bluuebunny/crossref_metadata_2025 huggingface dataset:
Failures of external Tendons in Prestressed Concrete Bridges: Causes, Investigations, Remediation and Prevention.
Authors: Godart Bruno , Lacombe Jean-Michel , Aubagnac Christophe
Published: March 2016

In the the early 1980’s, an evolution in the grouting operations took place with the use of increasingly fluid grouts to facilitate the injection of the prestress ducts. During a gammagraphy campaign carried out on a box girder bridge under construction in 1994, anomalies were detected at the upper point of the ducts of the external prestressing tendons. Observations carried out after opening of some ducts highlighted a lack of filling and the presence of a product having the consistency of a wet and soft white paste. After presenting several cases of external tendon failures that occurred in the past years in France, the article describes the mechanism leading to severe grouting defects resulting in failures of tendons by a rather rapid corrosion. Then it presents the development of an investigation device based on dielectric capacity measurement that was applied during the campaign of investigations launched on all box girder bridges of the French national road network.
Changes in codes following structural failures: an Italian perspective on mitigation of structural vulnerability
Authors: Palmisano Fabrizio , Vitone Amedeo
Published: March 2016

In the last twenty years, forensic investigations of failures occurred in Italy have clearly highlighted that the increasing demand in society for economic growth has favoured the blooming of less conservative and even hazardous design and construction works.

After a short review of the Italian codes of practice dealing with structural vulnerability, some examples of structural vulnerability assessment in Italy is given in the article, with reference to both the large scale (i.e. the scale of the building) and the small (territorial/regional) scale.
Predicting structural disasters with Radar interferometry
Authors: Terwel Karel , Van Waning Henk , Hanssen Ramon
Published: March 2016

Radar interferometry is a technique which can observe the earth’s surface during day and night time. It makes uses of thousands of pulses per second that are transmitted by satellites and reflected by the surface of, for instance, structures. By analyzing the data it is possible to measure displacements of the surface within millimeter precision. For the building industry this might be a promising technique, for monitoring buildings or for forensic engineering. Variables that might be monitored are the displacements of roofs, of balconies or the settlements of buildings. In addition, the technique might be a tool which can be used for forensic investigations. This paper will discuss the possibilities and limitations of radar interferometry for both building monitoring and forensic engineering. The method is expected to be especially useful for measuring soil displacements and the resulting settlements of structures.
Forensics of a Partially Collapsed Timber Roof
Authors: Zwicky Daia
Published: March 2016

The roofing of an office building partially collapsed after being in use for almost twelve years. The author was appointed as an independent structural expert to investigate the damage event, by approval of all involved parties, i.e. owner, building insurer and roof constructor. The expert report should give answers to several questions related to forensic engineering, e.g. reasons for the partial failure of the roof elements; influence of the snow load present at the moment of partial collapse; faults or deficits in the structural concept, in element production or execution etc. The paper reports on the course of events and actions, the structural and architectural conception of the roofing, its structural behavior, determination of updated failure loads, associated structural safety assessment and degrees of compliance. The paper gives no conclusion on legal or insurance issues.
Risk Assessment for Interaction Effect of Adjacent High-Speed Railway Bridges and Highways
Authors: Ma Rujin , Tian Yu , Hu Xiaohong
Published: March 2016

In China, massive high-speed railway construction had been implemented in recent ten years. Due to the restriction of various factors, high-speed railway routes are usually located in existing transport corridors, which results in newly-built high-speed railway bridge (HSRB) being adjacent to and parallel to the existing highway. However, interaction between adjacent high-speed railway bridges and highway and its effects to the safety of bridge structure and the driving safety of high- speed trains and vehicles is not yet clarified. In this paper, risk assessment for interaction effect of adjacent and parallel high-speed railway bridge and highway is introduced. Firstly, risk factors due to the closely arranged high-speed railway bridge and highway, which may affect the safety of bridge structures, high speed trains and vehicles, are discerned. On this basis, general framework of assessment process is established. Subsequently, through a case study, effects and consequences of each risk factor are investigated by means of theoretical analysis, numerical simulation and field measurement. Analysis results show that the immediate vicinity of high-speed railway bridge and highway challenge the safety of bridge structure and the operation of railway and highway. Furthermore, risk evaluation and assessment of each risk factor are addressed through risk matrix method considering probability of occurrence and consequence comprehensively. In the end, a variety of risk mitigation measures are suggested.
Structural robustness assessment of concrete frames considering membrane action effects
Authors: Botte Wouter , Caspeele Robby , Taerwe Luc
Published: March 2016

