Abstract
Reinforced concrete jacketing and steel plate jacketing are widely used to increase the flexural strength of existing reinforced concrete bridge piers. Efforts are being made, therefore, to develop a more efficient and economical seismic retrofit method using a thinner jacketing material. This study proposes an economical seismic retrofit method for increasing the flexural strength of an existing reinforced concrete pier by placing small-diameter steel bars around the pier for flexural and shear reinforcement and jacketing the pier with a thin and light layer of sprayed mortar. In the proposed method, small-diameter deformed prestressing steel bars or high-strength steel reinforcing bars (USD685) are used for axial reinforcement. To ensure ease of installation and minimize effects on footing structure, the embedment end of each axial reinforcement bar is pressed into a flatter and wider shape so that the embedment length of the steel bar in the footing can be made shorter.
Reversed cyclic loading tests on a 1/4-scale specimen mimicking an existing reinforced concrete railway bridge pier showed that the proposed method is a useful means of increasing the flexural strength of an existing reinforced concrete pier and that the load-carrying capacity and deformability of piers retrofitted by the proposed method can be evaluated by using conventional evaluation formulas.
