In-Kyu Kwon

A Study on the Properties of SM 400 for Evaluation of Structural Stability at High Temperature

Recently, the risk of fire outbreak is going up because of newly developed combustible materials are intended to apply more. Especially the steel framed structure can lose its load-bearing capacity when it is exposed to higher temperature condition such as a fire. So the pre-evaluation of fire resistance of the structure is very essential that the mechanical properties of yield strength and elastic modulus and thermal properties such as conductivity and linear expansion be required. To get the databases for SM 400 or welding structural steels at high temperature, various temperature conditions were used for deriving the yield strength, elastic modulus, linear expansion, and conductivity and the results were compared to those of SS 400, ordinary structural steel, respectively.

Evaluation Study on the Mechanical and Thermal Properties of High Strength Structural Steel at High Temperature

Recently, building constructions have been developed toward high-rise, long span, and multi-complexed using the high strength materials, optimized section. But the structural behavior of steel structural members built with a high strength steel at fire condition is not clarified because of lacking of information of related references such as mechanical and thermal properties at high temperature situation. In this paper, to evaluate the structural stability of member or frame of steel framed building at fire situation through the engineering method, the mechanical and thermal experimental coupon tests have conducted at various high temperatures and the comparison to those of ordinary strength steels were done.

An Analytic Study on Structural Stability according to Boundary Conditions and H-section Column Lengths Made of An Ordinary Grade Structural Steels (SS 400) at High Temperatures

강구조 건축물의 기둥부재 내화성능은 접합부의 경계조건과 기둥부재의 길이에 따라 변화되지만, 내화성능 평가는 실험장비의 제약과 기술적 요인으로 인하여 힌지단과 3500 mm 길이 조건으로 이루어지고 있다. 그러나 실제 강구조물에적용되는 기둥부재는 부지조건과 설계조건에 따라 다양한 경계조건과 길이의 변화를 가져올 수 있으며, 이에 대한 내화성능의 평가는 어려운 실정이다. 따라서 본 연구에서는 일반 등급의 구조용 강재(SS 400)로 제작된 H형강 기둥부재를대상으로 고온 시의 재료특성과 해석적 이론을 바탕으로 고온 시 구조적 성능을 평가하여, 경계조건과 길이 변화에 따른내화성능의 기본 자료를 도출하였다.ABSTRACTSteel column is very important an structural element in steel framed building and plays a key role in sustataining theapplied external load. Generally, the fire resistance performance of steel column has been executed by application of firestandard and vertical furnace having a limitation in height. Therefore, the fire resistance test was conducted with a H-sec-tion column having 3500 mm in length and hinge to hinge boundary condition. And the fire protective material derivedfrom the fire test can be applied to any kind of boundary conditions and lengths. However, it is hard to determine the fireresistance. In this paper, to make sure the structural stability of them at high temperature according to various boundaryconditions and lengths of H-section column, an analysis was done by using the mechanical properties and an heat transfertheory.

Experimental Study on Making Databases for Fire Resistant Steel at High Temperature

Fire at building can occur enormous damages to life, properties, and environment and the risk of fire breakout is going up higher because of application of combustible materials than before. Therefore, the steel industries are trying to develop fire resistant steel in order to sustain the load bearing capacity of steel structures during fire situation. In this paper, to give the basis data-bases for evaluation of structural stability of steel structures applied fire resistant steel, FR 490, the tests of mechanical and thermal properties at high temperature were conducted and the comparisons are done with the SM 490 that has the same mechanical one.

