Development of a Simplified Design Method and Reinforcement Detail for the Acute Corner of Skewed Bridge Decks
Funded by: Connecticut Department of Transportation (ConnDOT)
Date: August 2016 – August 2017
In modern transportation projects, skewed bridges are becoming increasingly more common and their degree of skew perceptibly more severe due to more and more restrictive site constraints, especially in urban infrastructure projects. Despite the advantages of skewed bridges, the structural design and construction of the acute corners of skewed concrete slabs present several challenges due to the congested reinforcement details. This may lead to several problems with placing and compacting concrete. At the acute corners of highly skewed bridge decks, the bars perpendicular to the longitudinal axis of the bridge are generally too short to be developed, making them structurally ineffective. In addition, the placement of these bars significantly increases the complexity of construction. Often, as the skew angle increases, large portions of the deck can go unreinforced subjecting them to service issues such as spalling and chipping. The presence of the end diaphragm and an integrated concrete parapet may also have a significant impact on the flexural demand of the deck. In addition, the two-way action of the slab may significantly reduce the flexural demand in acute corners. Hence, an optimal design needs to be developed to account for all these effects to simplify the construction and reduce the costs. This study will use detailed finite element simulation to accurately determine the behavior of skewed slabs. A comprehensive parametric study will be performed to understand the effect(s) of the following parameters on flexural moments and concrete stresses at the acute corner of bridge decks: (1) skew angle, (2) overhang length, (3) girder type, and 4) bridge width and length, (5) end diaphragm, and (6) the presence of an integrated barrier. Concerns about the cost-effectiveness and adequacy of the current reinforcement detail used for acute corners of skewed decks will be addressed in this study. This research will enable the development of an optimized design method and reinforcement detail to reduce the cost and time of construction, while also increasing the safety of the design. The longevity of the bridge deck will also be improved by preventing cracking of concrete deck that is common in skewed bridges.