Retrofit Solutions Wellington

Beam-column Joint with Inadequate Detailling

Principal Researcher: Stefano Pampanin
Staff involved: Athol Carr, Des Bull
Students involved:Eric Hertanto, Chen T-T, Kam Weng Yuen, Umut Akguzel, Patricio Quintana Gallo,

The significant risks associated with substantial damage and global collapse of existing reinforced concrete (r.c.) moment-resisting frame structures designed prior to the introduction of modern seismic design codes in the mid-1970s are well acknowledged. Recent experiences with large earthquakes near populated centers (Sichuan, China 2008 and Izmit-Kocaeli, Turkey 1999) further highlight the urgent need for economical and effective seismic retrofit techniques for these structures.

Left: Damage of Beam-column Joints from L'Aquila 2009 Earthquake (photo credit: Dr Anna Brignola, University of Genoa). Right: Collapsed buildings during Wenchuan 2008 Earthquakes (Photo Credit: adapted from Wu etal, Paper S31-4, 14WCEE,2008)

The vulnerabilities of pre-1970s rc buildings have been identified to be due to the absence of adequate seismic design provisions, capacity design considerations and detailing for ductile behaviour (NZSEE, 2006). Experimental tests of sub assemblages (Aycardi et al., 1994) and rc frames (Calvi et al., 2002) have shown that the excessive damage or failure of beam-column joints, in particular exterior (or corner) joints, can lead to the global collapse of a building. The poor joint behaviour of older construction can be attributed to: the inadequate shear reinforcement in joint region, the poor bond properties of plain round bars reinforcement (commonly used prior to 1970s) and the deficient anchorage details into the joint region (Hakuto et al., 1997).

The research conducted under this project at the Structural Laboratory of Dept Civil Engineering at the University of Canterbury focusses on several additional parameters:

In addition to be used as benchmark specimen to various retrofitting solutions specimen, the experimental data derived from this research work also added to the global knowledge base of rc beam column joint with inadequate detailing - which is inadequate at present stage.

The semi permanent bi-directional and uni-directional beam-column joint testing setup at the Structural Laboratory of Dept Civil Engineering at the University of Canterbury. Special acknowledgement to the FRST Project technician - Mr Mosese Fifita who have contributed much to the experimental research work described in here.

Selected Publications:

Akguzel, U., Pampanin, S., (2009) "Analytical Model for Shear Strengthening of RC Beam-Column Joints Using Composite Materials." Proceedings of the Annual NZSEE 2009 Conference, Christchurch, April 2009. Paper No 53 pdf

Kam, W.Y., Pampanin, S., Bull, D. (2009)"Experimental Validation of Selective Weakening Approach for the Seismic Retrofit of Exterior Beam-Column Joints." Proc. of 2009 NZSEE Conference, Christchurch, New Zealand. April 2009. pdf and ppt

Kam, W.Y., Pampanin, S. (2008) "Selective Weakening Techniques for Retrofit of Existing Reinforced Concrete Structures" Proc. of 14th World Conference on Earthquake Engineering (14WCEE) 2008 , Beijing, China. (Paper ID: 05-03-0074) pdf

Pampanin, S., Akguzel, U., Attanasi, G. (2007) Seismic Upgrading of 3-D Exterior R.C. Beam Column Joints Subjected To Bi-Directional Cyclic Loading Using GFP Composites,. Patras, Greece: 8th International Symposium on Fiber Reinforced Polymer Reinforcement for Concrete Structures, 16-18 Jul 2007. pdf

Hertanto, E. (2005) "Seismic Assessment of Pre-1970s Reinforced Concrete Structure." M.E. Thesis. Department of Civil Engineering, University of Canterbury. pdf

Pampanin, S., 2005 “Seismic Vulnerability Assessment and Retrofit Strategies for Under-designed Reinforced Concrete Buildings”, Proceedings NZSEE National Conference, Wairakei. pdf [coming soon]

For further information, please contact the researchers listed above.