One way to increase the structural robustness is to take into account membrane action effects in beams and slabs. This membrane action generates an additional load transfer to neighbouring supports, which can considerably increase the load-carrying capacity of the member under consideration. However, the effect of membrane action on commonly used robustness indicators is still unknown. In previous contributions of the authors, a numerical model for reinforced concrete slabs and beams under large deformations was developed and validated. In this contribution, a framework is developed in order to incorporate this numerical model in the analysis of a simple concrete frame in case of column loss, in order to assess the influence of membrane action on commonly used robustness indicators.
Probabilistic structural assessment of railway masonry arch bridges
Authors: Moreira Vicente , Matos José , Oliveira Daniel
Published: March 2016

Most of masonry arch bridges dates from ancient times, having an important historical value to society, thus requiring appropriate conservation approaches. Regarding masonry arch bridge’s structural condition, considering its age, and consequently deterioration, and the fact that they are submitted to loads much higher than those existing at their construction period, it is imperative to evaluate the structural performance of these structures. This paper will expose a methodology for safety assessment of masonry arch bridges, namely in terms of ultimate load- carrying capacity, determined by limit analysis. Monitoring and material characterization are standard procedures in safety assessment and, will be shown that Bayesian techniques are a useful tool to incorporate new gathered information in structural analysis model. Safety assessment procedures described in the article will be applied to a Portuguese stone masonry arch bridge from the 19th century.
Reliability Design for Reinforced Concrete Structural Elements based on Statistical Characteristics of Local Live Loads
Authors: AlSanad Shaikha , Assakkaf Ibrahim
Published: March 2016

The main purpose of engineering design, in general is to insure safety, functional, and performance requirements of a structural component and/or system for target reliability levels or indices, for specified time frame, and for a specified environment. As this must be accomplished under conditions of uncertainty, probabilistic analyses are necessary in the development of such reliability-based design of R/C structural elements. There are numerous reasons for developing a specific structural design for a certain region or a country. Many countries have adopted various alien design code standards that were based on a mixture of various well-established international traditional and/or reliability-based codes in the construction of reinforced concrete R/C structures. Because these code standards were not developed for local conditions and environment in these countries, they are deemed to be less adequate to provide the proper requirements for long-term robust and durability of the R/C structural components.

The paper will address the detailed procedures and focus on the design of R/C elements and components using reliability methods and approaches, namely reliability of structural components. Reliability of a whole concrete structure or system such as a building or a bridge can be explored in the future, and can be based on this paper using the approach called “Systems Reliability.” In this paper, reliability-based partial safety factors (PSF’s) for R/C structural elements will be determined based on local live load statistics. The first-order reliability method (FORM) will be used to compute the Partial Safety Factors (PSF’s) for specified reliability indices. These factors can be used in the Load and Resistance Factor Design (LRFD) formats to account for the uncertainties in strength and load effects. Adequate samples of live load intensities will be collected from various types of structures such as a building, library, factory, etc.; in the State of Kuwait to quantify the statistical characteristics of live load that are needed in the reliability analysis. The FORM procedure will be utilized to determine these partial safety factors based on probabilistic characteristics of strength and load effects pertinent to Kuwait region
Analysis of a heavy goods vehicle fire in wind conditions and its impact on structural performance of a cable-stayed bridge
Authors: Ma Rujin , Ma Minglei , Chen Airong
Published: March 2016

With growing concern over the fire risk of bridges, an analysis of temperature fields of heavy goods vehicle (HGV) and the impacts on bridge structure was conducted, by taking a cable-stayed bridge as a research object. With the test data of HGV fire in the Runehamar tunnel in Norway, the HGV fire model was obtained with numerical simulation. Using this model, the flame temperatures of HGV fire on the bridge deck were acquired at wind velocities of 0 m/s, 2.5 m/s and 5 m/s respectively. Considering the heat transfer characteristics of fire, the temperatures of stay cables were also achieved, and then the failures of stay cables were studied. After that, the safety assessment of bridge was conducted. The results show that the wind could reduce the damage of stay cables caused by fire. And the HGV fire has limited influence on the overall safety performance of bridge, but will pose a serious threat to the reliability and durability of bridge. So it’s necessary to take effective measures to reduce the loss caused by fire.
Buckling Temperature and Buckling Stress of a Steel Member with Lateral Bracing Caused by a Thermal Load
Authors: Nishino Takayoshi
Published: March 2016

This paper deals with the buckling of a slender steel member with lateral bracing. The buckling phenomenon is buckling by a thermal load, not by an external force. The buckling quantities of interest are the buckling temperature and the buckling stress. A theoretical method to obtain the relations between these quantities and the bracing rigidity is shown in this paper.
Predictive testing for heat-induced spalling of concrete
Authors: Rickard Ieuan , Maluk Cristián , Bisby Luke , Deeny Susan
Published: March 2016

