Junsuk Kang

Analytical study of minimum cover required for thermoplastic pipes used in highway construction

This paper presents an analytical study on the minimum cover required for corrugated high-density polyethylene and polyvinyl chloride pipes used for under-roadway (cross drain) applications in highway construction. As state highway agencies have only recently begun allowing plastic pipes for cross drain applications, there has been little rigorous analytical research into the minimum cover required for safe traffic load applications using thermoplastic pipes. Furthermore, there is considerable variability among the minimum cover requirements specified by state departments of transportation. The objective of this study was therefore to evaluate the minimum cover required for safe use of thermoplastic pipes for cross drain applications under AASHTO live loads. Analyses were carried out using the finite element method based on a 2D plane strain formulation and nonlinear soil models. Both deflection and stress criteria were evaluated. In general, the required minimum cover resulting from this study was found to be in agreement with most currently used criteria when based upon H25 loading oriented transverse to the pipe; however, significantly higher minimum cover requirements result when the loads are oriented parallel to the pipe.

Screening Tool to Assess Adequacy of Bridge Timber Pile Bents during Extreme Scour Events

AbstractTimber substructure bridges supported by three, four, or five piles were commonly used in Alabama in the past for secondary and county highway bridges. Because of the large number of such bridges in the state, the Alabama DOT recently developed a screening tool to assist its engineers in assessing the adequacy of bridge pile bents for extreme flood and scour events. The evaluation procedure employed in the screening tool is presented in this paper through the following sequence: (1) preliminary or general checks; (2) possible kick-out or plunging failure; (3) bent pile buckling failure; (4) transverse pushover failure from combined vertical gravity and lateral floodwater loadings; and (5) bent upstream pile beam-column failure from combined vertical gravity and lateral debris raft loadings. This paper discusses the theoretical background for the equations used to evaluate each failure mode in the timber screening tool, in addition to describing the flow of the screening process.