The Influence Of Strengthening Measure On Bearing Capacity Of RC Columns With Initial Load

Almost all the reinforcement in concrete structure are implemented on condition that the structure has alreadly enduced some initial load,whereas current researches more attention to the reinforcement without initial load.To fit the practical project better,it is necessary to study the effects of different reinforcement approaches under initial load.This paper is based on the strengthening experiment of 14 reinforced concrete columns,among which there are 6 columns strengthened with 500kN initial load,6 strengthened with no initial load and two prototype columns.And the strengthened columns are reinforced with CFRP sheets or angle steel and a combination of both respectively subjected to axial compression and 80mm eccentric compression.The performing characteristics and bearing capacity are studied to present the effect of different approaches and compared with the results of strengthened columns without initial load.In the last of this paper,the check and comparison on the bearing capacity of strengthened columns are given,and some suggestions are proposed to improve the current approach of reinforcement design.The test results indicates that combination strengthening has the best effects and the other two approaches have closely effects when the strengthened columns are subjected to 500kN initial axial compression,and each column's bearing capacity reduces to 90 percents of corresponding columns strengthened without initial load.And the test results also indicates that both strengthening with angle steel and with the combination have better effect than strengthening with CFRP sheets when the strengthened columns are subjected to 500kN initial 80mm eccentric compression, and each column's bearing capacity reduces to 80 percents of corresponding columns strengthened without initial load.The results of the experiments shows that combination strengthening is a high quality measure,and the strengthing with angle steel can also acquire fine effect in eccentric compression columns,but further researches on the strength model of the restrained concrete in both 2 above measures are still needed to do.