This paper describes a project which sets out to define a practical predictive test method for heat- induced explosive spalling of concrete. The method is based on a novel testing apparatus known as the Heat-Transfer Rate Inducing System (H-TRIS), previously developed at The University of Edinburgh. A series of 75 samples were tested using a large-scale standard fire testing furnace at CERIB (France) and using H-TRIS in Edinburgh. Within the scope of this project, a thorough examination of the thermal exposure was carried out in order to ensure repeatability of the thermal exposure imposed during testing. The H-TRIS method and apparatus was successful in accurately replicating the thermal exposures experienced by samples in the fire testing furnace when testing to both the ISO 834 and modified hydrocarbon (HCM) standard fire curves. The testing has also provided insights into the influence of sample size, polypropylene fibre content, and moisture content on the propensity for heat-induced concrete spalling.
Deterioration Prediction of Infrastructures with Time Series Data Considering Long Memory Effect
Authors: Kitaura Naoki , Kaito Kiyoyuki
Published: March 2016

In order to compensate for shortcomings of asset management based on visual inspection data, asset management based monitoring data has got a lot of attention. However, there is little methodology to apply time series data to conduct a decision making on asset management. In addition, long-term monitoring data of infrastructure have long memory effect because the deterioration of gradually progress owing to accumulating various deterioration factors such as traffic load, weathering, anti-freezing agent and etc. In this study, the authors propose ARFIMAX- GARCH (Autoregressive Fractional Integrated Moving average with eXogenous variables- Generalized Autoregressive Conditional Heteroskedaticity) model and attempt to demonstrate the applicability of the proposed model by studying concrete application cases.
Minimization of Life Cycle Cost for Bridge Asset Management with Multi Stage Optimization
Authors: Furuta Hitoshi , Nomura Yasutoshi , Nakatsu Koichiro , Ishibashi Ken , Kagawa Yoshiaki
Published: March 2016

The purpose of this study is to minimize life cycle cost (LCC) for bridge asset management. This study attempts to develop an optimization method for bridge maintenance planning. It is realistically difficult to keep the safety level of all bridges within a limited budget. Furthermore, a local government needs to manage a large number of bridges. These cause the difficulty of optimization such as the increase of the number of bridges and strict constraint conditions. However, an optimization of maintenance plan for multiple bridges is significant to decrease an annual total cost. Hence, this paper proposes a new method to formulate a maintenance plan, which has the flexibility against uncertainties that involve the change of schedule, by multi-stage optimization that consider an appropriate budget allocation based on each bridge’s importance. Several numerical examples are presented to demonstrate the effectiveness for the planning of LCC minimized maintenance.
Cross-asset risk assessment (X-ARA)
Authors: Spielhofer Roland , Vajdic Nevena , Cirilovic Jelena , Mladenovic Goran.
Published: March 2016

This paper presents an outline of the CEDR Transnational Road Research Programme funded research project “X-ARA – cross asset risk assessment”. Objective and scope of the project are described and the approach is outlined. The main part of this paper presents the findings of a desk study, carried out during the project, on literature related to risk assessment in asset management and the current practice on risk assessment of several European road operators.
Integration of cross asset risk assessment into road infrastructure asset management
Authors: Weninger-Vycudil Alfred , Spielhofer Roland , Britton Chris , Oldfield Mark , Brozek Barbara
Published: March 2016

The CEDR-project “X-ARA – Cross-Asset-Risk-Assessment” aims at the development of a comprehensive risk assessment framework for the network level assessment of asset risks and impacts. Based on asset-specific risk assessment (pavements, structures, drainage, etc.) a procedure for the transformation and accumulation of these risks onto network level is an essential part of the project. X-ARA will enable a road administration to execute a risk-based assessment and comparison of different maintenance strategies on network level, and then “overlay” the effects of broad influencing factors to assess “what if” outcomes. In considering a “bottom-up” approach (from object level to network-level) the risk can be calculated and finally cumulated by using asset-specific information, which are available for most of the European road administrations.
Comprehensive Evaluation Method for Deterioration of RC Slabs
Authors: Mizutani Daijiro , Kaito Kiyoyuki
Published: March 2016

In RC slabs, a span consists of multiple panels and inspection data are accumulated in panel units (inspection units) but repair sections are extracted in span units (repair units). In this paper, an aggregative deterioration process model is proposed to evaluate deterioration conditions in the repair unit based on information of condition states obtained in multiple inspection units by statistical and stochastic methods (i.e. a Markov chain model, hazard models and a multinomial distribution). The authors carry out the detailed deterioration forecasting in the inspection unit. Therefore, a risk indicator in repair units can be defined without omission of information in inspection units by utilizing the proposed model. The risk indicator enables a life cycle cost analysis and a relative evaluation among repair units. Lastly, the effectiveness of the proposed method can be discussed through the case study targeting RC slabs of an actual expressway.
Evaluation method of bridge performance for new bridge asset management considering renewal of existed bridges
Authors: Masaki Ushiro , Jidou Mitsuru
Published: March 2016

