240 © 2014 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin · Structural Concrete 15 (2014), No. 2 Technical Paper DOI: 10.1002/suco.201200020 The main objective of this investigation is to provide an alterna- tive method for the damage detection and assessment of bridge structures based on comparisons between finite element (FE) modelling/analysis and field data. The field data reported in this paper refers to the use of a non-destructive structural testing method (IBIS-S sensor system – displacement/movement-detec- tion sensors with interferometric capabilities) and visual inspec- tions. The FE models developed and presented in this study demonstrate certain degrees of reliability in terms of predicting the mechanical behaviour of the bridge structure under investi- gation. The FE models were developed using the ANSYS software package. This investigation also provides a detailed report on the application of the field survey that was carried out on a rather heavily used bridge located in Chatham, Kent, UK. The field data concerning the IBIS-S sensors correspond to subjecting the bridge to different static and dynamic loading conditions. The sta- tic and dynamic structural responses of the bridge were created by driving a lorry up and down the bridge. The same loading con- ditions were then simulated using the FE model developed to veri- fy the sensitivity of the model. This FE model was then used to study the response of the bridge to other loading conditions. It is believed that the proposed method could potentially be used for assessing bridge structures within the context of the health moni- toring of structures. Keywords: finite element modelling, bridge health monitoring, IBIS-S sensor, ANSYS 1 Introduction Finite element (FE) models usually need calibration to conform to experimental data. It is important to empha- size that establishing the difference between calibration and correlation is one of the objectives of this investiga- tion. The correlation process makes the FE model more accurate so that it can be synchronized with experimental data. In this process, the actual condition of the structure under investigation, with observed defects such as cracks and structural deformations (internally as well as external- ly), is introduced into the developed FE model in order to correlate it with the actual structure, in this particular case a bridge. The actual behaviour of structures can rarely be pre- dicted, even using FE methods. Numerous factors such as age, degradation of materials, corrosion and cracking can cause disparity between the results of an ideal FE model and the actual behaviour of the structure. Extensive re- search has been performed for the case of damage detec- tion/identification in bridge structures [1]. Some of these investigations apply analytical methods [2, 3] and others use non-destructive measurement methods. But a combi- nation of analytical modelling with experimental data col- lection [4, 5] has always provided the best results. In this investigation, the authors have tried to eliminate the dif- ference between the actual field data and the results of the analytical models by introducing the sources of these dis- parities into the FE models. This is called “correlation”. It is believed that this will provide an opportunity to develop reliable FE models that are capable of predicting the actu- al behaviour of a structure. The science of fracture mechanics has now branched into diverse state-of-the-art topics investigated by a wide variety of scientific specialists, with investigation results being applied to a broad range of problems [6]. These in- valuable findings provide a foundation on which new soft- ware can be developed, capable of solving problems such as stress concentration in a cracked surface in a fraction of a second [7]. The structure under investigation in this study is a four-span simply supported concrete deck bridge struc- ture, the Pentagon Road Bridge (Fig. 1), which has carried an access road from Rope Walk to the Pentagon Shopping Centre since 1975. The Pentagon Road Bridge consists of four spans, as shown in Fig. 2, supported on abutments at the extreme ends of the bridge and three intermediate piers. Starting Use of non-contact sensors (IBIS-S) and finite element methods in the assessment of bridge deck structures Amir M. Alani Morteza Aboutalebi* Gokhan Kilic * Corresponding author: am50@gre.ac.uk Submitted for review: 01 August 2012 Revised: 18 October 2013 Accepted for publication: 13 November 2013 Fig. 1. Aerial view of Pentagon Road Bridge (Google Earth, 2012)