Reduction of differential column shortening by placing additional reinforcement

A method to reduce differential column shortening in reinforced concrete (RC) tall buildings by placing additional reinforcement at the columns is proposed. The axial stiffness of columns with greater shortening than adjacent columns connected through horizontal members should be increased to reduce differential column shortening. The axial stiffness of the columns can be effectively increased by placing additional reinforcement at the columns. Factors that affect the efficiency of reinforcement at reducing column shortening were investigated through single-column analysis, sensitivity analysis of a multi-storey column line and a comparison of three distribution schemes. A step-by-step method for the long-term analysis of RC structures is applied for the exact column shortening for any elapsed time. Based on the results, differential column shortening can be reduced in the design stage by placing additional reinforcement at the columns.