In order to maintain the expressway bridge assets based on minimum LCC principle, Hanshin expressway has been developed a bridge management system (H-BMS: Hanshin expressway Bridge Management System) with an estimation system module of bridge condition state by integrated inspection data and a policy making module predicting maintenance budget, repair priority, etc. With the increase of aging structure, the H-BMS should be improved to take into account of drastic large-scale renewal policy from the long term point of view. This paper shows the methodology for calculating performance based soundness indicator as a basic analysis toward development of the new H-BMS.
Experimental and analytical study on stress concentration of corroded bridge wires
Authors: Miyachi Kazuhiro , Nakamura Shunichi
Published: March 2016

The wire specimens with artificial pits whose sizes were decided by the measured corrosion pit data. Three different pit shapes were assumed: round, triangle and triangle with a notch. Stress concentration factor at the sharp edge of pits were obtained by strain gauge measurement and 3D FEM analysis. Both methods showed that strain was almost same value and stress concentration is larger for sharper pit shapes.
Performance of existing concrete arch bridges
Authors: Mandić Ivanković Ana , Srbić Mladen , Franetović Marin
Published: March 2016

Numerous issues, including structural, environmental and economic indicators, that are to be considered in order to achieve efficient and effective performance of existing concrete arch bridge will be systematized and elaborated in this paper through the examples of several Croatian Adriatic arch bridges.
Assessment of existing composite bridges in New Zealand
Authors: Hicks Stephen , McKenzie Chloe , Lloyd Nigel , Graham Kenyon , Clifton G. Charles
Published: March 2016

Historically, numerous shear connector types other than headed stud connectors have been used in steel-concrete composite bridges within New Zealand. This paper presents interim results from a two year research programme that is developing new design and load assessment criteria for existing composite road bridges. The research consists of an investigation of as-built records and an evaluation of historical material strengths, prior to new design rules being developed that will be validated against existing test data to ensure that the required margins of safety are being maintained. It is hoped that the resulting design and assessment guidance will lead to improved load capacities for existing bridges, which will significantly increase the efficiency of the existing highway network, thereby opening it up to heavier 50MAX and high productivity motor vehicles (HMPV).
Probabilistic-based nonlinear analysis of a reinforced concrete railway bridge
Authors: Fernandes João , Matos José C. , Oliveira Daniel V.
Published: March 2016

The safety evaluation of structures comprises several factors to assess their condition state. However, the global safety of structures cannot be reached at all because there are many uncertainties sources. Due to all these uncertainties, the wisest way to deal with this problem is to assume all of these uncertainties as random variables and perform a reliability analysis, which is a probabilistic analysis, in order to obtain a reliability index that can give the structure condition. This paper presents the nonlinear analysis of an existent reinforced concrete railway bridge, with DIANA software. The developed model will be used in a probabilistic based approach in order to obtain a global reliability index, which is then compared with a threshold value in order to evaluate the bridge condition.
EIC-based fatigue life prediction for aging reinforced concrete beams
Authors: Ma Yafei , Wang Lei , Zhang Jianren , Liu Yongming
Published: March 2016

The relationship between corrosion pit depth and corrosion loss is investigated based on the experimental results from artificially corrosion test. A calibration process is used to obtain an empirical stress concentration factor model under different corrosion levels based on experimental fatigue tests. It is found that the stress concentration factor increases initially and then decreases with increasing corrosion loss. Following that, the developed model is used to obtain the stress intensity factor. The fatigue life can be predicted by using integration of the fatigue crack growth rate curve from the equivalent initial crack to a critical length. Numerical fatigue life prediction results for fatigue tests of various corroded beams are used to demonstrate the accuracy of the propose method, and reasonable agreement is observed.
Experimental study on static behavior of damaged RC arch ribs
Authors: Zhang Jianren , Ma Yafei , Liu Binbin , Wang Lei
Published: March 2016

An experimental study is proposed to investigate the effects of corrosion-induced cracking damage on the static behavior of corroded RC arch ribs. Four circular RC arch ribs (an uncorroded arch rib and three accelerated corroded arch ribs) are designed and made in the laboratory conditions. The concrete cracking and section damage induced by corrosion is discussed in detail with experimental observations. Following this, a five-loading test is conducted, and the propagation of cracks, the load-displacement response, the ultimate load bearing capacity and the failure modes of arch ribs are presented.
Structural Assessment of Existing Concrete Bridges: A Consulting Engineers´ point of view
Authors: Müllers Ingo , Nawabi Assad
Published: March 2016

Germany is located in the centre of Europe and its economy is highly linked with its neighbouring countries. Germany’s highway network is - to a high degree - built on concrete bridges, which were mostly constructed and designed between 1965 and 1985. These existing concrete bridges do not per se fulfil the current requirements regarding the used materials or the possible ultimate load. Therefore, the German government has started different programs to verify existing concrete bridges, e.g. regarding: fatigue of coupling joints, stress corrosion cracking and general verification regarding higher traffic loads. The authors of this conference paper describe just the mentioned problems and show examples of their own consulting experience. With these examples they want to show that sometimes not the changed codes are the reason for important differences between the original design and the verification but rather different static models or human errors.
Analysing Concrete Structures - Advances in Material Modelling with Practical Applications
Authors: Rhodes Steve , Icke Philip , Lyons Paul
Published: March 2016

Numerical models for concrete have been in development for more than three decades. The advances in recent years, along with the arrival of powerful computers on the desks of consulting engineers, mean that this technology can now be regarded as a practical tool for use in industry, rather than only a research tool.

