• Consulting in the field of earthquake protection, especially for masonry buildings.
• Empa develops new methods of retrofitting in cooperation with industrial partners. Empa accompanies the development of new materials and methods from the initial concept to a commercial product.
• Empa performs laboratory and field tests on retrofitted structures to verify safety and serviceability by applying static and dynamic loads.
• Empa consults building owners and engineers about materials and techniques for retrofitting of struc-tures such as bridges and buildings.
• Empa monitors retrofitted civil structures.

Contact: Prof. Dr. Masoud Motavalli, Dr. Christoph Czaderski

TULCOEMPA – Strengthening of a prestressed concrete road bridge with prestressed CFRP strips
In collaboration with the Technical University of Lodz (Poland) a retrofitting concept for a prestressed concrete road bridge is elaborated.

The strengthening will be realized with prestressed CFRP strips anchored with the ‘gradient anchorage’ developed at Empa.

A special anchorage device previously developed in the framework of an industrial R&D project will be applied for the first time on a bridge construction. Two large-scale girders have been built 1:1 at Empa laboratory according to the original elements and will be used for static load testing for demonstrating the higher bearing capacity of the retrofitted structure.
Partner / Financing: www.tulcoempa.com

Contact: Dr Julien Michels, Dr Christoph Czaderski, Prof. Dr. Masoud Motavalli

Strengthening of reinforced concrete members by prestressed, externally bonded reinforcement with gradient anchorage
The aim and motivation for this PhD work was to better understand the bond behaviour of prestressed CFRP strips in the region of the gradient anchorage. Detailed insights in the structural behaviour of CFRP strips that were glued on a concrete surface were found in lap-shear, prestress force release and beam tests. Full-field displacements measurements were performed by using an optical 3D image correlation measurement system. See http://dx.doi.org/10.3929/ethz-a-007569614
Contact: Dr. Christoph Czaderski

Earthquake retrofitting of rectangular reinforced concrete columns using fiber reinforced polymers
Many existing buildings have ground floors where the walls are replaced by columns to open the space for retail shopping or parking. Stair cases may not be adequate or positioned eccentrically. This results in so-called “soft-stories”, one of the most common causes of failure in earthquakes, because the columns are usually not designed for earthquake loading.Deformation capacity and ultimate resistance may be increased easily by confinement, in the case of round reinforced concrete columns. Rectangular columns are commonly encountered in existing build-ings. A conventional confinement technique is not very efficient for rectangular columns.
A system is developed herein to achieve larger plastic deformations and higher load carrying capacity for rectangular reinforced concrete columns.
Also bridges and stone fall protectors with this novel system better resist to effects due to impacts, ex-plosions and earthquakes.
Contact: Dr. Andrin Herwig

Seismic retrofitting of unreinforced masonry using post-tensioning
Many existing buildings worldwide are made of unreinforced masonry with very little resistance to horizontal loading. An efficient way of improving their seismic behaviour is retrofitting by post-tensioning. The additional vertical load increases the horizontal resistance considerably but can also reduce the deformation capacity, which is an important parameter in displacement-based design.
The goal of this project is to find the optimal application of post-tensioning and to develop corresponding design rules.
Contact: Dr. Benedikt Weber, Abdola Sadeghi