bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Nitrate Input from a Water Reclamation Facility on the Occoquan Reservoir Water Quality
Authors: Cubas Francisco J. , Novak John T. , Godrej Adil N. , Grizzard Thomas J.
Published: May 2013

To manage water quality in the Occoquan Reservoir, Virginia, a water reclamation facility discharges nitrified product water that reduces the release of undesirable substances (e.g., phosphorus, iron, and ammonia) from sediments during periods of hypolimnetic anoxia. Results showed that when the oxidized nitrogen (OxN) concentration input to the reservoir was lower than 5 mg N/L during periods of anoxia following thermal stratification, nitrate was depleted in the upper reaches of the reservoir resulting in the release of ammonia and orthophosphate from the sediments downstream. When the OxN input to the reservoir was operationally increased to a concentration greater than 10 mg‐N/L, orthophosphate release was suppressed. Introducing OxN to the system decreased sediment ammonia release but did not eliminate it. By discharging reclaimed water that contained nitrate levels greater than 10 mg N/L, reservoir water quality was protected and the discharged nitrate was converted to nitrogen gas as it moved downstream.
Optimization of A2O BNR Processes Using ASM and EAWAG Bio‐P Models: Model Performance
Authors: El Shorbagy Walid E. , Radif Nawras N. , Droste Ronald L.
Published: May 2013

This paper presents the performance of an optimization model for a biological nutrient removal (BNR) system using the anaerobic‐anoxic‐oxic (A2O) process. The formulated model simulates removal of organics, nitrogen, and phosphorus using a reduced International Water Association (IWA) Activated Sludge Model #3 (ASM3) model and a Swiss Federal Institute for Environmental Science and Technology (EAWAG) Bio‐P module. Optimal sizing is attained considering capital and operational costs. Process performance is evaluated against the effect of influent conditions, effluent limits, and selected parameters of various optimal solutions with the following results: an increase of influent temperature from 10 °C to 25 °C decreases the annual cost by about 8.5%, an increase of influent flow from 500 to 2500 m3/h triples the annual cost, the A2O BNR system is more sensitive to variations in influent ammonia than phosphorus concentration and the maximum growth rate of autotrophic biomass was the most sensitive kinetic parameter in the optimization model.
Centrifugal separation of liquid carbon dioxide from natural gas
Authors: Batalovic Veselin , Danilovic Dusan , Zivkovic Marija
Published: May 2013

Natural gas is becoming more and more a commodity in the global energy
consumption. New technologies like the conversion from gas to liquid,
contribute to this. But more than 16 % of the currently known global gas
reserves cannot be produced due to severe CO2 and/or H2S contamination: (CO2
> 10% and H2S> 5%). The traditional technology of amine treatment is not able
to economically remove these contaminants. The objective of this article is
to investigate the possibilities of centrifugal separation to resolve the
problem. After analyzing the existing situation, in the centrifugal
separation of natural gas, some innovations in separators design and theory
are suggested. The aim of the presented theoretical considerations is that
the complex theory of separation to adapt to the needs of engineers engaged
on the design, development and operation of these devices.
Determination of kinetic parameters for complex transesterification reaction by standard optimisation methods
Authors: Almagrbi Abdualnaser , Hatami Tahmasb , Glisic Sandra , Orlovic Aleksandar
Published: May 2013

This article presents a methodology for kinetic parameter estimation which is
based on standard optimization methods. The parameter estimation procedure is
applied to the example of modelling of non-catalytic transesterification
reaction, based on laboratory experiments performed under elevated pressure.
The kinetic model employed in this study consists of three consecutive and
parallel reversible reactions of the second order, with six kinetic
constants. The influence of the mass transfer effects was considered as well.
The best results were obtained by Genetic Algorithm method. The application
of this method resulted in kinetic parameters with improved accuracy in
predicting concentrations of important reaction intermediates, i.e.
diglycerides and monoglycerides. Activation energies of kinetic parameters
obtained by the Genetic Algorithm method are in very good agreement with
theoretical values determined by molecular orbital calculations.
Review of technological methods and experimental determination of thermodynamic and transport properties of reagents for carbon dioxide removal from flue gases
Authors: Spasojevic Vuk , Serbanovic Slobodan , Stefanovic Predrag , Kijevcanin Mirjana
Published: May 2013

In this work a review of the currently available methods for carbon dioxide
removal from flue gasses is given. Some of them are commercially available,
while others are still under development. Special attention is given to
detailed description of the methods based on hemi sorption by aqueous
solutions of alkanol amines, which found wide commercial use in industry.
Selection of appropriate absorbent, process equipment, methods, working
parameters, combustion process etc. are some of key points that will be
reviewed within this work in order to present advantages and limitations of
carbon dioxide removal methods. In the experimental section density,
viscosity and refractive index of insufficiently investigated carbon dioxide
removal agents, such as monoisopropanolamine (MIPA), diisopropanolamine
(DIPA), triisopropanolamine (TIPA) and currently widely used dietanolamine
(DEA) are provided. The data obtained are crucial for the equipment design
and process optimization.
A discrete time method to the first variation of fractional order variational functionals
Authors: Pooseh Shakoor , Almeida Ricardo , Torres Delfim
Published: May 2013

