Obtaining optimal performance with reinforcement-free concrete highway bridge decks

Abstract

This article describes an application of nonlinear finite element modeling (FEM) and analysis in the selection of design details to provide desirable performance in reinforcement-free concrete highway bridge decks. The FEM approach was used to predict the ultimate capacity and failure modes of decks considered as constrained membranes. Lateral constraint of the deck (membrane) provides extra wheel load capacity for reinforcement-free bridge decks on bulb tee wide flanged concrete girders. The wide flange precast prestressed concrete girder sections currently used in bridges result in a shorter effective span for the bridge deck between the wide girder top flanges. The failure mode of concrete decks on these girders with wheel loading is expected to be punching shear. The shear forces from the vehicle wheel loads in the reinforcement-free bridge deck are designed to be carried by compressive membrane action without using reinforcing in the concrete. The compressive membrane action is enhanced by the natural lateral stiffness of the wide girder flanges and by tying adjacent girders together with steel rods placed between the webs. An experimental study of a restrained deck element was performed to identify the failure mode and to use as a basis for verifying the nonlinear properties used in finite element analysis. A parametric study using nonlinear finite element analysis was performed to investigate the factors affecting the ultimate capacity and the failure modes of reinforcement-free bridge decks on wide flange precast girders and to provide a basis for selecting desirable design details.