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2020
Thursday, August 27th
11:45 AM

A Numerical Analysis of Stone Masonry Arch Bridges and Structural Backing

Thomas Kerr, Department of Civil Engineering and Construction, Institute of Technology Sligo; National Roads Office, Drumlonagher, Donegal Town, Donegal
Tomás O'Flaherty, Department of Civil Engineering and Construction, Institute of Technology Sligo, Sligo

Cork Institute of Technology, Cork, Ireland

11:45 AM - 1:00 PM

Masonry arch bridges are a significant part of the transport network system in Ireland. Therefore, it is essential that we maintain the existing masonry bridge stock as a valuable asset and protect these bridges from a heritage viewpoint. The increased structural demands placed upon these bridges coupled with more sophisticated analysis methods have required and enabled a greater understanding of the response of masonry arch bridges to ever increasing traffic loading. When loaded, the structure acts in compression and the arched configuration enables the transmission of loads through the individual masonry units to the supporting piers or abutments. The stability of the arch primarily depends on the arch shape and the thickness of the arch barrel. However, compression enhancement can be achieved through the backfill material surrounding the arch, which also serves to distribute loads and to resist adverse tension inducing arch movements generated by the arch thrust. Selectively varying the quantity and constitutive parameters of the backfill is known to enhance arch capacity. In the past, structural backing was included to enhance the quality of arch construction and, where present, is generally located to the back of the abutments and to varying extents over the arch haunches. However, little is known of the contribution of structural backing to arch strength.

Case Study: Calculating Bridge Displacement from Accelerations for Load Assessment Calculations

Andrew Bunce, Civil Engineering, School of Natural and Built Environment, Queens University Belfast,
David Hester, School of Natural and Built Environment, Queen’s University Belfast
Su Taylor, School of Natural and Built Environment, Queen's University Belfast
James Brownjohn, Vibration Engineering Section, University of Exeter, UK
Yan Xu, Vibration Engineering Section, University of Exeter, UK

Cork Institute of Technology, Cork, Ireland

11:45 AM - 1:00 PM

Recovering displacement from accelerations has been demonstrated on bridges previously, with the main challenges being the presence of low frequency noise and the need for user-calibrated filters to overcome this. Therefor this paper presents a case study of a low-cost load test procedure, using bridge acceleration to calculate displacement. Typical approaches look use filtering or signal collecting methods to mitigate noise, however this study uses an aviation grade accelerometer to minimise noise in the acceleration signals and employs a quality control procedure to alert the user to the quality/reliability of the results. A live/open bridge is tested using a loaded and unloaded truck, and direct displacements are also recorded by linear variable displacement transducer (LDVT) and Imetrum camera displacement system to verify results. The calculated displacements from the integration procedure with varied loads are presented, with the quality indicators first being assessed before comparing to the directly measured displacements. This procedure may not be applicable to longer span bridges, or bridges where it is difficult to isolate quiet periods of traffic, however for this study the procedure worked well. Overall, the quality' indicators provided good insight into the accuracy of the calculated displacements and there was good agreement between the 3 measurement methods, with the magnitudes of errors experienced being around ±0.3mm.

Identifying Damage In A Bridge By Analysing Rotation Response To A Moving Load

Claire McGeown, School of Civil Engineering, University College Dublin
Farhad Huseynov, School of Civil Engineering, University College Dublin
David Hester, School of Natural and Built Environment, Queen’s University Belfast
Patrick McGetrick, School of Engineering, National University of Ireland, Galway
Eugene O'Brien, School of Civil Engineering, University College Dublin, Ireland
Vikram Pakrashi, Dynamical Systems and Risk Laboratory, School of Mechanical and Materials Engineering, University College Dublin

Cork Institute of Technology, Cork, Ireland

11:45 AM - 1:00 PM

A recent survey of Europe’s highway infrastructure has concluded that almost half of Europe’s bridges are nearing the end of their design live. Work in the wider Structural Health Monitoring sector is aiming to develop reliable and cost-effective methods for verifying condition, remaining service life and safety of ageing structures. Most bridge condition assessment methods are based on deflection, acceleration or strain measurements. This paper looks at the possibility of using rotation measurements as a main parameter to identify damage. This study looks at numerical analyses of a moving point load on a one-dimensional bridge model to provide the theoretical basis of the proposed damage detection method. It is shown that when local damage occurs, even when it is remote from a sensor location, it results in an increase in the magnitude of rotation measurements. This study looks at how best to exploit this fact for damage detection. In the study a number of damage scenarios and sensor locations are investigated, and their influence on the ability of the algorithm to detect damage are reported.

Probabilistic System Analysis – Practical Examples for Railway Bridges

Lorcan Connolly, Roughan & O'Donovan Innovative Solutions
Marko Duranovic, Roughan & O'Donovan Innovative Solutions
Róisín Donnelly, Roughan & O'Donovan Innovative Solutions

Cork Institute of Technology, Cork, Ireland

11:45 AM - 1:00 PM

The issue of maintenance of ageing bridges with insufficient budget allocations is well documented throughout Europe and beyond. To combat the issue of out of date assessment standards, insufficient structural information and deteriorating bridges, probabilistic assessment bridge techniques have evolved significantly over the past number of years. Previously, probabilistic analysis methods have been applied at the element level, where the highest element failure probability is assumed to govern for the structure. This fails to account for inherent redundancy which is often present in bridge structures. For example, the development of a plastic hinge due to elastic failure in a steel girder may not necessarily cause collapse of a structure. For this reason, system analysis approaches have been proposed which consider the actual probability of various collapse mechanisms. However, most of these studies have been based on purely theoretical models which fail to consider the complex 3D structural response of bridge structures, and are not applicable to structures subject to moving loads. This paper demonstrates a probabilistic system analysis approach for two case study railway bridges, one being based on codified live loading and another based on measured Weigh-In-Motion (WIM) data.

Validation Of Finite Element Light Rail Bridge Model Using Dynamic Bridge Deflection Measurement

Paraic Quirke, Murphy Surveys, Global House, Kilcullen Business Campus, Kilcullen, Co. Kildare
António Barrias, Arup, 50 Ringsend Road, Dublin

Cork Institute of Technology, Cork, Ireland

11:45 AM - 1:00 PM

Use of finite element modelling (FEM) to predict structural behaviour under static and dynamic loading conditions is a well-established aspect of the bridge design process. The Cherrywood Luas viaduct carries the Luas light rail system through proposed development lands at Cherrywood, South County Dublin. As part of development plans in the area it is proposed to create a new street adjacent and parallel to the existing viaduct with associated footpaths and landscaping. It is proposed to integrate the new structure supporting the street into the existing light rail bridge structure.