Analysis and Design of Bridge Bent Columns

The behavior of bridge bents under spatial loads was investigated to evaluate the suitability of the current office procedure of the Texas State Department of Highways and Public Transportation (TSDHP'I) for analyzing and designing slender concrete bridge bent columns. Two computer codes were developed for this purpose. The linear method of analysis uses the conventional direct stiffness method of solution and considers linear material behavior. The AASHTO moment magnifier method was used to approximate second order effects. The design forces from the linear analysis were compared with those from the TSDHPT approximate procedure. The effect of variation in live load positions over the bridge deck was examined. The nonlinear method of analysis, developed in this study, uses a fiber model and an updated Lagrange finite element fonnulation to predict the space behavior of multistory concrete bents. The analytical results for typical bents were compared with those from the TSDHPT approximate method and the AASHTO moment magnification procedure. The sensitivity of the results to bent column slenderness and foundation flexibilities were examined in tenns of predicted bent behavior.