A simple example is used to demonstrate the use of a modern concrete material model with different idealisation approaches, 2D and 3D, allowing comparison to hand methods such as member resistances to EN1992-1-1.
Shear strength evaluation of RC bridge deck slabs according to CSCT with multi – layered shell elements and PARC-CL Crack Model
Authors: Belletti Beatrice , Scolari Matteo , Muttoni Aurelio , Cantone Raffaele
Published: March 2016

The shear resistance of RC slabs without shear reinforcement subjected to concentrated loads near linear support is usually calibrated on the base of tests on one – way slabs with rectangular cross section. However, the actual behavior of slabs subjected to concentrated loads is described properly by a two-way slab response. The aim of this paper consists in the evaluation of the shear resistance of bridge deck slabs using analytical formulations and Nonlinear Finite Element Analyses (NLFEA). The obtained numerical results are consequently compared with experimental observations from two test campaigns. The case studies were analysed by NLFE analyses carried out using the constitutive Crack Model PARC_CL (Physical Approach for Reinforced Concrete under Cycling Loading) implemented in the user subroutine UMAT.for in Abaqus Code. In order to predict properly global and local failure modes through a NLFE model, a multi – layered shell modelling has been used. As shell element modelling is not able to detect out – of – plane shear failures, the ultimate shear resistance of these slabs is evaluated by means of a post – processing method according to the Critical Shear Crack Theory (CSCT).
Performance assessment of concrete structures based on probabilistic prediction models and monitoring information
Authors: Strauss Alfred , Zambon Ivan , Vidovic Anja , Bergmeister Konrad , Frangopol Dan
Published: March 2016

An efficient evaluation and prediction of mechanical and chemical degradation processes is fundamental requirement for life-cycle analysis as well as for the complete assessment of concrete structures. Important tools and valuable support in these tasks are inspection systems and monitoring methods. Unfortunately, due to their practical feasibility and costs they entail, their applicability is limited. Hence, information gathered with inspection and monitoring methods need to be used in the most effective manner The aim of this paper is to present a framework for the prediction of time-dependent performance indicators of concrete structures prone to fatigue, with emphasis on a wind turbine foundation. A theoretical background with selected indicators is presented through associated life-cycle prediction methods including inspection and monitoring information with incorporated reliability.
Study on Full-scale Bending Experiment of Concrete Girder Reinforced by Steel Plate and Concrete Composite Strengthening Method
Authors: Wang Qian , Li Rui , Luo Qiao , Qu Tian-Yu , Wang Chun-Sheng
Published: March 2016

Concrete bridges often have damages after opening to traffic for several years, it is necessary to reinforce the bridges in order to ensure the safety and extend the service life of the bridges. The steel plate and concrete composite strengthening (SPCCS) is a new retrofit technique, it works through welding studs on the reinforcing steel plates, planting steel bars in the original concrete, and casting concrete between the original structure and the steel plates, thus the new and existing concrete can work together. The strengthened structure has the advantages of high bearing capacity, large stiffness and long term durability. In order to investigate the mechanical performance of the strengthened bridge, a full-scale damaged box girder released from an actual bridge was reinforced by SPCCS technique. The bending resistance test was carried out and the test results were analyzed in this article. On the basis of the test, the SPCCS technique was applied to reinforce a damaged bridge. From the field test data, it showed that the bend resistance of the bridge was increased a lot after reinforcement. The SPCCS technique is an effective method to reinforce the concrete bridge, which can help realizing the sustainable maintenance of the bridge.
Preserving the Service Life of a Bridge Threatened with Fatigue Cracking
Authors: Murillo Juan A. , Nakhaei Mofid , Bougacha Samir
Published: March 2016

The IH-345 viaduct in downtown Dallas, Texas, has experienced fatigue cracking that resulted in 20 years of increased inspection, monitoring, and repair of the steel superstructure. The steel framework is made of mainly longitudinal girders and transverse floor beams. This article addresses advancement in structural engineering as a practical solution of reaching beyond the codified provisions for design, evaluation, and rehabilitation of highway steel bridges using advanced analytical methods. Finite Element models, calibrated to field instrumentation results through strain/displacement measurements for specific truck loading, were used to analyze the structural performance, find the crack formation mechanisms, and ultimately develop retrofit schemes.
Demolishment of a post-tensioned concrete viaduct across a motorway in Almere, The Netherlands
Authors: Boeters Ton , Vergoossen Rob , van den Brink Tewis
Published: March 2016

In Western Europe there are many concrete bridges and viaducts which were built 35 years or more ago. Although most of these concrete structures can be maintained, some structures become functionally obsolete. Because of the strongly increased traffic between Amsterdam and Almere, the Motorway A1 and A6 will be widened in the next years. Overpass “Havendreef” spans motorway A6 and is one of the structures which need to be replaced in order to realise the wider motorway underneath. This two span viaduct consists of a post-tensioned concrete slab with a varying construction depth.

