Design of Slender Reinforced Concrete Bridge Columns Considering the Interaction between Columns

Abstract

Forces on columns caused by second-order effects are routinely over-estimated, which results in a waste of valuable resources and in construction difficulties because of high reinforcement ratios. This paper introduces a simplified method for the design of slender reinforced concrete (RC) bridge columns that reproduces the interaction between columns of the structure and its effects on their second-order behavior. The method considers that the instability of the more slender columns is affected by the horizontal displacement stiffness of the less slender columns, thereby increasing the horizontal forces acting on the less slender elements. Two application examples are presented and the results obtained with the new method are compared with the results obtained by applying the simplified formulations of two major concrete design codes, as well as a nonlinear finite element design of the whole structure. The results show that the codes tend to produce over-conservative designs for slender elements while the new method produces designs that better match the results obtained using the more sophisticated finite element approach, still maintaining a margin of additional safety.