Effects of column stiffness irregularity on the seismic response of bridges in the longitudinal direction

Abstract

The longitudinal seismic responses of 4-span continuous bridges designed based on the 2006 Canadian Highway Bridge Design Code were studied using elastic response spectrum and inelastic time-history analyses. Several boundary conditions including unrestrained horizontal movements at the abutments and different abutment stiffnesses were considered in the nonlinear analyses. The seismic response of more than 2600 bridges were studied to determine the effects of different design and modelling parameters including the effects of different column heights, column diameters, and superstructure mass as well as different abutment stiffnesses. The bridges were designed using two different force modification factors of 3 and 5. The effects of column stiffness ratios on the elastic and inelastic analysis results, maximum ductility demands, concentration of ductility demands, and demand to capacity ratios were investigated. The results indicate that the seismic response and maximum ductility demands in the longitudinal direction are influenced by important parameters such as the total stiffness of the substructure, the column stiffness ratio, and the aspect ratio of the columns.

Investigating the Use of Natural and Artificial Records for Prediction of Seismic Response of Regular and Irregular RC Bridges Considering Displacement Directions

“…Therefore, these modelling assumptions were adopted for the seismic analysis and evaluation of the bridges in this research. More details concerning the modelling of the bridges and the verification of computer models are available in [1,12,[22][23][24]. bridges in this research.…”

“…bridges in this research. More details concerning the modelling of the bridges and the verification of computer models are available in [1,12,[22][23][24]. The modal properties of the bridges including the fundamental transverse mode, TT, second transverse mode, TT2, fundamental longitudinal period, TL, geometric mean period, TG, (defined as TG = (TL•TT) 0.5 ) and the effective modal mass ratios are presented in Table 1.…”

“…The predictions from elastic analysis underestimated the seismic demands for the case of the irregular bridge. These problems with irregular bridges are studied in more detail by Tehrani and Mitchell [1,22].…”

Effects of Different Record Selection Methods on the Transverse Seismic Response of a Bridge in South Western British Columbia

“…The stiffness and strength of the abutments, soil and piles were computed based on the recommendations by Caltrans [2004]. The gaps between the abutment and bridge deck at the ends were also considered as 50 mm in the abutment model (see Tehrani and Mitchell, 2013 for more details). As shown in Fig.…”

Influence of Abutment Stiffness and Strength on the Seismic Response of Horizontally Curved RC Bridges in Comparison with Equivalent Straight Bridges at Different Seismic Intensity Levels

“…Curved bridges with subtended angles greater than certain limits are considered irregular bridges in bridge design codes [3,4]. It has been shown in the past that irregular bridges are more vulnerable to seismic excitations compared to regular bridges [5][6][7][8][9][10][11]. Experience with past earthquakes proved that this class of bridges is more vulnerable to seismic excitations than that of bridges with straight and skewed typologies.…”