Live Experimental Test
Tuesday, November 17, 2009, 11:00 AM (PST)
Precast Bridge Columns with Energy Dissipating Joints
SE-2 (1/3-Scale Precast Segmental ECC Column)
Previous Experiments - SC-2 - SF-2
PI
M. Saiid Saiidi, Professor, Civil and Environmental Engineering
David Sanders, Professor, Civil and Environmental Engineering
Graduate Research Assistant:
Sarira Motaref, Ph.D. Student
Sponsored by
California Department of Transportation (CalTrans)CalTrans Research Program Manager:
Dr. Li-Hong Sheng
ABSTRACT
Conventional bridge construction involves a time consuming process associated with traffic delays and risk to public safety. In contrast, prefabricated bridge systems can expedite construction, thus minimizing traffic delays and construction site safety risk. Existing details for precast segmental columns offer minimal energy dissipation as a result of the discontinuity of longitudinal reinforcement; therefore, precast members are not used in high seismic zones.
A series of innovative precast concrete segmental columns are being developed and studied at the University of Nevada, Reno through a research project funded by the California Department of Transportation. The purpose of the study is to develop precast columns that are able to dissipate energy under cyclic loading. The first phase of this project involved analytical and experimental study of a segmental concrete column incorporating an elastomeric bearing pad in the plastic hinge. The second phase of the project includes designing and testing three different segmental concrete columns with different low-damage plastic hinges. In one column a conventional reinforced concrete detail is used and it is called SC-2 (Segmental with Concrete). The other two columns incorporate ECC (Engineered Cementitious Composite) referred to as SE-2 (Segmental with ECC) and FRP wrap referred to as SF-2 (Segmental with FRP) at the lower two segments, respectively.
SE-2 is a one-third scale precast segmental column with longitudinal steel dowels connecting the base segment to the footing. The base segment and second segment are made from ECC. ECC is a fiber-reinforced cement-based composite engineered for high tensile ductility, compressive, and tensile strength. It is expected to observe more ductile behavior and fine cracks instead of crushing at interface of base and second segments. Unbonded post tensioning is used to connect the segments and to minimize the residual displacements. Energy dissipation will take place mostly through the yielding of the longitudinal bars at base segment. The column will be subjected to the Sylmar earthquake (Northridge 1994) record with increasing amplitudes until failure.
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