The fact that the first variation of a variational functional must vanish along an extremizer is the base of most effective solution schemes to solve problems of the calculus of variations. We generalize the method to variational problems involving fractional order derivatives. First order splines are used as variations, for which fractional derivatives are known. The Grünwald-Letnikov definition of fractional derivative is used, because of its intrinsic discrete nature that leads to straightforward approximations.
The Potential Role of Hyaluronic Acid in Postoperative Radiofrequency Surgery for Chronic Inferior Turbinate Hypertrophy
Authors: Manuele Casale , Giacomo Ciglia , Valeria Frari , Antonino Incammisa , Francesco Mazzola , Peter Baptista , Ranko Mladina , Fabrizio Salvinelli
Published: May 2013

Background

We prospectively evaluated the efficacy of hyaluronic acid (HA) as an adjuvant treatment to hasten the improvement of nasal respiration and to minimize patients’ discomfort in the postoperative radiofrequency volumetric tissue reduction (RFVTR) of inferior turbinates.

Methods

We enrolled 57 patients randomly assigned into two groups, HA (22 patients) and saline group (35 patients), which received isotonic saline nasal irrigation. We used the monopolar device somnoplasty for all patients. Visual analogic scale (VAS) and nasal endoscopy were used to assess the outcomes of the treatments during the 1st month of follow-up.

Results

The mean VAS score of the HA group at the 1st week was significantly lower than the control group (3.36 ± 1.89 versus 6.95 ± 1.52; p < 0.05). The VAS score remained significantly lower in the HA group also at the 2nd week (3.43 ± 1.27 versus 5.75 ± 1.39; p < 0.05), becoming similar to the control group at the 4th week (p = ns). Since the first visit the HA group also showed significantly lower crust score than the saline group (p < 0.05), and there was no crust found in either group at the last visit. The compliance to treatment was similar in both groups.

Conclusion

The results of this prospective study suggest a role of HA as a supportive treatment for faster improvement of nasal respiration, also minimizing patients’ discomfort in postoperative nasal surgery, promoting nasal mucosa healing in postoperative RFVTR for inferior turbinate hypertrophy.
Benign Sinonasal Neoplasms
Authors: Hennessey Patrick T. , Reh Douglas D.
Published: May 2013

Benign sinonasal neoplasms are a heterogeneous group of tumors that present with similar symptoms including nasal obstruction, anosmia, rhinorrhea, and epistaxis. The proper workup and accurate diagnosis is essential for these tumors so that the appropriate treatment plan can be established. In this article of benign sinonasal neoplasms, we discuss their typical clinical presentation, histological and radiographic findings, and treatment options.
Olfactory Disorders
Authors: Gaines Alan
Published: May 2013

Decreased sense of smell can lead to significant impairment of quality of life, including taste disturbance and loss of pleasure from eating with resulting changes in weight, and difficulty in avoiding health risks such as spoiled food or leaking natural gas. Recent epidemiological reports have shown that despite fairly low self-reported prevalence of these disorders in large population studies, when validated smell identification or threshold tests are used they reveal quite a high prevalence of hyposmia and anosmia in certain groups, especially the elderly. Several different pathophysiological processes, such as head trauma, aging, autoimmunity, and toxic exposures, can contribute to smell impairment, with distinct implications concerning prognosis and possible treatment. Otolaryngologists are most likely to see this symptom in patients with chronic rhinosinusitis, and this now appears to be caused more by the mucosal inflammation than by physical airway obstruction.
Strengthening orthotropic steel decks with Fibre Reinforced Polymers
Authors: Klap Kees , Warmerdam Paul , Rietveld Gert-Jan , Romeijn Arie , Sterkman Richard
Published: May 2013

This research aims to develop a new composite deck system for strengthening of orthotropic steel bridge decks. In order to increase the fatigue strength of welded components and static strength of the bridge deck, the deck plate is strengthened with a number of layers of Glass Fiber Reinforced Polymer (GFRP) and a mixture of epoxy resin with fine aggregates. The number of layers and thickness of each layer is optimized after performing several experimental tests. This research indicated that the proposed deck strengthening solution reduces bending stresses of steel deck plate to 15 percent of steel stress without strengthening, which means for the fatigue load models as given in NEN-EN 1991 all stresses are below the cut-off limit ∆σL. The static bending strength capacity and stiffness behavior is also investigated to evaluate the performance of the composite section in negative and positive bending moments.
Load Carrying Capacity and Remaining Life Assessment: Damage Mechanics Approach
Authors: Zhelyazov Todor , Buyle-Bodin François , Dotchev Dimitar
Published: May 2013

Material constitutive laws, defined on the meso-scale, are plugged in a semi-analytical procedure in order to simulate the non-linear global mechanical response under service loading of a reinforced concrete beam strengthened with CFRP. The strain-softening concrete behavior is modeled trough a coupling between elasticity and damage. Keeping track of the damage accumulation enables the accurate evaluation of the level of the stiffness degradation in the structural element throughout the loading history. The remaining load-carrying capacity reserve of the strengthened structure is thus predicted.
Renovation of concrete columns by wrapping basalt fiber sheets
Authors: Thohallsson Eythor , Konradsson Arngrimur
Published: May 2013

Basalt Fibre Reinforced Polymer (BFRP) is a new material in civil engineering and has shown to be a promising material for infrastructure strengthening and also in comparison to carbon fiber, glass fiber and other composites, it has some advantages such as high-temperature resistance, corrosion resistance and low cost.

