DEVELOPMENT OF FLEXURAL LOAD CARRYING CAPACITY DUE TO HEAVY CONFINEMENT AND USING HIGH-STRENGTH LONGITUDINAL REINFORCEMENT OF RC COLUMN Heavily confined column under flexure

摘要

The previous reports by the authors have already dealt with the practical stress strain curve, the existence of the threshold steel ratio of longitudinal reinforcements and the quantitative evaluation method of the compressive toughness of the confined RC column. Furthermore, the phenomenal and analytical facts have been clarified that the heavy confinement effect becomes remarkable below the pitch width 40mm of the tie bars. This paper deals with the fundamental analysis of the flexural behavior including the failure mechanism and obtaining the fundamental guideline on the design of RC columns. The main conclusions are as follows. (l)The heavy confinement makes both crack width and crack spacing decrease. (2)There are two categories of "high-densely heavy confinement" and "ordinarily heavy confinement" in the heavy confinement. (3)In the same amount of longitudinal reinforcements, the use of slender bars makes the flexural load carrying capacity decrease. (4)The toughness increases linearly with increase of the flexural loading capacity. (5)The nut anchorage of the primary reinforcement of the column under flexure is connected with its high-performance.