High performance material in earthquake engineering

• Head of project: Prof. Dr. A. Dazio
• Assistant: M. Trüb
• Partner: -

Saving lives has always been the key objective of earthquake engineering. However, in recent years, recognizing the steadily growing impact of economic losses on society, strong efforts within the earthquake engineering community have been directed toward the development of high-performance structural and non-structural systems, i.e. systems that are for the same seismic action less prone to damage. In recent years many so-called high performance materials have been developed by material scientists. One of these materials is the Hybrid Fibre Concrete (HFC) developed by the Institute of Building Materials (IFB) of ETH in collaboration with TU Delft. HFC is primarily characterized by a high strength mortar matrix that is reinforced with steel fibres of different lengths. Its main macro-mechanical features are a high tensile strength and a significant strain ductility (with strain hardening). In particular the second characteristic makes HFC attractive for seismic applications.

The research project aims at developing a new high-performance structural system incorporation HFC. The project consists of two major parts, namely an experimental and a numerical one. During the experimental part three medium-scale HFC structural walls were tested under static-cyclic load reversals. The basic idea was to develop a structural wall that would require neither shear nor confinement reinforcement – ensuring therefore an easier constructability compared to conventional RC structures – and which would exhibit a superior seismic behaviour. The tests confirmed the expectations to the fullest. The HFC walls were able to undergo large inelastic cycles without any spalling of cover concrete, and without any consequential buckling of the longitudinal reinforcement or shear failure. The goal of the second part of this research project, which is currently underway, is the development of a numerical, cyclic material model for the simulation of the structural-scale (macro-scale) response of HFC elements. The material model is designed for plane-stress quadrilateral finite elements and uses a combination of the smeared-crack approach and the eXtended Finite Element Method (X-FEM). The latter assures correct strain localisation and allows mesh-independent crack propagation.