رفتار لرزه ای پایه های بتنی مورد استفاده در سازه های پل واقعی Investigation and verification on seismic behavior of precast concrete frame piers used in real bridge structures: Experimental and numerical study

1. Introduction Bridge design and construction have experienced innovations and advancements in recent years, which lower overall cost, simplify construction process, and save time [1]. Bridge columns, cap beams, and bridge girders can be prefabricated in factories or near construction sites. These components are then assembled on-site using different types of connections for accelerated construction. However, connections are usually applied to critical structural locations (e.g. column-cap and column-footing joints), where plastic hinges are likely to form under strong earthquakes. Thus, studies on the bridge structures with moment-resisting connections need to be taken special care of in moderate-to-high seismic zones. Five different types of connections were studied and used in real applications [2]. Socket connection, applied to column-footing joints, was recently utilized for highway bridges, and studies showed acceptable seismic performance [3,4]. The second type is pocket connection, and its seismic performance was also reported to be comparable to castin-place (CIP) structures [5]. Prestressing tendon is the third type of connection, which is commonly used in precast segmental bridge columns. Seismic behavior of these precast segmental posttensioned bridge columns was investigated experimentally, and test results showed that the segmental columns exhibit good drift capacity and ductility, and energy dissipation capability can be ensured by using energy dissipation bars [6,7]. The remaining two connection types are grouted corrugated duct connection (GCDC) and bar coupler connection, and these connections are studied in this paper. GCDC was originally developed for column-cap connections [8,9], but study of column-footing connection using GCDC was also conducted with promising results for construction [10], and good ductile performance was observed when compared with CIP systems. The bar coupler connection includes several types of proprietary mechanical bar couplers or splicing devices, one of which is grouted splice sleeve coupler (GSSC). GSSC was also studied for applications in seismic zones, including the utilization of multiple reinforcing bars, high-strength grout, and cast iron sleeve [2,11–13]. The experiments showed that specimens using GSSC and corresponding CIP structure retained equivalent strength capacity, but displacement capacity was found to be lower [14–17]. Further research studies revealed that displacement capacity can be improved by allowing debonding of reinforcing bars outside the GSSC [18]. Comparison of three specimens with various GSSC embedding locations also confirmed results of previous studies [19].