To evaluate the effects of the non-seismic tie details on the seismic performance of reinforced concrete columns, six square columns with a cross section of $400{\times}400mm$ and six rectangular columns with a cross section of $250{\times}640mm$ were tested. The anchorage details at both ends and spacing of tie hoops, along with the cross-sectional shape and the magnitude of axial load, were considered as the primary test parameters. Test results showed that square columns had higher stiffness and lower lateral deformation rather than rectangular columns. Both lap spliced tie and U-shaped tie provided comparable or improved seismic performance to $90^{\circ}$ hook tie in terms of maximum strength, ductility, and energy dissipation. The predicted curves with modeling parameters in ASCE41-13 were conservative for test results of lap spliced tie and U-shaped tie specimens since plastic behavior after flexural yielding could not be considered. For economical design, ASCE41-13 should be revised with various test results of tie details.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.465-477
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• 2020

This paper presents an investigation on the dynamic behavior of SRC columns with built-in cross-shaped steels under impact load. Seven 1/2 scaled SRC specimens were subjected to low-speed impact by a gravity drop hammer test system. Three main parameters, including the lateral impact height, the axial compression ratios and the stirrup spacing, were considered in the response analysis of the specimens. The failure mode, deformation, the absorbed energy of columns, as well as impact loads are discussed. The results are mainly characterized by bending-shear failure, meanwhile specimens can maintain an acceptable integrity. More than 33% of the input impact energy is dissipated, which demonstrates its excellent impact resistance. As the impact height increases, the flexural cracks and shear cracks observed on the surface of specimens were denser and wider. The recorded time-history of impact force and mid-span displacement confirmed the three stages of relative movement between the hammer and the column. Additionally, the displacements had a notable delay compared to the rapid changes observed in the measured impact load. The deflection of the mid-span did not exceed 5.90mm while the impact load reached peak value. The impact resistance of the specimen can be improved by proper design for stirrup ratios and increasing the axial load. However, the cracking and spalling of the concrete cover at the impact point was obvious with the increasing in stiffness.

• Computers and Concrete
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• v.10 no.1
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• pp.1-18
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• 2012

This paper presents the details of studies conducted on hollow concrete block masonry (HCBM) units and wall panels. This study includes, compressive strength of unit block, ungrouted and grouted HCB prisms, flexural strength evaluation, testing of HCBM panels with and without opening. Non-linear finite element (FE) analysis of HCBM panels with and without opening has been carried out by simulating the actual test conditions. Constant vertical load is applied on the top of the wall panel and then lateral load is applied in incremental manner. The in-plane deformation is recorded under each incremental lateral load. Displacement ductility factors and response reduction factors have been evaluated based on experimental results. From the study, it is observed that fully grouted and partially reinforced HCBM panel without opening performed well compared to other types of wall panels in lateral load resistance and displacement ductility. In all the wall panels, shear cracks originated at loading point and moved towards the compression toe of the wall. The force reduction factor of a wall panel with opening is much less when compared with fully reinforced wall panel with no opening. The displacement values obtained by non-linear FE analysis are found to be in good agreement with the corresponding experimental values. The influence of mortar joint has been included in the stress-strain behaviour as a monolith with HCBM and not considered separately. The derived response reduction factors will be useful for the design of reinforced HCBM wall panels subjected to lateral forces generated due to earthquakes.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.3
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• pp.208-215
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• 2011

A full-scale field trial in ice-covered sea is one of the most important tasks in the design of icebreaking ships. The first Korean icebreaking research vessel 'ARAON', after her delivery in late 2009, had a sea ice field trial in the Arctic Sea during July-August, 2010. This paper describes the test procedures and data analysis on the icebreaking performance of the IBRV ARAON. The data gathered from the icebreaking performance test in the Chukchi Sea and the Beaufort Sea during the Arctic voyage of ARAON includes the speed and engine power of the ship as well as sea ice thickness and strength data. The air temperature, wind speed and heading of the ship were also measured during each sea ice trial. The ARAON was designed to break 1 m thick level ice with a flexural strength of 630kPa at a continuous speed of 3knots. She is registered as a KR POLAR 10 class ship. The principal dimensions of ARAON are 110 m, 19 m and 6.8 m in length, breadth and draft respectively. She is equipped with four 3,500kW diesel-electric main engines and two Azipod type propulsion motors. Four sea ice trials were carried out to understand the relationship between the engine power and the ship speed, given the Arctic ice condition. The analysis shows that the ARAON was able to operate at 1.5knots in a 2.5m thick medium ice floe condition with the engine power of 5MW, and the speed reached 3.1 knots at the same ice floe condition when the power increased to 6.6MW. She showed a good performance of speed in medium ice floe compared to the speed performance in level ice. More detailed analysis is summarized in this paper.