Report No.: CCEER-06-1
Title: Development of a Seismic Design Method for Reinforced Concrete Two-Way Bridge Column Hinges
Authors: Zhiyuan Cheng, M. "Saiid" Saiidi, and David H. Sanders
Date: February, 2006
Sponsoring Agency: Nevada Department of Transportation (NDOT)
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557
Two-way hinges are commonly used in bridge columns to reduce column moment transfer to foundation. Currently the shear capacity of two-way hinges is determined using the shear friction method. When subjected to lateral forces such as earthquake load, hinges are under a combination of axial load, shear as well as moment. The shear transfer mechanism is different from the assumptions in the standard shear friction theory. However, limited studies are available and no rational code provision for two-way hinge design exists.
The main objective of this study was to investigate the performance of two-way hinges subjected to combine vertical and lateral loads including seismic forces, and to develop a comprehensive and reliable design method for practical application. Five 1/3-scale reinforced concrete bridge column specimens with two-way hinge details were tested under real earthquake motion using shake table. Several major parameters that may affect the hinge and column performance were included in tests, such as the level of axial load, column aspect ratio, column and hinge steel ratio, and the size of hinges. The test data showed that regardless of the variation of different parameters, the shear capacity of two-way hinges is much lower than the shear friction theory estimates. A procedure for two-way hinge design including a rational method to determine the shear capacity of the hinge is proposed in this study. The proposed design method produced a close and conservative estimation of the lateral-load strength of two-way hinges.
Additional analytical studies also included push-over analysis, development of a two-way hinge concrete confinement stress-strain relationship, and development of a two-way hinge plastic hinge length model for two-way hinge rotation and gap closure calculation. The proposed hinge shear force-slippage model improved the deflection calculation of the column with two-way hinge detail.