STUDY ON BEHAVIOUR OF STRENGTH OF COMPOSITE COLUMN CONSISTED OF H-SHAPE STEEL AND LIGHT-WEIGHT CONCRETE UNDER AXIAL FORCE

This paper was intended to bring forward the studies made on an analysis of how the compression can be apportionately taken care of by the composite column consisted of structural steel and light-weight concrete when the compression is transmitted from the steel beam fireproofed by non-concrete materials. Although there is a probability of stress transmission from the flange of beam to concrete element of the composite column, it is considered negligible from the point of the general practice when we take into account of settlement of concrete and also of difficulty that is usually brought about in finishing concrete surfaces between such place. Thus the studies have been solely directed toward finding out the effect of the compression in cases that the total shearing stresses of beam is directly transmitted to structural steel of the composite column, and a series of experimental compression tests had been carried out using specimens of one-piece steel column of H-shape with full web and those of one-piece steel column of H-shape with ribs to its flanges and web, which are fabrcated specifically for the purpose of obtaining better bondage between concrete and steel. The results of the said tests coupled with stress measurements revealed that steel column of H-shape with ribs has much higher integrity in bond than that without ribs by comparision when it is encased in concrete. Again, when the compressive stresses are transmitted from the structural steel beam to structural steel column encased in concrete, it was found out that the addition theorem can be expressed as follow : [numerical formula]…(1) P=P_c+P_s…(2) in which, P : total compressive load applied to the column P_c : strength of concrete as an integrated unit of column within elastic limit against the compressive loading to which it is subjected P_s : strength of structural steel as an integrated unit of column within elastic limit against the compressive loading towhich it is subjected σ_s=P/A_s A_s : sectional area of structural steel n : ratio of Young's modulus E_s/E_c A_1 : sectional area of concrete in perimeter A_2 : sectional area of concrete in core α_1 : coefficient of stress transmission from structural steel to concrete in core portion α_2 : coefficient of structural steel to concrete in perimeter Moreover, we found from the results of these that α_1 equals to 0.73 and α_2 equals to 0.32 and that the above equation will be not applicable, if it exceds the limits of loadings prescribed in the diagram and when concrete in perimeter yields. At the same time it was found out that there isn't much difference in values α_1 and α_2 when compared between steel column with ribs and without, but the former surpasses the latter in scope within which the above addition theorem can be applicable as shown on the diagram.