Test program was carried out at Reykjavik University Structural and Composites Laboratory (SEL), by wrapping of fibre-reinforced composite sheets around concrete columns to test the strength and ductility, with and without wrapping. The results of the experimental tests show that BFRP can give a good lateral confinement pressure to concrete columns. This effectiveness provides a good ductile behaviour and delay's column failure even though the confinement ratio is low. This ability is important, for example, in case of earthquake actions.
Seismic Vulnerability Assessment and Retrofit Design of New York State Thruway Bridges
Authors: Shroff Avanti , Zeng Fei
Published: May 2013

After New York State’s Schoharie Creek Bridge collapse in 1987, a comprehensive bridge safety assurance program was developed to supplement the condition-based evaluation obtained from a traditional bridge inspection program, which would provide a more systematic method of reducing the failure vulnerability of the state’s 17,360 bridges. The intent was to assess and rate the degree of risk that is associated with certain design details and circumstances. As a result of this effort, New York categorized risk factors according to six potential modes of failure: hydraulic, overload, steel details, collision, concrete details, and seismic (earthquakes). This paper summarizes the methodology in performing the seismic vulnerability assessment of 457 routine bridges spanning over or carrying the New York State Thruway and performing Structural Integrity Evaluation (SIE) for the representative structures with deficient and inadequate seismic performance. Response spectrum and pushover methods of analysis were performed for a 500 year and 2500 year return periods. The vulnerability modes for the critical structural elements were identified and recommendations for retrofit were also provided.
Seismic Assessment of New Zealand Bridges in non liquefiable soils during Canterbury earthquake sequence
Authors: Palermo Alessandro , Brando Maria
Published: May 2013

On February 22nd, 2011 a Mw 6.2 Earthquake occurred with an epicentre near the town of Lyttelton, 10 km South of the Christchurch Central Business District (CBD), New Zealand. The majority of damage observed was due to liquefaction and lateral spreading of the river banks. However, examples of significant bridge damage on non-liquefiable sites occurred as well. The overall damage suffered by the bridge stock of the city of Christchurch, has been documented and collected into a Bridge Database herein analysed. In the second part of this paper, we focus on the seismic performance of the three key concrete bridges not subjected to liquefaction: Port Hills and Horotane Overbridges, and Moorhouse Overpass. Detailed inspections, supported by numerical analyses, were carried out. The results are consistent with the damage observations and highlight unexpected design issues, such effects of vertical accelerations, slope failure stability, shear-flexure interaction.
Development and Evaluation of Self-Consolidated High Strength Lightweight Steel Fiber Concrete in UAE
Authors: Yenta Sherif , AlHamaydeh Mohammad , Alhajri Rashid , Abdelsalam Aly
Published: May 2013

In this paper, development of self-consolidated high strength lightweight steel fiber concrete (SCHSLWSFC) with local materials in the United Arab Emirates is discussed. The experimental investigation consisted of two phases. Phase I dealt with the development to achieve workability, density, and strength targets with different steel fiber percentages. Evaluation of the mechanical properties was conducted in Phase II. Results from both phases showed that volumetric steel fiber percentages up to 0.65% could be used to achieve a SCHSLWSFC mix which has a 28-day compressive strength of 53 MPa (7600 psi) and density of 1950 kg/m³ (121 lb/ft³). Results of the experimental investigation will be presented and discussed.
Evaluation of Concrete Properties for High Strength Steel Applications
Authors: Yehia Sherif , AlHamaydeh Mohammad , Abed Farid , Rabie Mohamad , Resheidat Saja , El-Kalie Shahinaz , Abudagga Majd
Published: May 2013

Utilizing High-Strength Steel Rebars (HSR) as reinforcement in concrete structures has widely increased recently. However, the American Concrete Institute (ACI) in the ACI-318-11 building code requirements for structural concrete specifies the yield strength to be the stress corresponding to a strain of 0.35%, if rebars with yield stresses higher than 420MPa to be used. This limit is to ensure ductile behavior and avoid concrete crushing as a controlling failure mode. Due to the brittle nature and very high strength of most commercially available high-strength steel rebars there is an inherent difficulty in achieving the steel’s strength through yielding without the concrete crushing and causing a catastrophic brittle failure. The possible problems that could arise from the use of HSR with its limited ductility are: less frequent yet deeper cracks in the concrete matrix, issues with the bond between steel and concrete, and pre-mature or undetected failure in the tensile planes within the member. In addition, a recent study concluded that for serviceability and cracking control, stresses in steel should be limited to 50% of the yield strength to have similar performance of Grade 60 steel. In this paper, extensive evaluation of concrete mixes with different compressive strengths with and without steel fiber will be presented as solutions to such challenges. Also to emphasis the expected benefits of adding steel fiber to improve post cracking behavior, test results will be discussed and presented.
Quick Scan on Shear in Existing Slab Type Viaducts
Authors: Vergoossen Rob , Naaktgeboren Marius , Hart Marcel 'T , de Boer Ane , van Vugt Evert
Published: May 2013

