European Bridge Conference
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SHEAR STRENGTHENING OF PRESTRESSED CONCRETE BEAMS UNDER CYCLIC LOADING WITH TEXTILE REINFORCED CONCRETE, |
M Herbrand & J Hegger, RWTH Aachen Univ, Germany | |||
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A large part of the existing highway bridges in Germany exhibits calculative shear capacity deficits under static and cyclic loading. More structures are expected to demand refurbishment and strengthening within the next years, especially due to the current conditions of many older road bridges in Europe. Since a reconstruction of the respective bridges is not reasonable or financially feasible in many cases, the assessment and development of effective strengthening methods becomes more important. Many strengthening methods have proven to be suitable for the shear strengthening of bridges, e.g. additional external prestressing, additional concrete layers, additional steel reinforcement in slots or glued CFRP-stripes (Carbon Fibre Reinforced Polymer). However, the applicability and effectiveness of these methods are also influenced by some disadvantages. Besides these common strengthening methods, the use of textile reinforced concrete (TRC) offers an innovative alternative for strengthening measures by combining the advantages of lightweight glued CFRP-stripes and additional concrete layers, which possess better bond characteristics and lower temperature sensitivity. As the textile reinforcement does not require protection against corrosion, thin layers of reinforcement are possible. For the above reasons, two full scale tests on I-shaped prestressed concrete beams (h = 0,7 m, l = 6,5 m) under cyclic shear loading were carried out at the Institute of Structural Concrete at RWTH Aachen University. Previous tests on identical non-strengthened beams served as a reference for the tests on members strengthened with textile reinforced concrete. The paper presents the test results with regard to the effectiveness, advantages and possible fields of application of this innovative strengthening method. |
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1322 |
RETROFITTING OF BRIDGES FOR SEISMIC VULNERABILITY REDUCTION |
SP Stefanidou, Aristotle Univ of Thessaloniki, Greece & Prof AJ Kappos, City University, London, UK | ||
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The key objective of this paper is to quantify the effect of retrofitting a bridge using different retrofit techniques in terms of probabilistic seismic vulnerability curves (fragility curves). To this purpose, an analytical, component-based methodology is developed. The capacity of different bridge components (piers, bearings, abutments), retrofitted using alternative techniques, i.e. reinforced concrete (R/C) and fibre-reinforced polymer (FRP) jackets, and replacement of old bearings with high-damping ones, is analytically estimated, using global engineering demand parameters; hence threshold values are defined for different limit states. A key point is the correlation of global engineering demand parameters (displacement, drift) to local ones (curvature, material strain), taking into consideration different failure modes of the bridge components. The effect of the degree of retrofitting on the performance of bridge components (piers having various geometric properties) is evaluated and closed-form correlation equations are derived for the piers, based on a parametric investigation; aleatory and epistemic uncertainties are quantified using a reduced sampling technique (LHS). Fragility curves are generated for a retrofitted bridge (case study), using a probabilistic seismic demand model based on the results of inelastic dynamic response history analysis for appropriately selected earthquake ground motions, and combining the individual component fragility (series or parallel connection). The results can be further expressed in terms of cost-related parameters and be used to identify the optimum retrofit solution. |
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Post-Tensioned Concrete Bridges |
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1279 |
CABLE IMPREGNATION FOR POST-TENSION GROUTING PROBLEMS |
D Whitmore, D Simpson & H Liao, Vector Corrosion Technologies, Winnipeg, Canada, I Lasa, Florida DoT, Gainsville FL, USA | ||
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Thousands of bridge structures utilize grouted high-strength post-tension strands. Problems with grouting techniques and grout materials has resulted in bridges with deficient grout including voids, chloride contaminated grout and soft grout. These problems have promoted corrosion and failure of post-tension tendons, some within 6 to 17 years of service. The Florida Department of Transportation (FDOT) has spent more than $55 million (USD) repairing 11 post-tension bridges to date. A cost-effective corrosion mitigation technique has been developed to minimize the corrosion of post-tension bridges which have grouting issues. This paper describes the development and implementation of this technique including application to grouted tendons of the Ringling Bridge (Sarasota, FL) and the I-95 / I-295 Interchange in Jacksonville, FL. |
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1266 |
