Design for durability - A practical approach

Today's building practice has led to a lot of premature failure and lack of durability, which can cause serious safety, serviceability and functional problems. Traditionally design for durability has been performed in an empirical, often unstructured manner based upon implicit durability requirements. A new approach, which ensures that materials and components are suitable and will perform satisfactorily during the intended life, is necessary. Service life estimations are complex and information intensive. In spite of scientific imperfections and lack of information on right format, there is a need for the practical engineer to start using the accessible knowledge. The suggested framework for service life based design, construction and management of building assemblies will ensure that performance requirements are fulfilled during the design life, allows optimisation of the whole life cost of buildings and permits life cycle assessments. The service life influence in different phases, from client's brief till demolition or major refurbishment, can be assessed iri five consecutive stages; conceptual design, modelling and prediction, engineering stage, construction and in service period. The target design life must be determined in an early design stage and will serve as a basis for materials selection, detailed design, execution procedures and maintenance strategy. After predesign the gradual deterioration induced by the interaction between alternative materials and the actual surrounding environment can be estimated. Different approaches can be used for predicting the future behaviour. Models must be based upon a clear phenomenological understanding of the degradation process. In the engineering stage materials selection, detailed design and a quantitative description of products and procedures are executed. In the construction period key factors for durability will be quality assurance of solutions and execution procedures including environmental control. The degradation process and thereby the obtainable service life in terms of performance can in the service period be controlled through adequate operation-. inspection-, maintenance- and repair activities.