Due to the large number of slab type bridges and viaducts that have to be assessed on shear resistance, a Quick Scan is developed by the Dutch Ministry of Infrastructure and the Environment in cooperation with TNO Research, Delft University of Technology and Royal HaskoningDHV. This Quick Scan is based on a continuous girder as the structural model. For concentrated loads an effective width based on laboratory experiments is taken into account. For skew slabs a factor is implemented in the Quick Scan which is determined by a parametric (quasi) linear elastic analysis with plate/shell elements.

The developed Quick Scan is linked to a database which contains the geometrical, reinforcement and material data of the structures. With the database acting as an input and output container the Quick Scan can be quickly executed on the complete set of hundreds of slab structures. With this automated Quick Scan re-examination the ‘engineer-effect’ is reduced.

The Quick Scan has to give more conservative results than extensive refined linear static (plate/ shell) analyses with finite element models. On the other hand, the Quick Scan has to be fast and easy to use. For this reason it is based on a simple Excel tool. Furthermore, it has to be as accurate as possible, otherwise a large number of slab structures would have to be strengthened or replaced.
New Technique to Temporarily Support Existing Bridges Crossing Water Ways
Authors: Abdullah Medhat
Published: May 2013

A new technique to temporarily support existing bridges to transport abnormal heavy loads using water-structure interaction is presented. The concept, details and applications of this technique are presented. The method was verified experimentally by a real loading test on an existing bridge. The deflections and strains at different control point are negligible. As a result, and after being approved by the Egyptian general authority of roads, bridges and land transportation (GARBLT), this technique was applied to temporarily support many old bridges crossing waterways during the transport of abnormal loads.
The Design of the Refurbishment of the M8 White Cart Viaduct, Glasgow
Authors: Hackney Mike , Gair Cameron
Published: May 2013

The M8 White Cart Viaduct was designed and constructed in accordance with the Department of Transport (DOT) and British Standards of the time and was opened to traffic in March 1968. It is one of the most important major bridges in Scotland, carrying more than 90,000 vehicles a day. However, following an unfavourable assessment of the bridge in 2001, the Scottish Executive Development Department (SEDD now Transport Scotland (TS)) engaged Scott Wilson Scotland Limited (since acquired by URS) to develop a phased refurbishment strategy to upgrade the bridge. The refurbishment proposals included the replacement of the parapets, replacement of the expansion joints, waterproofing, resurfacing, and strengthening of the steel box girders. This paper describes the design of the refurbishment works, particularly the steel box girder strengthening including the replacement of the vulnerable half-joints.
Structural assessment of an existing concrete cantilever bridge: The Hartel bridge
Authors: Slingerland Joost , Hagenaars Peter
Published: May 2013

In this paper the assessment of the cantilever part of the Hartel bridge is presented based on the guidelines given in Eurocode together with Dutch additions and modifications. This assessment takes into account the fact that structural assessment of an existing structure differs from a new structure. Attention is paid to the safety levels, traffic load, archival research and inspection of the bridge condition as well as the applied structural models and calculations. The outcome of the assessment reflects that the safety against shear failure is not sufficient, therefore it is advised to strengthen the bridge by external prestressing inside the box girder. Key points and challenges of applicable measures are discussed.
Assessing and Rehabilitating the Anthony Wayne Suspension Bridge
Authors: Beasley Bob , Coblentz Paul , Eshenaur Scott
Published: May 2013

The Anthony Wayne Suspension Bridge Assessment & Rehabilitation project is located on U.S. Route 2 in Toledo, Ohio. Built in 1931, the bridge is in need of rehabilitation and repair to extend ist life. An inspection and analysis of the suspension spans, deck truss and girder approach were performed prior to rehabilitation design to determine appropriate repair measures. The rehabilitation and repair measures include: concrete deck replacement; cable opening and inspection, structural steel repairs; deck truss span replacement; and deck joint elimination.
Strengthening fly-over Rottepolder junction with external post-tensioning
Authors: Galjaard Hans (J C. ). , Quansah Andrew
Published: May 2013

The fly-over at the highway crossing Rottepolderplein in the A9 consists of two parallel viaducts. Each of them was designed for 3 driving lanes, but both have been used for 2 lanes only since its construction in the late 1970’s. Due to increasing traffic an additional third and (during maintenance of the bridge for the other driving direction) a fourth lane was required. The deck slab was wide enough and reassessment showed that the deck slab, as well as the box-girders had sufficient bending capacity for the intended use. The shear capacity of the box-girders however was insufficient for an additional lane. This was primarily due to changes in the principles with respect to the detailing of the shear reinforcement since the construction. External post-tensioning has been applied to reduce the shear forces in the webs of the box-girders enabling a third, and if necessary fourth, lane.
Renovation design of the Bridge at Ewijk in The Netherlands
Authors: Flint Martin , Vonk Edo , Nagtegaal Gerland
Published: May 2013

The 1055m long cable stayed steel bridge at Ewijk was built in 1976. It requires renovation to provide a solution for fatigue damage in the deck through application of a high strength concrete overlay. The clearance for navigation traffic is also to be increased and a porous asphalt overlay will be applied.

