Effects of column and superstructure stiffness on the seismic response of bridges in the transverse direction

Abstract

The transverse seismic responses of continuous 4-span bridges designed based on the 2006 Canadian Highway Bridge Design Code were studied using inelastic time history analyses. A total of 648 bridge configurations were considered in which the column heights, column diameters, superstructure stiffness and mass as well as abutment restraint conditions were studied. The maximum ductility demands obtained using elastic and inelastic analyses were compared to study the influence of the degree of irregularity. The effects of column stiffness ratios and superstructure to substructure stiffness ratios on the maximum ductility demands and concentration of ductility demands were investigated. A number of different regularity indices were compared to determine the suitability of these different indices in predicting the influence of irregularity. This study demonstrates the conservative nature of the 2006 Canadian Highway Bridge Design Code and provides some guidance on factors for determining the degree of irregularity and suitable regularity indices when carrying out nonlinear dynamic analyses of bridges.

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.…”

“…It is noted that to predict the displacement ductility demands, µ, the displacement demands, ∆ u are divided by the yield displacements, ∆ y as defined by the equations provided by Priestley et al [7] (i.e., µ = ∆ u /∆ y ). Further details regarding the predictions of ductility demands is available by Tehrani and Mitchell [1]. To estimate the maximum radial displacement of the columns using the analysis results in the principal directions of the bridges, typically 100% of the absolute displacement in each principal direction is combined with 30% of the absolute displacement in the perpendicular direction (referred to as the 30% combination rule used in codes).…”

“…However, limited research is available to investigate the influence of using different types of synthetic ground motion records on the seismic response predictions of structures, particularly for bridges. Some researchers have studied the use of synthetic records for the seismic evaluation of structures (e.g., [1][2][3][4]), while other studies suggest that more research is needed on the use of artificially generated records for the purpose of seismic design and performance assessment of structures due to different results observed from such ground motion records (e.g., [5,6]). This paper illustrates the use of artificial and natural ground motion records for the seismic evaluation of continuous multi-span reinforced concrete (RC) bridges using 2D and 3D non-linear dynamic analyses.…”

New Extended Quantitative Local and Global Regularity Index for Single‐ and Multiframe RC Bridges Based on Modal Vector Correlation

“…ey concluded that when the deck is stiff enough to control pier displacements, and the distribution of pier's stiffness is symmetric, the proposed criterion offers reasonable accuracy. Several studies served the relative stiffness of deck to piers as an indicator of bridge irregularity [9,10]. Akbari and Maalek carried out an exhaustive comparison between different regularity indices [11].…”