Length Limitations of Prestressed Concrete Girder Integral Abutment Bridges

Open Access
Author:
Baptiste, Keisha Terry
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Jeffrey A Laman, Thesis Advisor
  • Andrew Scanlon, Thesis Advisor
  • Angelica Palomino, Thesis Advisor
Keywords:
  • bridges
  • prestressed concrete
  • integral abutment
  • length limits
Abstract:
The construction of integral or jointless bridges in North America has become increasingly popular because of the many advantages over conventional, jointed bridges. However, conservative limits have been set on the maximum length of integral abutment bridges (IABs) because no analysis or design guidelines for IABs exist. Additionally, the behavior and potential problems associated with IABs at increased lengths are largely unknown. This study developed 3D numerical models in ANSYS that simulate IAB behavior to study the critical bridge response, establish a practical IAB maximum length, and identify potential distress in IABs at extreme lengths. Key components to IAB behavior included in the numerical models are soil-pile interaction, abutment-pile interaction and construction joint detail. The loads on the numerical models were ambient temperature, AASHTO temperature gradient, time-dependant loads, and backfill pressure. A parametric study was performed with an initial bridge length of 1000Œ (305 m) considering the effects of: (1) abutment height; (2) soil stiffness; (3) construction joint flexibility; and (4) pile orientation on IAB response. Results of the parametric study showed weak axis oriented piles developed higher pile stress than strong axis oriented piles and abutment height had the greatest effect on IAB critical response. Taller abutments, moderate construction joint stiffness, low soil stiffness and strong axis pile orientation are best suited for IABs at extreme lengths because these conditions yield comparatively lower pile stress, moment and concrete stress at the abutment-pile connection. Based on analysis results, IABs at extreme lengths develop high stress in the piles, deck, the abutment at the construction joint and the backwall-girder connection, limiting the length of IABs. A practical maximum length of 1500Œ (457 m) was established based on IAB limiting factors. For IAB lengths beyond 1500Œ (457 m), cracking will most likely develop at the backwall-deck connection, the abutment at the construction joint and at the abutment-pile connection. High stress, approaching yield, is also likely to develop in steel H-piles in IABs at extreme lengths.