Experimental Studies of Reinforced Concrete Bridge Columns under Axial Load Plus Biaxial Bending

The pseudodynamic testing of two reinforced concrete bridge columns with a reduced scale of 2/5 was performed to obtain their seismic responses to near-fault ground motions. An identical column was also cyclically tested under constant axial load plus biaxial bending to obtain the basic properties of these bridge columns. Biaxial hysteretic loops from both tests show significant stiffness and strength degradations and pinching effect. This attested to the difficulty in developing a mathematical model to realistically capture the load-displacement relation for a reinforced concrete column. The distinct characteristics of round corners and negative stiffness were found in biaxial hysteretic loops obtained from pseudodynamic tests. The scatter plots of pseudodynamic test results also show that the orientations of the resultant flexural moments do not bias in any direction. Thus, this aspect might be considered in the seismic design of a column. Since pseudodynamic results are believed to be more accurate than numerical solutions they can be treated as reference solutions in developing a finite element model. Meanwhile, the hysteretic response obtained from cyclic loading test may be used to match a mathematical model to mimic the very complicated load-displacement relation for analysis. The biaxial hysteretic loops show during unloading more stiffness degradation and pinching than the uniaxial hysteretic loops for both cyclic loading and pseudodynamic tests. This behavior indicates that damage caused in one direction weakens the seismic resistance in the other direction.


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  • Accession Number: 01150783
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Feb 1 2010 12:12AM