RELAST | Post-installed retrofitting system
For improving the punching shear and shear capacity of reinforced concrete elements
Finding appropriate strengthening solutions for existing reinforced concrete (RC) elements is always a challenge for structural engineers. Additional load capacity may be needed as the change of type of occupancy and more restrictive design standards require higher load levels or different detailing of reinforcement. Growing traffic volume would be a main topic in bridge design. This very often affects the shear and the punching shear and its reinforcement level.
This paper introduces a post-installed retrofitting system consisting of an adhesive and a concrete screw anchor that can be used to improve either the pure shear capacity or the punching shear capacity of a RC beam or slab. This post-installed retrofitting system acts as shear reinforcement that can be installed with relatively minimal disruption as it is only installed at the soffit of the RC element being strengthened. The system was tested for its suitability and the results were approved by the German Construction Authority DIBt with a National Technical Approval. Published parameters are used for the standard methods of detailing shear and punching shear of a RC element according to EN1992-1 and EN1992-2.
Calculations and tests have shown that with the use of this post-installed retrofitting system, the shear strength of existing concrete elements can increase by up to 100% and consequently increase the lifetime of a structure. This paper also discusses the test methods employed, the test results, and sample projects that made use of the said system. Another important finding is the substantial savings in project cost attributed to the installation methodology that comes with the system. Demolition of old structures, and building a new one is no longer the only feasible option.