Retrofit Based on Metallic Haunch Solutions

Principal Researcher: Stefano Pampanin
Staff involved: Constantin Christopoulos
Students involved: Tsiu TeChen, Umut Akguzel , Giovacchino Genesio

A viable alternative low-invasive retrofit solution for existing under-designed r.c. frame systems has been recently proposed by Pampanin and Christopoulos (2003) as an extension of new design or retrofit solutions developed for steel moment resisting frames following the significant number of weld fractures observed after the Northridge earthquake (Gross et al., 1999, Christopoulos and Filiatrault, 2000).

Referring to the peculiar brittle mechanisms observed in r.c. beam-column joints, (particularly in exterior Tee or corner joints), the proposed retrofit solution, based on a haunch system aims to protect the panel zone region from excessive shear stress demand, by re-directing the stress-flow around the joint region and enforcing a relocation of a plastic hinge in the beam.

Local tests on fastening techniques under tensile-shear has been carried out at UoC by an internship students Romain Laffont working with Stefano in cooperation with Prof. Eligehausen (Uni of Stuttgart), who has been a regular visitor of UoC in the last three years. Stefano visited Stuttgart last June to further discuss collaboration.

Umut Akguzel (PhD) will continue the development with further tests on b-c joint subassemblies (with and without slab) as well as with a major test on a one or two storey frame with masonry infills. The haunch solution will be inserted in the corner of a frame, with minor disruption of the infills and simple solution and modification in order to allow the strut mechanism to develop.

More information is available at:

Pampanin, S., Christopoulos, C., Chen, T-H (2006) Development and validation of a metallic haunch seismic retrofit solution for existing under-designed RC frame buildings. Earthquake Engineering and Structural Dynamics, 35(14), p 1739-1766. pdf

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