Optimization of the seismic response of bridges using variable‐width joints

Abstract

An aspect of seismic design of bridges that has hardly received proper attention so far is the appropriate selection of joint gaps. End gaps define the boundary conditions of the bridge and affect its dynamic response; their proper design can lead to an improved structural performance under dynamic actions. The idea of the 'Dynamic Intelligent Bridge' is explored here, wherein current bridge joints that have a fixed width are substituted by variable-width joints and, under seismic loading, the joint gap is optimised either with a one-off adjustment, or continuously (in real time) through semi-active control. In all cases, a novel device is used that permits this improved behaviour of the joints, the moveable shear key (MSK), a device for blocking the movement of the bridge deck, which has the possibility to slide, hence varying the size of the existing joint gap. In this context, the effect of gap size on the seismic response of bridges is assessed herein and a methodology is put forward for optimising this size, using a number of criteria such as maintaining the functionality of the bridge for moderate earthquakes, and ensuring the safety of the bridge and its users under earthquakes stronger than that used for design.

A model-based damage identification framework for R/C bridges using vibrational measurements.

“…3, the left pier has a height of 7.9 m, and the right pier has a height of 9.3 m, due to the longitudinal slope of the bridge axis. The abutments of the bridge are seat-type with a backwall height equal to 2.5 m (Mikes and Kappos, 2023). In the abutment positions, the deck seats on two elastomeric bearings.…”

Modelling of the Full-Range Response of Abutment-Backfill Systems

“…The layout of the bridge model is shown in Figure 6. The case study bridge was subjected to a set of 7 spectrum-compatible artificial accelerograms parallel to its longitudinal direction, taken from a companion paper [11], scaled to vari-ous amplitudes of the design spectrum. The lowest level of seismic intensity considered was at PGA,rock = 0.32 g and the highest was at PGA,rock = 0.96 g (six times the design earthquake Ed), as backfill softening was found to occur for high intensities only.…”

“…However, lots of backwalls worldwide are stronger and have a more ductile behaviour, forming a plastic hinge at their bottom as they collide with the deck. Such behaviour is common in the seismic regions of Europe [10], [11] and also in bridges in seismic regions of the US that were designed before the implementation of the Caltrans guidelines [12]. Therefore, modelling methods that include nonlinear beamcolumn elements and soil springs to represent the structural parts of the abutment and the backfill soil, respectively, have been proposed (e.g.…”

A Damage Detection Approach to Assess the Performance Level of R/C Bridges Using Vibrational Response Measurements

“…Figure 3 illustrates that the left pier has a height of 7.9 m, while the right pier has a height of 9.3 m due to the longitudinal slope of the bridge axis. The abutments of the bridge are seat-type, with a backwall height of 2.5 m [14], [15]. At the abutment positions, the deck is supported by two elastomeric bearings.…”