This paper elaborates on the assessment and strengthening design of the steel box girder, which sees a 50% increase in dead load due to the applied overlays as well as increased live loading. An effective strengthening concept was found by stiffening of panels and adding two lines of vertical bracing in the box girder. Both activate more of the existing steel in the box girder, and the bracing provides a new shear path. Increased navigation clearance is obtained by jacking the bridge over its nine pier supports, so that a 1250mm raise in midspan is achieved gradually.
Upgrade of Concrete Bridges by Adaptive Prestressing
Authors: Schnellenbach-Held Martina , Fakhouri Abdalla , Steiner Daniel , Kühn Oliver
Published: May 2013

The constantly increasing traffic intensity on bridges and their ageing process represent new challenges in the field of bridge engineering. An innovative method to retrofit concrete bridges to meet these and further future challenges is the utilisation of an adaptive prestressing of tendons depending on the amount of acting loads. In this paper, the functionality of an adaptive prestressing control system is demonstrated by means of two prototypes, a prestressed aluminium truss and an externally prestressed reinforced concrete T-beam. Through the application of the control system on the prototypes, the deflections could be effectively decreased and critical stress situations in the cross section avoided. The experiments confirmed the potential of the use of adaptive prestressing in concrete bridge constructions.
Single gap expansion joints – an optimal solution for small deck movements
Authors: Spuler Thomas , Moor Gianni , O'Suilleabhain Colm
Published: May 2013

Small movement expansion joints are probably the most important type for most road and bridge authorities due to the dominance of short span bridges in their area of responsibility. Considering the key issues of durability and reliability, robust single gap joints have a great deal to offer and should always be considered for use. Variations on the standard, most commonly used version are available to satisfy specific demands – for example, to minimise installation time and disruption to traffic when installed as a replacement for an old joint. They can also be equipped with surface plates if desired to reduce noise and vibrations under traffic. The factors which should be considered in selecting such an expansion joint for use are presented, along with some well-proven solutions. Armed with this knowledge, bridge owners and engineers will be better able to make informed decisions when selecting and using small movement joints in their structures.
Translations in bridge bearings due to traffic and temperature loads based on a finite element analysis and measurements
Authors: Kostense Niels , de Boer Martijn , Kuilboer Cor P. M. , Leendertz Johan S.
Published: May 2013

This study examines translations (or slide paths) of sliding elements in bridge bearings that occur in practice, due to traffic and temperature loads. A finite element model is made of a concrete box girder bridge and results near the supports are analysed. In addition to the finite element model, measurements are carried out on the bridge itself. During the period of one year the bridge is monitored with respect to the translations and rotations of the bearings, temperature of the bridge and stresses at midspan.
Bridge Management System for UAE: Database Development for Bridge Inventory
Authors: Abdelfatah Akmal , Shanableh Tamer , Yehia Sherif , Saved Ahmed El
Published: May 2013

The size and complexity of managing bridges infrastructure created a movement to develop and use country-specific Bridge Management Systems (BMS) in many countries around the world. Therefore, two of the authors have contributed to the development of a framework for a bridge management system in the United Arab Emirates. The proposed BMS consists of eight main modules, which include inventory, inspection, condition assessment, deterioration models, repair strategy, maintenance, research and development, and decision-making. Each module has inputs, outputs, and inter-relationship with other modules.

In this paper, inventory and inspection modules of the proposed BMS framework were discussed. In addition, the Entity-Relationship (E-R) information modelling technique that is used to create the conceptual information model for the inventory database were presented and discussed.
The Great Belt Link: Establishment of lifetime models
Authors: Gjerding Svend
Published: May 2013

