In the European funded research project SBRI a holistic approach is applied to steel-composite brdges by combining ananlysis of Lifecycle Assessment (LCA), Lifecycle Cost (LDD) and Lifecycle Performance (LCP). Under the perspective of sustainability an entire lifespan, from the construction to the demolition of a bridge, is regarded. As German and Portuguese bridge authorities are involved a valuable collection of data in view of existing bridges has been obtained. With the bridge mangement system BMS and SIBBBauwerke a lifecycle scenario was described including maintenance strategies. By postponing and pre-scheduling of measurements optimization towards cost-effectiveness and low envrionmental impact can be achieved.
Assumptions were made for the lifecycle scenario and maintenance actions. These influence not only the lifecycle assessment but also lifecycle and user costs. Optimized crack detection during inspections results in minimization of maintenance needed. The application of post-weld treatment may increase the fatigue resistance of critical details remarkably. The way of construction and materials used are an essential element to act on performances during the different phases of the lifecycle of bridges. Durability can be increased, the frequency of maintenance and the quantities of construction materials reduced. High performance materials, such as high strength steels, can reduce the weight of the structure and optimize the quantities used. In terms of maintenance, the use of specific materials like weathering steels can reduce the vulnerability of the structure to external environmental aggressions. Therewith lower lifecycle costs as well as less environmental impacts are achieved as no renewals of the painting are needed.
The new sustainable design process is evaluated on steel-composite bridges with a complete design of realistic case studies. Following the experience in the different European countries of the project partners, typical road bridges and traffic situations are selected. The functionality and therewith the span length of the bridges is the criteria by which the bridges are divided into three main types. A differentiation between small motorway bridges, crossings of motorways and big motorway bridges is made.
To the case studies the holistic approach of combining LCA, LCC and LCP is applied and optimized. Over the entire lifespan of the bridges none of the factors can be neglected but an optimization of the overall analyses must be found. A most specific description of the lifecycle is therefore a basis for the analyses. In the case studies realistic bridge situations are analysed.
Bridges are “living” structures, however changes during service are difficult and costly in terms of economic and environmental impacts. In a changing environment, these bridge structures must therefore have capacity or reserve of evolutions otherwise they will not satisfy the contemporary needs of users and society over their whole lifespan.