INVESTIGATIONS OF P-T BRIDGES WITH CRITICAL PRESTRESSING STEEL REGARDING HYDROGEN-INDUCED CRACKING (HIC), |
A W Gutsch & M Walther,TU Braunschweig, Germany | ||
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In Germany there are about 120,000 road bridges. Due to consistent increase of traffic loads in the last decade, the bearing capacity of about 2,000 of them has to be carefully checked. In this group, several of the bridges were built between 1960 and 1978. During this period the new construction type of prestressing steel was used in many bridges. Already in the construction phase the first damages on the prestressing steel occurred. Only a few hours after finishing the tensioning of the tendons, single wires failed without advance notice, still before the ducts had been injected with grouting mortar. In other cases wire breakage was detected several years after completion and designated use. The analyses of several cases of damage revealed that the wires and strands had collapsed due to hydrogen-induced stress corrosion cracking (HIC). After a closer look to the observations, single manufactures and batches could be named. Today the prestressing steel used in those days is classified into two groups: the old type of potentially critical prestressing steel produced between 1960 and 1965 and the new type of potentially critical prestressing steel produced between 1965 and 1978. Wires for prestressing steel were mostly produced with an oval, or less often also with a round, cross-section, of 30 mm2 to 40 mm2 surface area. The critical prestressing categories are generally classified to the strength class St 145/160 (new classification St 1420/1570) [1, 2]. |
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1195 |
EFFECT OF FREQUENCY RANGE ON SIBIE FOR IDENTIFYING PARALLEL ARRAY OF PRE-STRESSING DUCTS |
M Kira & M Ohtsu, Kumamoto Univ, Y Masahiko & T Tokumitsu, Fuji P.S Co., Ltd, Tokyo, Japan | ||
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In Germany there are about 120,000 road bridges. Due to consistent increase of traffic loads in the last decade, the bearing capacity of about 2,000 of them has to be carefully checked. In this group, several of the bridges were built between 1960 and 1978. During this period the new construction type of prestressing steel was used in many bridges. Already in the construction phase the first damages on the prestressing steel occurred. Only a few hours after finishing the tensioning of the tendons, single wires failed without advance notice, still before the ducts had been injected with grouting mortar. In other cases wire breakage was detected several years after completion and designated use. The analyses of several cases of damage revealed that the wires and strands had collapsed due to hydrogen-induced stress corrosion cracking (HIC). After a closer look to the observations, single manufactures and batches could be named. Today the prestressing steel used in those days is classified into two groups: the old type of potentially critical prestressing steel produced between 1960 and 1965 and the new type of potentially critical prestressing steel produced between 1965 and 1978. Wires for prestressing steel were mostly produced with an oval, or less often also with a round, cross-section, of 30 mm2 to 40 mm2 surface area. The critical prestressing categories are generally classified to the strength class St 145/160 (new classification St 1420/1570) [1, 2]. |
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1268 |
DIFFERENT WAYS TO INVESTIGATE AND TO REPAIR THE DAMAGES OF A POST-TENSIONED DECK OF A HIGHWAY BRIDGE AFTER A FIRE INCIDENT DUE TO A TRAFFIC ACCIDENT |
Dr AW Gutsch, TU Braunschweig, Germany | ||
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Due to a traffic accident on a highway a truck started to burn just under a post-tensioned reinforced concrete bridge. The rapid development of the fire caused significant damages like concrete spallings of the concrete cover at the underside of the bridge deck. The question was whether the degree of damages was so critical that a repair of the bridge deck was possible or not. In this report the systematic way to investigate the bridge and to classify the damages after the fire incident will be presented. New methods were used to estimate the temperature exposure of the pre-stressing steel during the fire. Only by these methods the decision to repair the bridge was possible. Finally the applied repair concept with different steps, methods and materials will be shown. |
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Joint Details & Bearings |
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1149 |
PERFORMANCE OF PRECAST CONCRETE BEARINGS ON STEEL STRINGERS FOR AN ELEVATED LIGHT RAIL |
J Pearson & R Lindberg, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL, E La Guardia, Michael Baker Corporation, Philadelphia PA, USA | ||