The 18 km long fixed link crossing the Great Belt comprises two bridges and a tunnel: a 6.8 km suspension bridge, a 6.6 km combined road- and railway bridge and an 8 km long bored (twin) tunnel. The Great Belt Link was designed for a service life of 100 years, and to ensure this, an investigation has been carried out to establish lifetime models for the primary concrete structures. Existing reports from routine, principal and special inspections were analysed. Special focus on moist conditions, chloride ingress, air void structure, crack extent and chloride initiated reinforcement corrosion were some of the deterioration mechanisms used in determining the life time service. Primary and secondary deterioration mechanisms were identified, critical areas defined and future operation and maintenance plans for securing a technical and economical operation were drawn up. Recent results from special inspection with particular focus on corrosion in cracks, establishment of cathodic protection systems, potential frost related damages and surface treatment of critical areas are presented in the paper. Cores taken from the critical areas further indicate that special attention should be concentrated at areas with cracked concrete. The results of these investigations clearly indicate that the critical areas apparently only include areas in and around the splash zone and other distinct potential critical areas. This paper will outline some of the investigations used in establishing a lifetime model.
Korean Guideline for Performance-based Assessment of Existing Bridges
Authors: Shin Soobong , Paik Inyeol , Ahn Sang-Sup , Kim Chul-Young , Kim Ho-Kyung , Kim Nam-Sik
Published: May 2013

A series of researches for the assessment of existing infrastructures have been intensively carried out for more than 10 years in Korea. The products will be eventually related to a new guideline or code. Some of them are the results obtained from a joint work between Korean Concrete Institute (KCI) and Japan Concrete Institute (JCI). The results have been contributed to ISO standards of ISO/FDIS 16311-2. KCI implemented the concept into a revised ‘Design Code for Concrete Structures’ published in 2012 and JCI also developed a new 'Guideline for Performance-based Evaluation of Existing Concrete Structures' in 2012. In addition, Korea Expressway Co., as a governmental organization to plan for design and maintenance of highway bridges, is developing a performance-based guideline for the safety assessment of highway bridges. The paper summarizes such activities and research outcomes together with the fundamental approach to the assessment of bridges in Korea. The proposed approach is examined through a field application to an existing highway bridge.
Vision Systems for Analysis of Congested Traffic
Authors: Caprani Colin , Obrien Eugene , Blacoe Serena
Published: May 2013

For long-span bridges, congested traffic forms the governing traffic load condition. This paper reviews the current state of the art and the deficiencies in the data upon which the modelling of congestion is typically based. It is proposed that a vision system be adopted to collect statistical information for the parameters required to properly calibrate congestion models. Conventional methods for the detection of vehicle features in images are described, applied to sample images, and criticised. It is concluded that vision-based methods are a viable tool for gathering inter-vehicle gap data, but that existing methods of wheel detection are not sufficient. Therefore the development of a new technique for wheel detection is recommended and some suitable attributes identified.
Vibration mitigation of railway bridges using adaptive damping control
Authors: Andersson Andreas , Karoumi Raid , O'Connor Alan
Published: May 2013

In this paper, the advantage of an adaptive damping system is presented. A damper with variable stiffness is tuned based on estimates of the real-time frequency response, facilitating optimal vibration mitigation. The performance of the developed routines is investigated on an existing tied arch railway bridge. Based on previous field measurements, resonant behaviour of several hangers was found. In combination with low structural damping, the induced stresses resulted in a reduced fatigue service life. Passive dampers are currently installed on the longer hangers, each tuned to the fundamental natural frequency of the individual hanger. However, increased axial force during train passage results in a significant variation in natural frequency, with an apparent risk of detuning the passive dampers. The predicted performance of an adaptive damping system to account for this variation in dynamic behaviour is presented and its potential application is discussed.
Extending the fatigue service life of a railway bridge by local approaches
Authors: Andersson Andreas , Leander John , Karoumi Raid
Published: May 2013

In this paper, fatigue assessment of a steel railway bridge is presented. The bridge is located in central Stockholm, Sweden, and is one of the most vital links for the railway network. The bridge services both freight trains and commuter trains with more than 500 passages per day. The main load bearing structure is designed as a steel grillage of welded I-beams. Fatigue critical sections have been identified at locations where secondary bracing systems are welded to the flanges of the I-beams. Both numerical simulations and extensive field measurements have shown a significant exceedance of the theoretical fatigue service life. Based on the analysis of local stress concentrations, improvement of fatigue critical details has been suggested. The decrease in stress concentration is demonstrated both by numerical simulations and in-situ field measurements and shows a significant improvement when estimating the remaining fatigue service life.
Fatigue Evaluation and Retrofit of Pearl River Bridge
Authors: McGormley Jonathan , Lindenberg Richard , Santosuosso Brian , Altobelli Nick
Published: May 2013

MDOT commissioned a comprehensive assessment of the I-20/55 Pearl River Bridge in response to cracking in the river crossing spans. Five diaphragm connections were instrumented to evaluate the connection performance under control truck loading before and after the installation of trial retrofits. These retrofits included large cored holes to remove cracks and alter the stresses in the web gap as well as new fillet welds fixing the connection plate to the girder top flange.

