Effects of Near-Fault and Far -Fault Vertical Ground Motions on three span railway bridges

The Study on the Accelerometers of the past earthquake indicates that the vertical acceleration can reach values comparable to (and sometimes even higher than) the horizontal accelerations. This study investigates the effect of vertical component of earthquakes on the railway bridges with box girders cross section.
Results of bridge analyses when vertical motions of earthquake are included in earthquake effects are compared to the case when vertical motions are excluded.
Comparison of the results show that the vertical components of ground motions cause significant amplification in the axial force demand in the columns and moment demands in the box girder at both the midspan and at the face of the joints to column. Another finding from the linear analytical study is the fact that the effect of vertical component is completely uncoupled to the horizontal effects.
With the results obtained, the comparison of the results with SDC-2006 suggestions shows that a unit multiplier of the dead load effect for compensation of vertical effect of earthquake. Finally, for considering the effect of an earthquake's vertical component, Dead Load Multipliers have been suggested; they are used in designing bridges.