This paper presents findings from the first phase of testing at the University of Canterbury on seismic performance of emulative connections for Accelerated Bridge Construction (ABC) in regions of moderate to high seismicity. Emulative connections between precast concrete elements aim to target similar seismic behaviour as traditional ductile monolithic construction. The emulative solution in this research is called “High Damage Connection” (HDC).
HDCs intend to achieve similar levels of seismic performance and ductility in a precast column as that can be expected of a monolithic one. HDC relies on formation of plastic hinges in the precast column during a design level earthquake to emulate monolithic ductile behaviour.
Two types of HDCs, the grouted duct connection and member socket connection, were investigated in this research. Four half-scale precast segmental columns were constructed. Two columns featured grouted duct connections as the primary connection type. The other two columns used member socket connections. For a better understanding of the connection response under severe lateral loading, both uniaxial and biaxial testing of the columns was carried out.
In this paper, an introduction to each connection type followed by design procedure, detailing considerations and construction methodology are explained in detail. Testing results and observations of seismic performance for each connection are thoroughly presented. The research concludes that High Damage Connections have good potential for ABC in regions of moderate to high seismicity. The connections that were tested achieved good levels of energy dissipation and ductility with similar performance to conventional monolithic connections.
This paper investigates the effects of the nonlinear behaviour of isolation pads on the seismic capacity of bridges to identify the parameters of base isolation systems that can be used to improve seismic performance of bridges. A parametric study was conducted by designing a set of bridges for three different soil types and varying the number of spans, span lengths, and pier heights. The seismic responses (acceleration, displacement and pier seismic forces) were evaluated for two structural models. The first model corresponded to the bridges supported on elastomeric bearings with linear elastic behaviour and the second model simulated a base isolated bridge that accounts for the nonlinear behaviour of the system. The seismic demand was represented with a group of twelve real accelerograms recorded on the subduction zone on the Pacific Coast of Mexico. The nonlinear responses under different damage scenarios for the bridges included in the presented study were estimated. These results allow determining the seismic capacity of the bridges with and without base isolation. Results show clearly the importance of considering the nonlinear behaviour on the seismic performance of bridges and the influence of base isolation on the seismic vulnerability of medium size bridges.