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Reconstruction of the Frankford elevated light rail line, originally constructed beginning in 1915, was completed in 1997. As part of the reconstruction, removal of portions of the existing structure and installation of new structural elements was performed. The original foundation, steel columns and cross girders remained while the deck and its support substructure were replaced. The new rail deck consisted mainly of precast concrete panels. Those portions of the precast concrete deck panels, which bear on and are attached to the supporting structural steel stringers, are referred to as haunches. The intent of certain haunch connection details was to allow the concrete deck panels to be free to move or slip when loaded. In 1998, Southeastern Philadelphia Transit Authority (SEPTA) identified several haunch locations where concrete spalled at the bearings. By 2007, it was found that the number of distressed haunches had grown to over 5,000. An investigation was performed to review existing haunch conditions, investigate the precast concrete haunch distress, identify the cause of distress and recommend repairs. This work consisted of a document review of previous studies, field investigation and testing, laboratory testing, haunch distress inspection, and repair prototype constructability and testing. The investigation, testing, and analysis of data were performed to determine the extent and cause(s) of haunch distress, and determine options for repairing delaminated and spalled haunch concrete. This paper will describe the observed behavior of the haunch connections in the field and the lab in order to understand the causes for the precast concrete spalling. The haunch reinforcement repair to resist the unintentional partial composite action is described. |
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1262 |
BEHAVIOUR OF ECC LINK SLABS FOR JOINT-FREE BRIDGE CONSTRUCTION |
K Hossain, Ryerson Univ, Toronto, ON, Canada | ||
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The expansion joints are a major source of deterioration of multi-span bridges in Canada and North America. Expansion joints can be replaced by flexible link slabs forming a joint-free bridge. The high strain capacity while maintaining low crack widths makes engineered cementitious composite (ECC) an ideal material for the link slab construction. The use of ECC link slab in joint free bridge construction is an emerging technology and very few research has been conducted to date on this novel form of construction. This paper presents the results of an experimental investigation on behaviour of volcanic ash based ECC (VAECC) link slabs under monotonic loading. The performance of VAECC link slab compared to its normal concrete (NC) counterpart is described based on load-deformation response, crack development, and stress-strain characteristics in reinforcement and concrete. |
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Composite Bridges |
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1254 |
USE OF INNOVATIVE “COMPOSITE DOWELS” IN PREFABRICATED COMPOSITE BRIDGES |
J Gallwoszus, J Hegger, M Kopp, M Gundel & M Feldmann, RWTH Aachen, Germany | ||
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Composite dowels are known as powerful shear connectors in steel-concrete-composite girders. More and more they are used in practice especially for prefabricated composite bridges. Advantages over headed studs are in particular the increased strength, the sufficient deformation capacity even in high strength concrete and the simple application in steel sections without upper flange. However, missing provisions in standards for composite dowels with the economic clothoid and puzzle strip have led to retentions of clients and delays in the approval process. Hence, the aim of the recently finished German research project P804 (P804, 2014) founded by FOSTA- Research Association for Steel Application was to solve open questions concerning these innovative shear connectors and to prepare a general technical approval available for any design office and construction company. In this paper design concepts for ultimate limit state and fatigue limit state, structural design principles and instructions for production and construction are presented and background information are given. |
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1174 |
HYBRID COMPOSITE BEAM (HCB) BRIDGE IMPLEMENTATION & FIELD MONITORING, |
MA Abeol Seoud & , JJ Myers, Missouri Univ of Science & Technology, Rolla MO, USA | ||
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This project involves the field evaluation of three Hybrid-Composite Girder Bridges in Missouri, USA. These hybrid composite beams (HCB)s are comprised of three main sub-components: a composite shell, compression reinforcement, and tension reinforcement. The shell is comprised of a fiber reinforced polymer (FRP) box beam. The compression reinforcement consists of self-consolidating concrete (SCC) which is pumped into a profiled conduit within the shell. The tension reinforcement consists of galvanized steel tendons anchored at the compression reinforcement ends. Due to the novelty of the HCB and its unclear behavior, an integrated study is under implementation to evaluate the recently constructed hybrid bridge superstructures. To achieve the goals of this study, a series of load tests was applied to the three bridges and the HCBs deflections were measured. HCB elements have been instrumented with various sensors and the induced strains were recorded at several stages and under the applied test loads. Finite element models (FEM)s were constructed via ANSYS and SAP2000 commercial softwares. Mathematical calculations were performed to predict the deflections and the strains using the existing design methodology. The study showed that the new HCB is a promising technique in the bridge applications. The HCB unique configuration optimizes its performance and leads to lightweight, cost-effective, and durable member. The existing design procedure is simple and suites the bridge designers. However, it needs some refinements. This paper presents briefly the work achieved to date and highlights the concluded remarks. The fabrication and construction sequencing of the HCB is also presented. |
