Performance Of Reinforced Concrete Plane Frame Under The Local Fire

Recently reinforced concrete framed structure is one of the mainstyles of architectural structures in our country. Once fire happens partiallyin framed structure, it maybe collapses or destroys in a certain degree. So itis especially significant to take research on reinforced concrete frame whenfire happens partly in the structural space.Reinforced concrete columns are important components in buildingstructures. It's greatly possible to ruin partial even the whole buildings incase of bearing incapability of reinforced column under fires. In such caseit's possible to suffer from heavy losses and make the restoration andstrengthening work on fired structure more difficult. Therefore, to knowmore accurately about the fire resistant performance of reinforced columnunder fires is very important to fire resistant performance of wholestructures.The main contents of the article are as follows:1. The entire process of reinforced concrete columns under fire issimulated. Some factors affected in fire resisting limits are considered.Some rules about fire resisting capability have been summarized:(1) Ratio of axial compression stress to strength and end restrainsaffect greatly to the fire resisting limits of eccentric compression columnthan that of axial compression columns;(2) As the increasing of eccentricity, the fire resisting limits ofcolumns decrease quickly;(3) The fire resisting limits of columns decrease slowly when theslenderness ratio is smaller than 15, while the fire resisting limits ofcolumns decrease rapidly when the slenderness ratio is larger than 15.2. By simulating and analyzing to reinforced concrete frame structurewhich considering fire occurs on different floors. The rules of variation of deformation and mechanics are generalized as follows:(1) To multilayer reinforced concrete frame structure, the fire resistanttime of entire structure increases as the storey that fire happens rises;(2) Both the axial expansive deformation and lateral deformation ofcolumns in the edge are bigger than that of columns in the middle, and thereason is that the restrains and pressures are relatively weaker;(3) The axial force and bending moment of columns in the edgeincrease largely than that of column in the middle, and the axial force ofbeams in fire are bigger than that of beams not in fire.Through the research, it is shown that edge column is the weakness ofentire structure. Fire resisting methods should be strengthened in structuredesigns.