Distributed dynamic fibre-optic strain monitoring of the behaviour of a skewed masonry arch railway bridge

Skewed masonry arch railway bridges are common, yet their structural behaviour under typical working loads, along with gradual changes in behaviour due to degradation, can be difficult to determine. This paper aims to address this problem through detailed monitoring of a damaged, skewed masonry arch railway bridge in the UK, which was recently repaired. A comprehensive Structural Health Monitoring system was installed, including an array of fibre-optic Fibre Bragg Grating (FBG) sensors to provide distributed sensing data across a large portion of the bridge. This FBG monitoring data is used, in this paper, to investigate the typical dynamic structural response of the skewed bridge in detail, and to quantify the sensitivity of this response to a range of variables. It is observed that the dynamic bridge response is sensitive to the time of day, which is a proxy for passenger loading, to the train speed, and to temperature. It is also observed that the sensitivity of the response to these variables can be local, in that the response can differ throughout the bridge and be affected by existing local damage. Identifying these trends is important to distinguish additional damage from other effects. The results are also used to evaluate some typical assumptions regarding bridge behaviour, which may be of interest to asset engineers working with skewed masonry arch bridges.

Wireless-Based Identification and Model Updating of a Skewed Highway Bridge for Structural Health Monitoring

Vibration-based monitoring was performed on a short-span skewed highway bridge on the basis of wireless measurements. By means of operational modal analysis, highly accurate modal results (frequencies and mode shapes) were extracted by using a self-developed wireless acquisition system, for which the performance was verified in the field. In order to reproduce the experimental modal characteristics, a refined finite element model was manually tuned to reduce the idealization errors and then updated with the sensitivity method to reduce the parametric errors. It was found that to build a reliable Finite element (FE) model for application in structural health monitoring, the effects of superelevation and boundary conditions of a skewed bridge should be taken into account carefully.

Dynamic Analysis of Two-lane Skewed Bridge and High-speed Train System

Bridges are vital in the operation of railway networks since any hindrances to their operation could suspend the flow of traffic. An important characteristic of bridges highly affecting their behavior is the skew angle. In this paper, a sensitivity analysis is performed to identify the effects of skew angle on train-track interaction for single- and double-sided crossings of a high-speed train. Comprehensive three-dimensional finite element models of the bridge and vehicle are developed, which are then calibrated using dynamic field test results. Effects of skew angle on shape modes and modal frequencies, acceleration values, and bridge displacement in various crossing speeds are studied. The results showed that if the bridge skew angle is more than 15°, it will affect the modal shape and frequency of the bridge. When the skew angle is less than 15°, the results of the bridge displacement are similar to those of the bridge with skew angle of zero. However, with the increase of the skew angle, the deformation value of the bridge decreases and the speed corresponding to the maximum displacement value also varies. Finally, the results of acceleration due to the speed and skew angle of the bridge are not the same in one-way and two-way passing states.

Rational Analysis for Understanding Skewed Steel Bridge Cross-Frame Behavior

<p>The design of skewed I-girder steel bridges is common throughout the country. Such bridges have been fabricated and constructed and have generally performed well. Where issues have been encountered, they were primarily related to bridge construction and, quite often to the torsional behavior of the severely skewed bridge superstructure. Until recently, there have been few analysis and design guidelines available to the structural designer on the construction engineering of the skewed I-girder bridges. AASHTO [1] specifies that the contract documents should state the fit condition for which the cross frames are detailed for I-girder bridges. Recommendations are also provided for the estimation of the cross frame locked-in forces. This paper presents a case study in a fit-up analysis of multi-span skewed I-girder steel bridge using 3D finite element method modeling. Fit-up analysis was carried out to evaluate girder’s web distortions, determine the cross- frames locked-in forces and compare them to the recent AASHTO’s recommendations. The paper should provide designers with a more detailed understanding of a bridge’s behavior in this condition as compared with the more generalized recommendations from AASHTO guidelines.</p>

Seismic margin assessment of a reinforced concrete skewed bridge in a nuclear power plant

This paper presents the seismic margin assessment of a reinforced concrete (RC) bridge using the high-confidence-of-low-probability-of-failure (HCLPF) value. An existing RC skewed bridge built in a nuclear power plant (NPP) in Korea was selected for studying objective. Finite element modeling of the bridge is developed in OpenSees, an open system for earthquake engineering simulation. The reference earthquakes applied for the probability analysis are selected from the set of generated ground motions that using for designing NPP structures in Korea. The HCLPF value is calculated based on the fragility method associated with the approximate second moment approach. The effect of randomness and uncertainty in demand and capacity variables is taken into account in the fragility analysis procedure. Based on the calculated HCLPF values, the seismic fragility assessment of the bridge can be readily implemented.