Test results show that the cracking is caused by out-of-plane distortion of diaphragm connection plates at the girder webs. Attaching the connection plates by welding to the girder top flange and down 305 mm (12 in.) on the web is the recommended retrofit to address both positive and negative moment region cracking and extend the service life of the bridge by more than 30 years.
Development of self-repairing concrete structures by means of porous network
Authors: Sangadji Senot , Schlangen Erik
Published: May 2013

Concrete, the most widely used man-made construction material, has inherent brittleness. Micro- cracks may occur due to restraint shrinkage deformations and macro-cracks when a concrete element is loaded in tension or bending. This unavoidable crack formation has been the major consideration for water retaining structures. Furthermore they form an issue for realizing a water tight connection between slab and wall of underground structures. Long term durability for reinforced concrete and prevention of reinforcement corrosion due to ingress of (chloride) ions is another field where cracks have an enormous influence. A novel self-healing / self-repairing method has been developed by introducing porous network concrete. Mimicking bone, prefabricated porous concrete was placed internally in the concrete structures. As the fracture might happen, a commercially available low viscosity polymer based resin was used as healing agent which was transported through the porous network by automatic injection. After polymerization reaction took place a dense layer was formed closing the cracks. The efficiency of crack healing was examined by mechanical recovery of cracked specimens and visual confirmation. Having porous network in the concrete interior, several self-healing / self-repairing scenarios could be performed.
Comments on Ductility of Concrete Encased Composite Columns
Authors: Popa Anca Gabriela , Campian Cristina Mihaela
Published: May 2013

The paper describes experimental aspects for composite steel-concrete columns, with steel encased profile. Eurocode 4 provides a relative simple method to design composite columns, but it has some restrictions related to cross section; it applies only for bi-symmetric form of the cross section of the steel shape, and for the concrete class, restricted to maximum C50/60. The main of this work is to analyse the behaviour of composite columns having the concrete of a higher class.
Non-Destructive Techniques for Bridge Inspection in United Arab Emirates
Authors: Yehia Sherif , Qaddoumi Nasser , Hamzeh Layane , Farrag Sharef
Published: May 2013

This paper presents an investigation of the combined defect detectability of Ground Penetrating Radar (GPR) and Infrared Thermography (IRT) in concrete bridges taking into considerations variations in concrete mix proportioning. This variation will exist due to the difference in mix ingredients, aggregate gradations, w/c ratio, and aggregate type. Therefore, four concrete mixes; high strength, normal strength, lightweight and self-consolidated concrete are used in the investigation. The goal is to evaluate the effect of concrete mix variation on the signals and images of the GPR and IRT techniques. Sixteen 1.2m x 1.2m x0.2m slabs with common bridge defects, cracks, voids, delaminations, honeycombing, and corrosion were prepared. Parameters included in the investigation are concrete type, defects type, size, and location. Furthermore, effects of the environmental conditions on the images, such as temperature changes, solar radiation at different times of the day, and will also be assessed. Results and findings will be discussed and presented.
Maintenance strategy assessment on structures – integrating policy, risks and functionality
Authors: Reinders Jos , Reusen Maurice
Published: May 2013

Asset owners of civil structures are wrestling with several issues, such as upcoming high replacement costs, trajectory programming, degree of compliancy to laws and regulations and organizational objectives. In order to support the asset owners with these issues, a multi-criteria analysis on a strategic level is developed. The multi-criteria assessment is based on a qualitative questionnaire. Considering scenarios on net present value of technical and social costs also helps in the decision making.

A new system is introduced with its associated goals, history and developments and deployment options.
Repair and Strengthening of an orthotropic slab with UHPFRC wearing course Bridge at Illzach in France : first return from experience
Authors: Champenoy Damien , Généreux Grégory , Hajar Ziad , Luangkhot Emilie , Moussard Michel , Prybyla Davy
Published: May 2013

Built in 1970, this bridge located in Illzach in the East of France crosses Huningue Canal between Mulhouse and Rixheim. It comprises a single 106 m span carrying a two lanes motorway, with two lateral steel trusses and an orthotropic slab with transverse floor beams.

After the detection in 2009 of numerous cracks in the deck welds, a repair solution, based upon the replacement of the bituminous wearing course by a UHPFRC layer, with local connection to the orthotropic slab, was ultimately adopted. This solution had been thoroughly analyzed and tested in a research program, Orthoplus, on orthotropic slab fatigue issues. The works were performed during the summer of 2011, and the bridge was successfully tested and commissioned afterwards.

This paper presents the design, planning, implementation and monitoring of this innovative repair, after more than one year of operation and associated follow-up investigations.
Monitoring fatigue effects in an orthotropic steel bridge deck
Authors: Tecchio Giovanni , Dona' Marco , Casarin Filippo , Islami Kleidi , Zanini Mariano Angelo , Pellegrino Carlo , Modena Claudio
Published: May 2013

The effect of fatigue is particularly relevant in steel bridges since the influence of traffic load cycles on serviceability limit stress values is very high if compared to relatively low dead weights.

Orthotropic steel decks, directly subjected to traffic loads, are very sensitive to fatigue: in most cases, fatigue defects appear as cracks in the top plates, longitudinal ribs and the bracing of the deck. In this paper the case study of a 20 years old box girder bridge affected by fatigue problems is presented: the bridge has an orthotropic steel deck with three spans whose total length is 152m. The bridge is located in one of the busiest Italian highways, the “Milan-Venice” A4 highway, characterized by high volumes of heavy truck loads. After the cracks appeared on the longitudinal welding of the ribs, a dynamic identification campaign was carried out using piezoelectric accelerometers, and a monitoring system was then installed by positioning 54 strain-gauges along one of the steel decks of the bridge.

