Experimental Research Of Ultimate Bearing Capacity Of Frame Column Section With Two-way Placed Ducts For Tendons Or Strands Under Axes-Pressure

The two-way placed ducts for tendons or strands will weaken greatly the bearing capacity of the PPC frame column. In this case, the two questions have been proposed. Will the section weakened put an adverse influence on the bearing capacity of the frame column? Will the joint area with dense hooped reinforcement enhance the bearing capacity of the frame column? This paper illustrates the experiment on the contrast of the ultimate bearing capacity under the axes-pressure of both four frame columns with two-way placed ducts for tendons or strands (two filled with grout and the other without grout, the two frame columns' hooped reinforcement isφ6.5@100 and the other isφ6.5@75) and one(φ6.5@100) without any duct. The result shows that it is not serious that the influence of those ducts is put on the ultimate bearing capacity of the weakened section of the frame column, when the total section area of the ducts is not beyond 25 percent of the cross-sectional area of the frame column under axes-pressure. It has little effect on the enhancement of ultimate bearing capacity of frame column that the ratio of the hooped reinforcement in the joint area is increased again after it is up to a certain degree.