Behavior and analysis of unsymmetrical double barrel precast concrete box culverts with posttensioning bars

This study focused on the structural behavior of double barrel precast concrete (PC) box culverts where the width of each barrel may vary from that of the other. In lieu of using the elastic foundation beam method, current design codes specify use of reaction method to evaluate the internal force distribution between the two culvert segments. On the basis of a parametric study, a modification of reaction method was proposed to consider the effects of foundation stiffness and structural configuration. The proposed method predicted well the structural behavior of the structure on ground. Further, the structural integrity of each PC segment and between the segments is significantly affected by the sectional layout of posttensioning bars because the cross-sectional area of the culvert is large. Significant stress concentration and nonuniform stress distribution also affects waterproofing performance of elastic sealing rubber strips at joint interfaces. To evaluate this, numerical analysis was performed with various sectional layouts of posttensioning bars. The distribution and average value of stresses were significantly affected by the posttensioning bar layout. Results of this study can be used as reference for design methods associated with double barrel PC box culverts where width of each barrel may vary from that of the other.