عنوان مقاله [English]
Skewed bridges have shown vulnerable during the past earthquakes. Observations and numerical studies show that the coupling of the natural vibration modes and rotation of deck may result in considerable seismic demand on deck, abutments and piers. This end up to damage of piers, abutments or deck collapse. Identifying the effective parameters on seismic performance of the bridge enables the designer to find a proper understanding of various aspects of geometry and structural properties in a skewed bridge and may result in selecting appropriate parameters and faster convergence to an acceptable design result. In this research a parametric study was performed over several geometric and mechanical properties of skewed bridged. The objective was to find out the effective parameters on seismic response of such structures. For this purpose a simplified numerical model of skewed bridges was employed. The model was already developed and verified. The model was developed in MATLAB software. The response of the model was calculated for a variety of geometric and mechanical parameters. Evaluations were performed on the results accordingly. Results from numerical calculations revealed that the ratio of transverse stiffness to longitudinal stiffness of the columns, the ratio of length of the deck to its width, the ratio of torsional stiffness of each column to the multiplication of longitudinal stiffness of the bridge to squared width of the bridge deck, the ratio of columns’ eccentricity from the center of the mass to the width of the deck and the skew angle are effective parameters on domination of rotation mode. For further numerical calculations a finite element model of the Foothill Boulevard Skewed Bridge was created and verified in OpenSEES software. A time history analysis was conducted using a pair of a record from PEER ground motion database. Seismic demand on the model was calculated for different skew angles.