Corrosion resistant composite bridges using stainless steel I-sections and shear studs

This project investigates the use of stainless steel I-sections and shear studs in steel-concrete composite bridges. Bridge structures present many challenges to contractors and structural designers owing to harsh environments, large/variable structural loading and limited access to the sites in which they are often located. Construction and maintenance of these structures can be timely and expensive, particularly in environments where salt and water are present. Unfortunately, on some occasions in the past such as the Mianus River Bridge in Connecticut, corrosion of certain elements in bridges has led to structural collapse and loss of life. Steel-concrete composite beams, comprising a steel I-section connected to a concrete slab by shear connectors, are widely used in buildings and bridges since this system optimises the use of each material and enables beams to span long distances unsupported. However, most research to date has focussed on carbon steel in these applications. Stainless steel has been traditionally less popular owing to its higher material cost and limited available design guidance. Researchers have also increasingly turned their attention to this material in recent years, leading to a better understanding of its structural properties and performance. Stainless steel offers many advantages over carbon steel, most notably superior corrosion resistance. This reduces the need for bridge maintenance and so the higher material cost is compensated for by lower life-cycle costs. This improved corrosion resistance also reduces the likelihood of structural failure. The aim of this research project is to conduct a series of laboratory experiments (push-out tests and full member bending tests) on stainless steel-concrete composite specimens using stainless steel I-sections and shear studs in order to assess the performance of stainless steel. The experiments will be conducted in the strong floor in the structural engineering laboratory of the University of Bradford. Comparisons will be drawn between the performance of stainless steel and carbon steel components. Different types of shear stud will also be compared - welded and bolted/demountable. The demountable shear studs offer further potential advantages with regard to ease of construction/dismantling and a potentially better performance under fatigue loading than welded studs. Following the experiments, numerical models will be developed using finite element software in order to extend the results of the research and enable parametric studies. The results will eventually be used to develop guidelines for incorporation into Eurocode 4, promoting the exploitation of stainless steel to provide safer, cost-effective and lower maintenance steel-concrete composite structures.

The proposed research will have a positive impact on academics, members of the construction industry and the general public.

The principal investigator will share the findings with academics in her research field through participation in research seminars within her own institution, research meetings with academics in other institutions and participation in international conferences. The results will also be published in world leading scientific journal papers. The unique set of data from the experiments will be shared with the scientific community to enable further research and/or comparison with other data sets. The findings will not only contribute to knowledge in an established research field, but also carve out a new 'niche' within steel-concrete composite structures. The experience and outputs will significantly enhance the PI's career prospects and establish her as a known expert in her area.

The results will be beneficial to members of the construction industry. Experts from the Steel Construction Institute and Outokumpu have already expressed their interest and willingness to support this project. A steering committee can be set-up to meet bi-annually, at which the project findings can be discussed. At the end of the project, a workshop will be organised for all interested members of the steel-manufacturing and construction industries and each attendee will receive a copy of a technical report on the findings. If successful, the experiments will demonstrate the suitability of stainless steel and demountable shear connectors for the proposed application, providing an efficient solution to bridge design. Design guidelines will be developed in conjunction with one of the project industrial partners, the Steel Construction Institute, which can be later be incorporated into Eurocode 4. A webpage will be set up to report the progress of the project. This page can also host a forum for communication between designers. Software and smartphone applications will be developed to help with design of stainless steel-concrete composite beams, and these will be available from the webpage.

The increase in usage of stainless steel could also rejuvenate the steel manufacturing industry in the UK, generating an increase in employment and trading opportunities. The improved safety and efficiency in bridge design will benefit a wide range of stakeholders, including the general public. The corrosion resistance of stainless steel will reduce the need for maintenance and repair, which can cause inconvenience to bridge users. The improved sustainability of the design will enhance the overall quality of life for members of the public.

The project will provide several opportunities for future research projects with members of the academic community and the construction industry. Although it is envisaged that the primary beneficiaries will be those that work within the civil engineering and construction industries, opportunities for interdisciplinary future research will also be explored.