Future Directions for Reinforced Concrete Wall Buildings in Eurocode 8

The current Eurocode 8 belongs to one of the most advanced international seismic design codes. This leading edge should be maintained in future revisions of the code while the code should become as user friendly as possible. This article makes several proposals in which way the reinforced concrete wall sections in future versions of the Eurocode can be extended in its scope but simplified in its application. The topics raised concern: (i) Capacity design rules including shear amplification factors, (ii) the reduction of the number of ductility classes, (iii) the out-of-plane failure of reinforced concrete walls, (iv) engineering demand parameters for displacement-based approaches, (v) displacement-capacity estimates for new and existing reinforced concrete members, (vi) the design of mixed structural system, (vii) the design of new structural solutions with reinforced concrete members such as rocking walls. Introduction The current Eurocode 8 (EC8) was largely driven by considerations on reinforced concrete (RC) construction (Fardis, 2013). This is reflected in the number of pages dedicated to the guidelines for RC buildings in EC8-Part 1 (CEN, 2004) as well as in EC8-Part 3 (CEN, 2005), which are significantly larger than for any other structural type. From all structural types, the RC guidelines of EC8-Part 1 and 3 are therefore probably the most complete and contain many approaches that are internationally leading (Booth and Lubkowski, 2012). Future directions should focus on keeping this cutting edge approach. At the same time the code should become as user friendly as possible (Booth and Lubkowski, 2012). It is the author’s opinion that this is best achieved by finding a good balance between simplicity and accuracy and by making underlying engineering models transparent. It is the objective of this paper to raise first thoughts on the future direction of design provisions for RC wall buildings. The following points outline some aspects that could be considered in future revisions of the code. The list also contains some points raised in the discussions following the special session “Future directions of EC8” organised by E. Booth at the Second European Conference on Earthquake Engineering and Seismology in Istanbul in August 2014. The list is certainly not complete and further input is sought from the reader. Capacity design principles Capacity design principles are one of the corner stones of EC8 and one of the most successful concepts in improving the robustness and collapse prevention of structures (Park and Paulay, 1976). Guidelines to incorporate these principles have been well developed for cantilever walls with rectangular or barbelled sections. In the future, capacity design guidelines need to be extended to cover a larger range of wall systems and sections. This concerns both the computation of the shear demand as well as the shear and flexural capacity. On the demand side, the shear amplification factors should be revisited and new formulae introduced that cover a larger range of shear wall systems. Current shear amplification factors in EC8 were derived for cantilever wall systems and should be extended to other very common structural systems, such as coupled wall systems or systems with frames and walls. Such studies are already underway or even completed (e.g., Sullivan, 1 Assistant professor, Head of the Earthquake Engineering and Structural Dynamics Laboratory, EPFL, Switzerland, [email protected], http://eesd.epfl.ch/