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1264 |
A PEDESTRIAN BRIDGE MADE OF TEXTILE REINFORCED CONCRETE |
S Rempel & J Hegger, RWTH Aachen Univ, C Kulas, Groz-Beckert KG, Solidian, Germany | ||
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The present paper exposes the project and construction of one of the most singular viaducts in Spain which crosses above the existing motorway M-31, with a very acute angle of 20º. Due to the obliquity of the crossing, the solution of the bridge has been made as a skewed bridge (“in pérgola”) with a length of 153 m. |
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Rail Bridge Investigation & Repair |
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1316 |
NEW BRIDGE “IN PÉRGOLA” FOR HIGH SPEED TRAINS TO THE NORTHWEST OF SPAIN |
Dr C Jurado Cabanes, Polytechnic University of Madrid, Spain | ||
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The present paper exposes the project and construction of one of the most singular viaducts in Spain which crosses above the existing motorway M-31, with a very acute angle of 20º. Due to the obliquity of the crossing, the solution of the bridge has been made as a skewed bridge (“in pérgola”) with a length of 153 m.
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Masonry Arch Bridges & Bridge Scour |
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1251 |
MASONRY ARCH STRENGTHENING OF EDEN BRIDGE (LATHRISK) |
P McKenna, D Dunne, CH2M HILL, Glasgow & Worcester, F Ratcliffe, Fife Council, Glenrothes, UK | ||
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Located by Lathrisk in Fife, Scotland, Eden Bridge is a two span masonry arch which dates from the 1800’s. The structure is frequently trafficked and is deemed a Grade B listed structure by Historic Scotland. As a consequence of its age, condition and humped back profile the northern span across the River Eden was subject due to the northern span to a weight restriction of 7.5 Tonnes Gross Vehicle Weight, following previous assessment. This paper will outline the steps taken to enhance the structural capacity by means of a simply supported reinforced concrete relieving slab in line with BA 16. This solution for the northern arch spanned between the north abutment and central pier below springing level, thus relieving the existing arch of all applied loads. In addition to some minor works, an unreinforced slab was also laid over the southern dry (flood) span arch. Collectively these works facilitated an increase in the load carrying capacity to full HA loading and 30 Units of HB. The paper will also demonstrate that the stringent requirements of an historic structure can with due consideration and collective consultation be achieved, whilst remaining sympathetic to the aesthetics of the original structure and realising the goal of increasing the structures functionality. |
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1247 |
UPDATE OF MANUAL ON SCOUR AT BRIDGES & OTHER HYDRAULIC STRUCTURES |
A Kitchen & S Dusting, JBA Consulting, Skipton, AM Kirby & J Chesterton, Mott MacDonald, M Roca & M Escarameia, HR Wallingford, P Charles, CIRIA, London, UK | ||
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Bridges over water can be at risk of failure due to scour and flooding. However, bridge owners and managers face conflicting demands between the need to ensure public safety and commercial pressures to keep bridges open to minimise disruption and avoid penalties. Guidance on scour risk management is currently provided by the Manual on scour at bridges and other hydraulic structures (May et al, 2002). The Manual touches on risk management, with comprehensive advice on scour processes, scour assessment and the design and installation of scour countermeasures. Recent bridge failures have highlighted the importance of the scour risk management cycle, from asset identification and scour assessment to mitigation, inspection and monitoring. Furthermore, recent research has improved our understanding of scour for the purposes of design, mitigation and maintenance. The Manual is therefore being updated with new guidance on scour risk management, including emergency planning, inspection, monitoring, debris management, revised equations for the prediction of scour and updated advice on scour countermeasures. The new Manual, due in 2014, will also provide lessons learnt with case studies such as Lower Ashenbottom viaduct (2004), River Crane, Malahide viaduct and Cumbria (all 2009) and a summary of methods for the assessment of hydrodynamic forces. |
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