The results of the monitoring campaign are here presented, underlining the deficiencies of the original design, and a retrofit interventions are proposed for the bridge deck.
Study on repair of corrosion on upper surfaces of orthotropic steel decks by one-side bonding of steel plates
Authors: Aoki Yasumoto , Ishikawa Toshiyuki , Banno Ryota , Kawano Hirotaka , Adachi Yukio
Published: May 2013

Recently, corrosion damages on upper surfaces of orthotropic steel deck plates are often found during the bridge pavement repair work in urban expressways. Repair methods for these damages are required to be finished quickly, for example within one or two hours, during the pavement repair work. In addition, decrease of thickness or pitting corrosion will lead to stress increase and the acceleration of fatigue damage.

In this study, the authors focused on the repair method of bonding steel patch plates from the upper surface side. In order to investigate the basic mechanical behaviour, finite element analysis and bending tests of thickness-reduced plates repaired with bonding steel plate under bending were carried out. Simple equations for designing the thickness and length of patch plate repair were proposed.
Design checks and nonlinear response of a full 3D model of a box girder bridge
Authors: Frissen Chantal , de Boer Ane , Schreppers Gerd-Jan
Published: May 2013

This paper presents a new approach for design and re-examination of a box girder bridge using a validated 3 dimensional finite element model. The Ministry of Infrastructure and the Environment in the Netherlands wants to quantify the remaining capacity of bridges as present traffic loads of bridges is higher than the loads for which bridges have been designed. Design checks are performed on a full 3-dimensional solid model and the same model is used to predict crack initiation, crack- development and yielding of steel reinforcements.

The analyses result in a prediction and quantification of the required amount of reinforcement, crack pattern, crack opening and plastic deformation of reinforcement, in addition to the traditional output of deformations, stresses and strains. The full 3D modelling approach makes it possible to predict the effect of refurbishing actions for repair and strengthening the bridge accurately. All the analyses are done using the finite element program DIANA version 9.4.4[1].
Monitoring of Reinforcement Corrosion in Field Exposed Concrete Blocks
Authors: Sørensen Henrik Erndahl , Jönsson Ulf , Mathiesen Dorthe , Munch-Petersen Christian
Published: May 2013

Three concrete blocks instrumented with rebars, anode ladders and other sensors have been produced and exposed to sea water in Fehmarn Belt field exposure site in Roedbyhavn in Denmark. The corrosion activity on the anode ladders is continuously monitored by measurements of half-cell potentials and linear polarisation resistance. The design of the instrumented concrete blocks is presented together with the first results after 2 years marine exposure. Corrosion initiation on anodes with small concrete cover has been identified from the electrochemical measurements and verified by visual inspection. Chloride profiles have been measured for three different binders.
Impact of corrosion on the first immersed concrete tunnel, the Maastunnel
Authors: Kees Blom C. B. M.
Published: May 2013

The structure of the first immersed concrete tunnel, the Maastunnel in Rotterdam is more than 75 years old and has always been serving well. Recently the tunnel was upgraded to fulfil the increased traffic and fire safety requirements for tunnels. During those construction activities heavy corrosion of structural reinforcement has been observed.

This paper explains the damage that has been observed, the effects on the structural safety, the urgency and impact of the measures to be taken and the plan to refurbish in order to upgrade the tunnel for 50 more years.

This project actually shows the consequences when the technical lifetime of a major concrete structure in a main city has been exceeded. Since this is the first immersed concrete tunnel it shows what can be expected in the coming decades worldwide.
Experimental Investigations on Upgrading Structures with High Strength Concrete Overlay
Authors: Randl Norbert , Simon Csaba
Published: May 2013

In the frame of the research project “HiPerComp” funded by the Austrian Research Foundation (FFG) several tests were performed in order to investigate the bond properties between normal concrete substrates (about C50/60) and high strength concrete (HSC) overlays with a 28 days compressive cube strength of about 120 MPa. Slant shear tests with different joint angles and bending tests with reinforced concrete slabs were carried out. The substrates were treated with high pressure water jetting and sand blasting to increase the surface roughness.

The usage of HSC overlays leads to a more durable and compact top layer due to its decreased porosity and its resistance is higher against mechanical abrasion, while the bond properties are better compared to normal concrete overlays.
Assessment methods to avoid brittle failure of old steel structures
Authors: Sieber Lars , Stroetmann Richard
Published: May 2013

Although many structures made of mild steel erected during the period between 1890 and 1940 are still in service after decades, there is usually no need to replace them. When assessing these existing steel structures to be able to decide on necessary rehabilitation and reinforcement measures engineers require information about the mechanical as well as the technological properties of the material. Additionally, it is essential to quantify the level of reliability against brittle failure. In contrast to conventional tests such as the impact test, fracture mechanics is suitable for appropriate assessment against brittle fracture of riveted or bolted structures made of old mild steel.