Geotechnical design is a product of local history, engineering practice, availability of construction materials and, of course, the geology of each site. All of these factors vary from region to region, which is why a standard recipe for developing geotechnical codes of practice does not exist. It is probably fair to say that the differences in geotechnical design codes worldwide are much larger than exist between steel or concrete design codes. Steel and concrete are quality controlled materials and the uncertainty in their engineering behaviour is very similar from region to region. Thus, concrete and steel design codes have been able to take advantage of worldwide research efforts in their calibration over the decades.
Modern geotechnical design codes are generally striving towards a similar harmonisation, both with their counterpart structural design codes and between regional geotechnical codes. However, harmonising geotechnical design codes is not an easy task. An excellent example of the challenges faced in harmonisation is presented by Eurocode 7. Although aiming to create common terms of reference, Eurocode 7 still required several design approaches to accommodate the needs of all member states, along with national annexes enabling each member state to define their own set of safety factors. Why was this diversity in design approaches necessary? And what do code developers have in mind when they make their choices in adopting a design approach or set of safety factors? Some answers to these questions will be given in this book.
The impetus for this publication started with an international workshop on Safety Concepts and Calibration of Partial Factors in European and North American Codes of Practice, which was held on November 30 to December 1, 2011 at Delft University of Technology, the Netherlands. The aim of the workshop was to exchange ex perience and transfer knowledge between code developers, practitioners, and researchers on code development, safety concepts and the calibration of partial factors in modern geotechnical codes of practice. The attendees, who were leading authorities from Europe and North America, provided interesting and valuable insights into the development of their own national codes. This workshop led to the idea of collecting contributions from geotechnical code developers worldwide into a single book, providing a resource that can be referred to as a guide in the years to come.
The papers collected in this book are organised into three sections: Code Implementation describes choices relating to safety concepts, target reliabilities, and design approaches; Code Application addresses their application to specific geotechnical problems; and Code Development includes papers discussing directions for future developments.
The editors would like to acknowledge the support of the following committees who have substantially contributed to and supported this publication: the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) Technical Committee for Safety and Serviceability in Geotechnical Design (TC 205), Technical Committee for Engineering Practice of Risk Assessment and Management (TC 304), and the Comité Européen de Normalisation (CEN) Technical Committee for Structural Eurocodes (TC250).