Analytical study of the coupled motions of decks in skew bridges with the deck–abutment collision

Abstract

It has been observed from failures of highway bridges during major earthquakes that skew bridges are among the most vulnerable to seismic loading. It has been shown that the coupling between the translational motions of the deck and the collision of the deck with the abutments are two major factors influencing the vulnerability of skew bridges. This paper studies the influence of deck–abutment collision (seismic pounding) on the coupled motions of decks of skew bridges during strong earthquakes using an analytical approach. A three-degree-of-freedom model is presented to study key dynamic features of skew bridges. It is assumed that the deck of the model is rigid and the columns remain elastic during the ground motion. Contact planes between the deck and the abutments are idealized by several contact points pairwise arrayed at the end-span expansion joints. The mechanism of energy absorption and dissipation during the contact duration is simulated through the implementation of a nonlinear contact element between the contact points. A parametric study has been carried out by varying different parameters, including the skew angle (β), the size of the gap between the deck and the abutments at the end-span expansion joints (gap), and the normalized stiffness eccentricity along the x-axis ( ex/ r). The results of this study show that the transverse displacements of acute corners of the deck and the rotation of the deck about the mass center noticeably increase with the increases of β and ex/ r, and with the decrease of the gap.

Dynamic characteristics of horizontally curved bridges

“…This assumption underlines this fact that the total mass of the piers is negligible compared to that of the deck (Meng et al. 2001; Amjadian et al., 2016; Amjadian and Agrawal, 2016).

Figure 1.Three-degrees-of-freedom (3DOF) analytical model of a typical horizontally curved bridge; (a) plan, (b) transverse cross-section at the piers, and (c) details on the modeling of the bearings at the abutments, respectively.

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“…The shear stiffnesses of the bearings are usually in the range of 1 MN/m to 2 MN/m such that their ratios to the shear stiffnesses of the columns are as small as 10 -2 or less (Priestley et al., 1996; Naeim and Kelly, 1999). Therefore, it is assumed that the bearings at the abutments act as ideal roller supports, implying that their shear stiffnesses can be disregarded in comparison with those of the columns (Amjadian and Agrawal, 2016; Amjadian et al., 2016).…”

“…The dynamic characteristics of a highway bridge depend very much on its geometry, mass, and stiffness. Therefore, highway bridges with irregular geometry and nonuniform mass and stiffness distribution, such as horizontally curved bridges (Amjadian and Agrawal, 2016) or skew bridges (Kalantari and Amjadian, 2010, 2011; Amjadian and Kalantari, 2012; Amjadian et al., 2016), have complicated dynamic characteristics compared to highway bridges with regular and symmetric geometry, such as straight bridges. There is no doubt that finite-element method (FEM) is the most reliable approach to dynamic analysis of structures, buildings (Nateghi-Alahi and Khazaei-Poul, 2012; Lu et al., 2015) and bridges (Tondini and Stojadinovic, 2012; Mondal and Prakash, 2016), with different types of materials and levels of computational complexity.…”

Eulerian-based virtual visual sensors to measure dynamic displacements of structures

“…Photogrammetry methods have been used in the measurement of static displacements and strains in bridges. More recently, digital image correlation and other block matching algorithms that use digital video data to measure static displacement fields with high accuracy have been explored . However, the computational cost of these methods is relatively high.…”

Effect of numerical soil-foundation-structure modeling on the seismic response of a tall bridge pier via pushover analysis

“…Regarding P-∆ and pounding effects, the rocking movement of the pile cap due to the SFS interaction is especially important for tall bridges. It should also be noted that the bridge superstructure may be subjected to considerable torsional moment due to the foundation rotation about its vertical axis during earthquakes caused by: (1) seismic loading conditions, as, e.g., bilateral seismic loading, torsional components of earthquake motions [14], [15], and spatial variation of the ground motions [6], [15]; (2) foundation conditions, as, e.g., non-uniform properties of the soil surrounding the foundation, geometrical configuration of the foundation, and partial damage or failure of the foundation [16]; (3) structural configuration, as, e.g., when the mass center and the center of rigidity of the structural system do not coincide [14] , and (4) collision of the bridge superstructure with abutments [17], [18] or adjacent spans [19]. Because of deck rotation about the vertical axis, the induced transverse movement may also lead to pounding and unseating of the superstructure.…”