Many difficulties were encountered in this project from an engineering point of view. How to deal with a lack of structural information? What is the structural behaviour of the post-tensioned cables after cutting? Which part could structurally be demolished in the first phase and which in the second?

Because the penalties for traffic hindrance due to construction are strict, the overpass had to be demolished as fast as possible, whilst underneath one span the traffic flow was undisturbed.
Cleaning Technique for Repair Painting on a Weathering Steel Bridge
Authors: Takai Yuki , Aoki Yasumoto , Tsukamoto Shigeaki
Published: March 2016

A weathering steel bridge of the Kita-Kobe Route of the Hanshin Expressway exhibited severe salt adhesion and corrosion caused by salt water leaking through a narrow gap between parallel bridge. The damage resulted in the formation of the poor and heavy rust on the constantly wet surfaces by the use of de-icing salt during winter. Although the current practice recommends shot- blast cleaning for repair painting on weathering steel, the technique has not been standardized due to lack of practical experiences. This study shows that an appropriate combination of power tool cleaning and shot-blast cleaning followed by water cleaning can achieve satisfactory cleaning results without affecting the primary painting.
Using measurement to reduce model uncertainty for better predictions
Authors: Pasquier Romain , Smith Ian F. C.
Published: March 2016

Accurate models of real behaviour that are determined through measurements help engineers avoid expensive interventions and structural replacement. Model calibration by “curve-fitting” measurements to predictions is not appropriate for full-scale structures. This paper compares two population methods that can include modelling and measurement uncertainties using a simple example of a one-span beam. Standard applications of Bayesian inference that involve assumptions of independent zero-mean Gaussian distributions may not lead to accurate predictions, particularly when extrapolating. Another method, error-domain model falsification provides more reliable, albeit more approximate, predictions – especially when prediction is extrapolation. An example of a full-scale bridge illustrates the usefulness of the methodology in a real situation through improvements to fatigue-life estimates compared with design-type calculations without measurements.
A methodology based on temperature monitoring to reduce fire risk in tunnels
Authors: Rinaudo Paula , Payá Zaforteza Ignacio , Calderón García Pedro
Published: March 2016

The monitoring of temperatures during a tunnel fire is of major importance for both, the fire- fighters and the engineers in charge of undertaking the repair works. However, current methods commonly used in assessing fire damage have limitations when applied to tunnels, and only provide an estimation of the maximum temperatures caused by the fire. The temperature-time curves associated to the fire event should be used to properly assess the residual strength of the structure of the tunnel which is the key parameter to define the repair works, the time the tunnel will be closed and, therefore, the socio-economic cost of the fire. In addition the availability of temperature-time curves on real-time would provide very valuable information for the fire- fighters in charge of the fire extinction works. This paper presents a new general methodology for the optimal placement of sensors in a tunnel to obtain the evolution of the temperatures with time at any point of the tunnel linings.
Large-area electronics combined with integrated circuits into a strain sensing sheets
Authors: Yao Yao , Tung Shue-Ting , Verma Naveen , Wagner Sigurd , Sturm James , Glisic Branko
Published: March 2016

The strain sensing sheet based on Large Area Electronics (LAE) and Integrated Circuits (ICs) is being researched and developed at Princeton University. The prototypes of components of the sensing sheet including LAE interconnect, embedded sensors, batteries, and power harvesters have been created. Behaviour of the sensor exposed to damage has been studied and characterized. Probabilistic algorithms have been created for both data interpretation and evaluation of probability of detection. Small-scale and large-scale tests have been successfully carried out in order to evaluate the concept of the strain sensing sheet and understand its behavior under conditions of damage occurrence and propagation. The concept of the strain sensing sheet, test results, and its current state of advancement are presented in this paper.
Dealing with the peculiarities of the structural system identification of cable-stayed bridges by observability techniques
Authors: Lozano Galant Jose Antonio , Nogal Maria , Castillo Enrique , Turmo José
Published: March 2016

Traditionally, the structural response of a bridge is modelled by simplistic physics-based models in which the mechanical and geometrical properties are assumed as known. Nevertheless, this is not the case in most actual structures where the values of the actual properties are unknown due to uncertainties in the materials, in the construction methods or in the stress state. In some cases, a calibration of the computer models using monitoring information of the actual structure is required to improve the accuracy of the predicted structural response. To carry out this task Structural System Identification (SSI) methods can be used.

