Aaron Yakel

Flexible Pile Head in Jointless Bridges: Design Provisions for H-Piles in Cohesive Soils

AbstractSeveral methods are used to increase the lateral displacement capacity of the piles supporting jointless bridges, the most effective of which are predrilled holes and a flexible pile-cap connection. Depending on soil type and required displacement capacity, these two methods can be combined. This paper discusses a simple study carried out to demonstrate the efficiency of the flexible-head condition, and a finite-element analysis conducted on a prestressed pile. The model was first calibrated with the test results, and then a flexible detail was applied to the model. The results of this part of the study show that a flexible connection can increase the displacement capacity of embedded piles. Finally, nonlinear analyses were conducted using simulation software for compact HP piles. The results of these analyses revealed that strong axis bending results in larger displacement capacity compared to weak axis bending, although the stiffness is smaller in the latter case. Provisions are also developed t...

Delayed development of composite action in steel girder bridges

Development of a bridge system where composite action is developed after the concrete has hardened would reduce the extent of cracking observed in bridge decks while elimination of shear studs would reduce the potential tripping hazard to workers. The objective of this research was to recommend a system which met one or both of these goals. To this end, a number of component level tests along with two prototype beam tests were performed. Details of the testing are described in the paper. Of the alternatives considered, two systems appear to offer the most promise for eventual implementation. The first system utilizes a plastic boot placed over the stud prior to casting of the concrete creating a void around the stud. After the concrete has cured the boot can be punctured or removed and the void filled with an epoxy grout. Upon curing the system will perform as though the studs had been directly cast into the concrete. The second recommended alternative utilizes a single plate welded along the length of th...