inadequate shear capacity which prevented the bridge from utilizing the ductility

available for a flexure failure mode.

 Hasan et al. (2002) used push-over analysis based on the nonlinear relationship of

the M-D curves for the analysis of two steel frame multistory buildings and were able to

determined overall ductility demands and identify the existence of 'soft' stories in the

buildings. They were also able to assess the adequacy of the earthquake-resistance

capacity of the buildings.

 Halabian et al. (2002) used push-over analysis to analyze free standing reinforced

concrete TV towers. They used the M-0 relationships to account concrete cracking and

reinforcement yielding. Their analysis compared well to the time history analyses from

three earthquakes.

 Saatcioglou and Razvi (2002) conducted push over analyses on confined concrete

columns and the results were a good match with the available experimental data from

reinforced concrete columns.

 Plastic Hinge Length

 Determination of the plastic hinge length is a complicated matter and no universal

equation exists. Researchers have introduced empirical equations that can be used to

estimate the plastic hinge length (1p) that for the most part are related to the effective

depth and the distance of the critical section from the point of contra-flexure (Baker and

Amarakone 1964; Corley 1966; Sawyer 1964; Baker 1956;). The experimental research

by the above researchers was conducted on reinforced concrete beams and frames.

Priestly and Park (1987) tested concrete bridge columns under seismic loading and

proposed an equation for estimating plastic hinge length. The equation estimates the

plastic hinge length as a function of the distance of the critical section from the point of