Recently, the authors proposed a promising static SSI method based on observability techniques. This method addressed the problems appearing when unknown parameters are assumed into the stiffness matrix of a structure. The observability method was efficiently applied to deal with simple structures, such as single and multiple span beams. Nevertheless, the presented works did not address the peculiarities appearing in complex structures with different load-bearing elements, such as cable-stayed bridges.

To fill this gap, this paper proposes the first application of observability techniques to deal with the SSI of cable-stayed bridges. This work enables the definition of the set of deflections and rotations which should be measured on site to identify a certain set of unknown mechanical properties in the deck, the pylon and the stay cables. A set of academic examples, of growing complexity, are used to explain the role that the inclination and cracking of the load-bearing elements of a cable-stayed bridge plays in the SSI by observability techniques. The results obtained in these academic structures are validated by more complex models of real cable-stayed bridges.
Monitoring of reinforced concrete bridges retrofitted by external tendons
Authors: Novák Balthasar , Boros Vazul , Koster Gerhard
Published: March 2016

Present traffic loads on bridges often exceed the actions anticipated at the time of construction. In Germany several prestressed concrete bridges with deficits in their load bearing capacity had been identified. An established retrofitting method is the installation of external tendons with deviation and anchorage blocks. Since the later proved to be a critical detail, their structural behaviour was monitored for three bridges in Hessen. The anchorage blocks were fitted with extensometers, strain gauges were installed on prestressing rods and the temperature was recorded. Also alert protocols were established, to detect potentially hazardous situations. The effects of different construction stages were tracked. The influence of short- and long-term temperature changes on the readings was assessed. In summary, the monitoring provided valuable insights into the structural interaction between the existing superstructure and the elements of the retrofitting.
Monitoring of strain cycles on a railway bridge with a wireless sensor network
Authors: Feltrin Glauco , Popovic Nemanja
Published: March 2016

Cross girders of a riveted steel frame bridge were monitored with a wireless sensor network. Since strain sensing is very expensive in terms of power consumption a novel signal conditioning hardware was developed that enabled to significantly reduce the power consumption. An embedded data processing algorithm transformed the recorded raw data into a sequence of maxima and minima representing the strain cycles thus reducing data communication and enabling an additional energy saving. By using a software based event triggering algorithm the embedded data processing was performed only for data acquired during train transits. Strain cycles of more than 900 trains were recorded. The quality of the recorded data was very good and demonstrated that WSNs can be a competitive alternative to conventional tethered monitoring systems for recording operational data for fatigue assessment of steel railway bridges.
Measurement and Reproductive Analysis of Vibration Characteristics of Structures Using Running Train
Authors: Hirabayashi Masaya , Sasaki Naomi , Ito Yuka , Kobayashi Kaoru
Published: March 2016

Using excited vibrations by running trains, the measurements of characteristics of RC rigid-frame structures with spread foundation were carried out. In this measurement, the damping ratios varied from 2.66% to 6.50%, although the measured structure was same. Although the previous studies indicated the interrelation between the height and the frequency of structures, and the interrelation between damping ratio and frequency of structures, these interrelations were not disclosed in this measurement. Moreover, train running FEM analyses with whole model with appropriate constitutive laws were carried out to reproduce the measured vibrations. The parametrical study of structure’s damping ratio, whole model’s frequency, damping ratio and vibration wave shape were almost same as the measured ones. As a result, by applying proper constitutive law and damping ratio of the structure, vibration characteristics and vibration behaviour of structure could be evaluated.
Damage Detection using Neutral Axis and Prestressing Force Distribution
Authors: Abdel-Jaber Hiba , Sigurdardottir Dorotea , Glisic Branko
Published: March 2016

Identification (i.e., detection, localization and quantification) of unusual structural behaviors of bridges represents an important aim of structural health monitoring (SHM). This paper proposes an SHM methodology based on loose structural analysis and on strain and temperature SHM data acquired by long-gauge fiber optic sensors. Pairs of long-gauge sensors are placed at key locations along a beam-like structure parallel to the centroid line. The position of neutral axis is evaluated from strain measurements using a novel algorithm. Change in the position of the neutral axis is then used to identify unusual behaviors that result in change in the position of the centroid of stiffness, such as partial loss of stiffness (e.g. damage). Effectiveness of prestressing force transfer is evaluated with another novel algorithm. The methodology was applied to two structures and successfully identified unusual structural behaviors.
Static and Dynamic Properties of Structures measured by Terrestrial Microwave Interferometry
Authors: Becker Matthias , Pullamthara Jiny Jose , Schneider Jens , Firus Andrei , Drass Michael
Published: March 2016

