Experimental investigation on static and cyclic behaviour of flanged unions for precast reinforced concrete columns

Abstract

Dry connections are widely used in precast structures for their reduced dimensions and faster installation than wet cast-in situ joints. Above all, column-to-footing and column-to-column dry joints represent a very effective alternative to conventional monolithic solutions for columns higher than three storeys, whose transportation and installation turn out to be too much complicated or unfeasible. A wide and safe use of dry joints in precast columns asks for an in-depth analysis of their behaviour, as both their density and technology affect the overall performance of precast structures, especially under seismic loading. The paper shows results of an experimental campaign performed on full-scale specimens to investigate the behaviour of dry connections for precast columns, under both static and cyclic loading. Tests were performed on two types of joints: in the first type the flexural continuity is achieved by welding column’s longitudinal bars to its steel base plate, while in the second type column’s longitudinal bars are overlapped with sufficient length to rebar dowels welded to the steel column base plate. Experimental results show a good performance of investigated joints, in terms of both overstrength and stiffness. Moreover, the ductility and energy dissipation properties of the column’s region adjacent to the joint were evaluated.

Keywords:

• precast concrete
• dry connections
• column-to-footing joints
• experimental tests
• seismic behaviour

Acknowledgements

This research is part of a larger experimental campaign, involving several Italian laboratories and universities such as Milan, Bergamo, Pisa and Naples. The study was funded by the National Manufacture of Cement Industries (Assobeton) and coordinated by Prof. Giandomenico Toniolo (Polytechnic University of Milan), to investigate the behaviour of dry connections between concrete precast elements. The authors gratefully acknowledge Professors Franco Angotti and Andrea Vignoli (DICEA) for critical discussions and suggestions; Eng. Claudio Wang for his help in experimental tests and data analysis; Eng. Cesare Falsini (Baraclit S.p.A.) for providing specimens; Mr. Saverio Giordano, Mr. Enzo Barlacchi and Mr. Franco Bruni (Laboratory of Structures and Materials, DICEA) for execution of tests.