Study on Fire Resistance Performance According to Boundary Conditions for Beams Made of High-Strength Structural Steels Using Analytical Methods

건축물의 공간 효율성 증대를 주 목적으로 고강재 강재(SM 520)의 사용이 활성화되고 있으나, 화재와 같은 고온조건에서의 보부재에 대한 내화성능은 검증되지 못하고 있는 실정이다. 따라서 본 연구에서는 SM 520강재가 적용된 양단고정단 경계조건인 부정정 보부재를 대상으로 표준화재온도곡선과 고온에서의 항복강도, 탄성계수 그리고 비열, 선팽창계수를 적용하는 해석적 방법을 통하여 내화성능을 평가하고, 이를 바탕으로 일반 구조용 강재에 의한 보부재의 내화성능 평가의 안전성을 확인하였다.ABSTRACTRecently, structural materials have been developed to have high performance, and SM 520 has been developed andused for high-rise buildings. However, fires frequently occur in buildings, and the number of victims and amount of dam-age increase year by year. However, the evaluation of fire resistance performance for structural beams made of SM 520 isdone with specimens made of ordinary structural steels with boundary conditions of a fixed beam, and the results areallowed for use in steel-framed buildings. This study analyzed the fire resistance performance of statistically indetermi-nate beams built with SM 520. The analysis used a fire engineering technique that includes mechanical and thermal dataof SM 520 and heat transfer theory, and heat stress analysis was also conducted. The results from the analysis were com-pared with those from a statistically determinate beam made of ordinary structural steels.Keywords : High strength steels, SM 520, Fire resistance performance, Fire design

Analytical Structural Stability Evaluation for H-section Beams Made of Ordinary Structural Steels Based on Boundary Conditions at High Temperatures

Loads applied on the floor are transferred through beams to columns. The beams can be designed as both end fixed or simple beams. The load bearing capacity of a beam depends on each boundary condition. However, when the load bearing capacity of a beam is evaluated in fire tests, all kinds of beams are tested using simple beam conditions. In this study, an analytical method performed using heat transfer theory and heat stress analysis based on the mechanical and thermal properties of SS-400 steel at high temperature. This method was used to clarify the differences between the two types of boundary conditions at normal and high temperature. The results show that the load bearing capacity of a both-end fixed beam at high temperature is superior to that of a simple beam. Therefore, the application of simple beam conditions in fire tests for evaluation of load bearing capacity is conservatively safe compared to fixed boundary conditions.

Evaluation of Structural Stability of Fire Resistant Steel Produced by Thermo-Mechanical Control Process at High Temperature

대형화, 초고층 및 고스팬에 부응하기 위한 강재 기술개발의 노력으로 용접성능과 내진성능 그리고 내화성능이 부여된새로운 강재인 Thermo-mechanical control process (TMCP) 내화강재가 개발되었다. TMCP 내화강재는 기존의 내화강재 생산과정 시 압연과 동시에 정밀한 열처리를 병행함으로 인장력과 용접성을 향상시킬 수 있는 새로운 기술인 TMCP방법으로 개발되었으며, 화재와 같은 고온에서의 구조적 안전성에 관한 내력평가가 요구되었다. 따라서 본 연구에서는고온 시 TMCP 내화강재의 내력평가를 목적으로 고온 시 항복강도, 탄성계수를 평가하고 각각에 대한 온도영역별 실험식을 제시하였으며, 이를 일반 내화강재의 고온 특성과 비교, 분석하였다. 또한 각각의 소재로 설정된 H형강 기둥부재를대상으로 고온 시의 내력을 계산하여 그 안전성을 확인한 결과, TMCP 내화강재의 고온 시 내력특성은 일반강 내화강재의 고온 내력저하 특성보다 열위인 것으로 나타났다.ABSTRACTFire resistance steel, grading 490 MPa, had developed by using Thermo-mechanical control process (TMCP) and it hasbetter performance at welding, seismic resistance than those of the ordinary structural steel, But the fire resistance perfor-mance is required to verify against the ordinary fire resistance, FR 490. Therefore this study was done to make databaseof mechanical properties at high temperature and to evaluate the structural stability at high temperature in terms of materi-als and structural member such as H-section from that of FR 490. The result of this study was that the structural stabilityof TMCP was lower than that of ordinary FR 490 at the range up about 700