Terrestrial microwave interferometry is a sophisticated technique in geodesy to measure relative displacements of a structure with a high accuracy of up to 0,01 mm at a sampling rate of 200 Hz from a distance of up to 1000 m. One of the big advantages of the method is that the object to be measured does not have to be instrumented or walked-on as the microwaves are reflected by its surfaces and edges. In combination with structural analysis, the in-situ measurements can give a strong support for the condition assessment for a variety of structures in civil engineering and for validating their structural behaviour, robustness and safety. Examples of full-scale measurements of railway bridges and wind turbines will be presented in this paper.
Probabilistic Assessment of Structural Condition Incorporating Uncertainty of Measured Data through Multi-model Identification
Authors: Kim Hyun-Joong , Koh Hyun-Moo , Song Junho , Park Wonsuk
Published: March 2016

This paper proposes a novel procedure of probabilistic assessment of structural condition by incorporating uncertainty of measured data. Multiple FE models are updated through the successive optimizations which use probability distribution functions representing uncertainty of the measured data. In addition, twomachine-learningalgorithms are implemented for probabilistic description and classification of the updated multiple FE models. Principal Component Analysis (PCA) method transforms the updated FE models onto the principal subspace. Accordingly, distribution feature is better represented. Next, Gaussian mixture model is used to identify probabilistic features of the updated FE models. Finally, the probabilistic information about structural condition is obtained by using the updated FE models and the identified probability models. The proposed procedure is demonstrated by applying to assessment of Yeondae Bridge, a 4-span continuous steel-box girder bridge in South Korea. Through the proposed procedure, distribution of rating factors, which represent the probabilistic information about structural condition, is estimated. Especially, clustering-based model selection procedure enables more reliable assessment of structural condition even when higher uncertainty of measured data is associated.
Defect detection in strand wires within the anchorage area of high tensioned cables
Authors: De Wit Marcel , Hovhanessian Gilles
Published: March 2016

Assessment of cables of cable supported structures is complicated there these elements are often difficult to inspect visually. Owners of these kind of structures are facing a lack of information on these key elements of their structures.

This paper presents a new promising technology that can provide a solution for this problem by providing information on the condition of the cables inside the anchorage area.

In general the anchorage areas of cables is the most vulnerable part of cables due to water ingress, lower protection of the wires and fatigue issues. Typical defects in these areas are corrosion, cross section loss and wire breaks.

The development of this technology over the past years in cooperation with the French National Laboratory IFSTTAR has resulted in a fully proven and operational tool that recently demonstrated its value on a full scale application on one of world’s largest stay Cable Bridge where it successfully assessed the condition of the cables behind the bottom anchorage. Over 80 000 wires have been inspected for defects on this project. Other structural owners have acknowledged the value of the technology by testing their cable anchorages.

The technology is based on Ultrasonic guided waves principle transmitted along a single wire of a 7 x 5 wire strand. This paper explains the principle of the technology, shows how it can be deployed on site, and provide feedback from lab tests and real measurement on site.
Application of non-destructive test on self-compacting concrete
Authors: El Mir Abdulkader , Nehme Salem G.
Published: March 2016

Durability, safety and performance are the target today in structure assessment for a reliable diagnostic method. The development of Self-compacting concrete (SCC) is increasing gradually to fulfil many aspects of construction industry. Therefore, durability properties still need some enhancements particularly in term of microstructure properties. Furthermore, there is a lack of research on non-destructive testing (NDT) on SCC. Question arises: are the contexts on the strength of normal concrete (NC) extendable on of SCC? Laboratory tests were performed at the BME, Department of Construction Materials and Technologies. Aim of the research is to determine the level of reliability of NDT on SCC with respect to NC. Constant and variable parameters were determined to the concrete mixtures. Constant parameters were: Type of cement and grading curve of the aggregate. Variable parameters were: Water-cement ratio, supplementary cementitious materials (SCMs) and limestone content. A statistical analysis was applied in order to understand the level of reliability of such measuring techniques on SCC. Results indicates a lower sensitivity of rebound value with respect to ultrasonic pulse velocity measurement in case of SCMs implementation. SCC tend to have more reliable results in NDT application.
Improvement of Dry Air Injection System for main cables of Seto- Ohashi Bridges
Authors: Kusuhara Shigeki , Moriyama Akira , Okawa Muneo , Sakamoto Yoshiya
Published: March 2016

A “Dry Air Injection System for main cables (DAIS)” was developed by the Honshu-Shikoku Bridge Expressway Co., Ltd. (HSBE), in order to keep in sound condition of the main cables over the long term. And the DAIS was installed to the Akashi-Kaikyo Bridge as the first case in the world. In parallel with installation of the DAIS in new bridges, the HSBE also installed the DAIS in all the existing HSBE’s suspension bridges, in which progressive corrosion of the cable wires was observed. After approximately ten years of the DAIS installation, the monitoring data in the Seto- Ohashi Bridges showed that Relative Humidity (RH) of inside the cables still remained high in some portions. Through a trial and error process, we made improvements of the DAIS, which mainly composed of alteration of injection points, in order to keep RH of the entire length of the cables less than a target value (40%RH). This paper describes improvements of the DAIS and its results.