Master of Engineering (Hons.)
Department of Civil and Mining Engineering
Qian, Han, Behaviour of precast reinforced concrete beam-column connections under static and repeated loading, Master of Engineering (Hons.) thesis, Department of Civil and Mining Engineering, University of Wollongong, 1994. http://ro.uow.edu.au/theses/2421
Connection design is one of the most important considerations for the successful construction of precast concrete structures. The configuration details of the connection affect the strength, stability, ductility as well as load redistribution of the structure under loading.
Since the 1980's, extensive laboratory testing and research work has been conducted to study the seismic behaviour of beam-column connections in cast-in-place reinforced concrete building frames. However, only a limited number of studies have been conducted on the performance of precast concrete connections, and into a lesser extent on moment resistant precast concrete beam-column connections. This is in spite of the fact that precast concrete connections have been in use all over the world since the 1950's. Reliable connection behaviour can only be verified by testing, although the ACI Manual and the Australian Manual describe nearly 40 beam-column connections fulfilling many functions. Therefore, it is desirable to perform tests on more precast beam-column subassemblies.
This study investigates the performance of two types of moment-resisting connections for joining precast beams and columns, which were recommended by the American Prestressed Concrete Institute (PCI) and Australian Prestressed Concrete Group (APCG) for use in precast reinforced concrete building frames. A total of twelve half-scale model connections, divided into two groups according to the type of loading were designed, manufactured and tested to failure under static and repeated loadings. Each group had two monolithic models for the purpose of comparison and two models of each type of precast connections. The beam and column dimensions, the strength of precast concrete and configuration details were kept constant to afford a direct comparative study of connection behaviour. The only variable used in the study was the steel ratio of tension bar in the connecting beams. Each type of connection in each group had two steel ratios corresponding to the two cases, ρt-ρc=2/3 ρall and ρt- ρc=ρall, respectively to study the effect of the amount of reinforcement in the subassemblies. Note that (ρt-ρc) is the steel ratio difference between the tension and compression bars and ρall is the tension steel ratio allowed by the Australian Standard.
The objective of this study is to develop a moment-resisting precast concrete beamcolumn connection that is economical and can be easily constructed. The connections are evaluated based on their performance in terms of strength, deformation ductility, crack features, failure modes and energy dissipation characteristics as well as their constructibility.
From the comparative study, it is found that both types of precast connections performed satisfactorily in that their bending strength capacity and energy absorbing capacity are, without exception, better than the monolithic ones. In addition, their ductility, in general, is superior to their monolithic counterparts. This indicates that both types of precast connections can be considered as moment-resisting ductile precast concrete beam-column connections and can be safely applied to precast reinforced concrete building frame construction.
Finally, in light of the test results, the relative merits of the two types of precast connections are discussed and recommendations given.