 Proceedings of Engineering and Technology Innovation , vol. 2, 2016, pp. 11 - 13 11 Fire Resistant Study for Long Span Beams Made of FR 490 Steels In-Kyu Kwon * Department of Fire Protection Engineering, Kangwon National University, Samcheok, Korea. Received 22 February 2016; received in revised form 02 April 2016; accept ed 10 May 2016 Abstract Building could be severely influenced by fire and it can be demo lished so that the ma jor structural ele ments such as columns and beams required to be coated by fire protection materials according to each condition. Especially, a steel fra med building regarded as a weaken structures when the build ing is engulfed with a severe fire condition. Therefore, the fire resistant steel (FR 490) has been developed to improve the stru c- tural properties of an ordinary structural steels at high temperature. Generally, the fire resistance of structural beam built with a structural steel can be measured by horizontal furnace using a standard testing method by each nation’s stand- ard. Ho wever, the real length of the bea m showed the tendency longer than that of the horizontal furnace. Therefore, it is considered more important to know the rea l fire resistant performance of structural bea ms. In this paper, to evaluate the fire resistant performance of long span beams made of the FR 490, the fire engi- neering method is done us ing not only materials properties at high temperatures but a heat transfer, a stress theory. The results showed that as the length of beams are longer, the ma ximu m load bearing capacities at high temperatures are lower and the deflections are increased. Ke ywor ds : FR 490, long span beam, fire re - sistant performance, structural sta- bility at high temperature 1. Introduction When steel fra med buildings are covered with a severe fire, the structural stabilit ies can be damaged and this can cause a progressive co l- lapse. Therefore, a ll most of countries require the prima ry structural elements such as columns, beams, trusses the fire protection according to building situation. In Ko rea, the fire protection depends on the buildings height and use. The way to satisfy the fire protection is divided into two parts. One is to obey the building regulation and standard, the other is to design with an e n- gineering technique. The last one is known to an advanced engineering des ign or a performance based fire design. The na me can be used dif- ferently by nation or by person who uses it. The basic concept of the advanced engineering d e- sign consists of a fire scenario and a structural analysis using mechanical properties and heat transfer theory. Until now, the advanced fire engineering method is known to practice to most of countries but not my country. At now, my country is trying to accept the perfo r- mance-based engineering method in building industry and this paper is one of proces s to do it. In general, the structural steel is known as a weaken materia l when it e xposed to a fire. Be - cause the atomic structure is inclined to recede away as the temperature of it is getting high. Therefore, to protect the normal strength of the structural steel at high temperature situation, a proved thickness of passive fire protective ma - terials should be applied. A FR 490 had devel- oped to lessen the tendency to reduce mechani- cal properties such as yield strength and an elastic modulus at high temperature rather than those of SM 490. The FR 490 has the same mechanica l property as the SM 490 has. The purpose of this study is to evaluate the structural stability of long span beams made of the FR 490 at high temperature using mechanica l propert ies and heat transfer and heat stress analysis. 2. Method The structural stability of long span beam can be measured by vertical furnace in terms of deflection with loading. But the vert ical furnace is fixed with a ma ximu m d imension, 4 meters in length and 3 meters in width. But the size of the *Corresponding aut hor. Email: kwonik@kangwon.ac.kr Proceedings of Engineering and Technology Innovation , vol. 2, 2016, pp. 11 - 13 12 Copyright © TAETI vertical furnace is dependent on each fire facility. Therefore, when the longer bea m is required the fire resistance, the furnace is no longer fun c- tioned. Fro m middle 1900’s, a ca lculation method started fro m European nations based on an engineering development and as a reasonable alternative to furnace test. Until now, Korea didn’t utilize the fire en- gineering method and has used a prescriptive method fro m early 1970’s. Therefore , even though the FR 490 showed a better performance than that of SM 490, the steel construction fie ld not allow the FR 490 as a structural steel. To utilize the better structural steel than SM 490 into the construction market, an analytica l evaluation is conducted using mechanical pro p- erties with long span beams. Applied mechan i- cal properties are shown in Table 1. Table 1 Mechanical properties of FR 490 Properties Temperature (℃) Regression Equation Properties T≤500 Cold value (315 MPa) 500