Development of a Ridged Slip-Resistant Connection for Modular Aluminum Bridge Deck Applications

Abstract

Aluminum is a lightweight material that possesses excellent corrosion resistance and has been shown to be an attractive alternative to steel and concrete for the construction and rehabilitation of bridge structures. It is often possible to increase the load-carrying capacity of a bridge with an existing concrete deck by reducing the structure’s self-weight through the installation of an aluminum deck. For new construction, aluminum can allow for the use of accelerated bridge construction (ABC) methods as the lightweight components can be easily transported and installed on site. Aluminum also offers potential for lower life-cycle costs due to its high corrosion resistance, which reduces maintenance requirements and eliminates the need for protective coatings.

One of the latest developments in bridge construction and rehabilitation is the modular aluminum bridge deck system, which consists of a series of pre-fabricated panels that are fastened together to form a continuous deck. Welds and mechanical fasteners can both be used to join the panels together. However, a mechanical fastening system is often advantageous for ease of transportation and installation. Modular aluminum bridge deck systems offer all of the benefits that are associated with the use of aluminum for bridge structures, and their modular design provides opportunities for ABC methods in both new construction and rehabilitation projects. They are currently more commonplace in Europe than in North America, however, which is due, in part, to a lack of commercially available products in the North American market. There is a particular lack of products that implement a mechanical fastening system for the panel-to-panel connections. A need has therefore been identified to develop a novel modular aluminum bridge deck system with mechanical connections for vehicular bridge structures in North America.

The research presented in this thesis focuses on the development of a novel ridged slip-resistant connection for future implementation in a modular aluminum bridge deck system. Ridged slip-resistant connections consist of interlocking faying surfaces, which are clamped together with mechanical fasteners, with the goal of providing improved strength and ductility compared to equivalent slip-resistant connections with flat faying surfaces. In the current study, their performance is validated through experimental testing, finite element modelling, and the development of a simple mechanistic model for predicting their slip-resistance.

An experimental program was carried out to study the performance of ridged and non-ridged slip-resistant connections with carbon steel and stainless steel bolts. Static and cyclic tests were performed on small-scale lap-splice specimens fabricated from 6061-T6 aluminum. The results of the static tests were used to characterize the behaviour of ridged slip-resistant connections and to quantify the performance gains between the ridged and non-ridged specimens. The results of the cyclic tests were used to provide a preliminary assessment of the fatigue performance of ridged slip-resistant connections.

Finite element (FE) modelling was conducted to predict the behaviour of each experimental test specimen. The slip loads predicted by the FE models were compared to the experimental observations and were then used in combination with the experimental observations to validate an equilibrium-based mechanistic model. The mechanistic model was combined with the existing design provisions of CSA S6 Canadian Highway Bridge Design Code (CSA Group, 2014) to develop a design equation for aluminum ridged slip-resistant connections at the service limit state. The stress concentrations predicted by the FE models were used as inputs for a strain-life analysis, which was carried out to predict the fatigue lives of the cyclic experimental test specimens. Further FE modelling was conducted to study a full-scale modular aluminum bridge deck system so that the feasibility of implementing ridged slip-resistant connections between the panels could be verified.