Presented By: Ali Shokrgozar, Idaho State University

Description: Recently, the Idaho Transportation Department (ITD) proposed a new seismically resilient precast pier system for use in Accelerated Bridge Construction (ABC). The new pier system incorporates the use of steel pipes at the column-to-footing and column-to-cap beam connections. Similar to the connections with grouted ducts and grouted reinforcing bar couplers, the connection is intended to emulate the traditional cast-in-place behavior by forcing the formation of plastic hinges in the pier during an earthquake. The benefits of this new method are: (a) elimination of precise alignment of the pier reinforcing steel bars (rebars) with those of the footing, and (b) avoiding damage to the rebars protruding from the precast pier during transportation and handling. To validate the concept, large-scale experimental testing is carried out on piers at Idaho State University (ISU). The specimens include cast-in-place and precast piers that are tested under quasi-static cyclic loading with increasing drifts. This paper will focus on the development of analytical models for the piers using the Open System for Earthquake Engineering Simulation (OpenSees) software. The cast-in-place pier is modeled with OpenSees’ “Conceret01” and “Concrete04” for unconfined and confined concrete, respectively. “Steel02” material is used for the rebar steel. Bond-slip “ZeroLength” elements are used at the interface of column-to-footing connection to provide better results. Low-cycle fatigue data is incorporated in both the cast-in-place and precast models. The steel pipe in the ITD’s proposed precast connection is modeled as circular “patch” sections with the steel pipe properties. Results show good agreement between the analytical and experimental data. The analytical modeling in this paper is aimed to provide a practical tool for bridge engineers when considering new connection details. In addition to the finite element modeling of the laboratory specimens’ behavior, a bridge in Idaho is modeled.

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