International Concrete Abstracts Portal

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International Concrete Abstracts Portal

Showing 1-10 of 13 Abstracts search results

Document: 

SP277-04

Date: 

March 1, 2011

Author(s):

S.T. Wyatt

Publication:

Symposium Papers

Volume:

277

Abstract:

Highway bridges are periodically exposed to fires that can cause severe and extensive damage to critical components. After such an occurrence, bridge owners are immediately faced with several critical questions, including: • Is the structure safe for use by the public? • Does the damaged bridge require load posting? • How has the service-life been affected? • What repair or rehabilitation alternatives are available? To properly answer owner concerns regarding the safety and serviceability of critical infrastructure, a complete evaluation consisting of visual inspection, Non-Destructive Testing (NDT), and laboratory testing is required. The objective of the evaluation is to identify the depth and extent of fire damage as well as any change in the physical or material properties in the steel and concrete. This paper entails a discussion of fire related damage mechanisms to highway structures, NDT methods and technologies available for evaluation of fire-damaged bridge elements and repair alternatives to return bridges to safe operation and restore the intended service life. Three case studies will be discussed to demonstrate application of the inspection and evaluation process presented.

DOI:

10.14359/51682369


Document: 

SP277-05

Date: 

March 1, 2011

Author(s):

J. L. Silfwerbrand

Publication:

Symposium Papers

Volume:

277

Abstract:

During the last decade, the Swedish Road Administration (SRA) has transferred resources from corrective to preventive bridge maintenance. Presently, 10 to 15 percent of the budget is devoted to preventive maintenance whereas corrective maintenance, repair, and reconstruction comprise the remaining 85 to 90 percent. This reallocation has resulted in considerable efficiency gains but further savings are likely to be large. Preventive maintenance aims at measures to maintain the function of the bridge structure. Frequent measures include water washing, cleaning, vegetation removal, crack repair, material refill, and stretching of bridge railings. SRA has defined a series of technical requirements to harmonize the preventive bridge maintenance. Several technical requirements state that a structural element or element part “should be 95 percent clean”. SRA has also developed methods to verify that the technical requirements are fulfilled. However, the scientific basis for the relationship between the technical requirements and the function of the bridge structure is unknown or weak. The verification methods are not always unquestionable. The paper contains a critical review of the technical demands for preventive bridge maintenance in Sweden. Do they adequately promote durability and long-lasting service life? Are the prescribed requirement levels appropriate? Could the technical requirements be replaced by other and better requirements? How do they look like in an international comparison? There is a general belief that performance-specified contracts would be more cost-effective than other contract types. Do the Swedish demands facilitate or obstruct performance-specified contracts for bridge maintenance? The questions are discussed in the paper that also contains a summary of a Swedish pilot study conducted at the Swedish Cement and Concrete Research Institute.

DOI:

10.14359/51682370


Document: 

SP277-01

Date: 

March 1, 2011

Author(s):

R. Cuzzilla, M. Di Ludovico, A. Prota and G. Manfredi

Publication:

Symposium Papers

Volume:

277

Abstract:

The paper deals with a rehabilitation case study on a pre-stressed concrete (PC) bridge (named “Torrente Casale”), located in the south of Italy (on the Salerno-Reggio Calabria highway). The bridge, built in the ’70s, was enlarged in 2001 in order to satisfy the new traffic demand. A seismic assessment of the bridge resulted necessary in order to verify its capacity to sustain both gravity and seismic loads. Both destructive and non-destructive tests have been performed in order to evaluate concrete and steel reinforcement mechanical properties. A theoretical analysis was performed, showing that the bridge piers existing cross section and internal reinforcement were not adequate to satisfy the seismic actions. Thus, two rehabilitation systems were investigated: a) an innovative technique based on the combined use of Fibre Reinforced Polymer laminates (FRP) and Steel Reinforced Polymer spikes (SRP), b) a traditional rehabilitation technique (i.e. RC jacketing). The design assumptions and calculations for the rehabilitation as well as the comparison between the effectiveness of the two investigated strategies are presented and discussed in the paper. The main construction phases of the strengthening technique, executed by following the first outlined strategy are also presented and illustrated.

DOI:

10.14359/51682366


Document: 

SP277-03

Date: 

March 1, 2011

Author(s):

D. Yang, B.D. Merrill, and T.E. Bradberry

Publication:

Symposium Papers

Volume:

277

Abstract:

The Texas Department of Transportation (TxDOT) maintains over 33,000 on-system bridges. A considerable number of these bridges are damaged each year by extreme events or structural deterioration and must be repaired rapidly. Externally bonded carbon fiber reinforced polymer (CFRP) composites provide TxDOT with a viable technique for repairing many damaged concrete bridges. CFRP has been used extensively as structural reinforcement for its exceptional engineering properties, simplicity, flexibility, and rapid placement. TxDOT began using CFRP in 1999 and has repaired more than 30 impact-damaged concrete bridges, resulting in considerable time and money savings. This paper summarizes TxDOT’s experience repairing concrete bridges damaged by impact, fire, corrosion, and alkali-silica reaction (ASR), focusing on damage assessment, determination of reparability, and procedures essential for effectiveness. TxDOT engineers have made a conscious effort to utilize CFRP materials to repair impact-damaged beams. CFRP has been used to supplement prestressed strands to restore flexural capacity, laterally ‘harden’ bottom flanges against damage from re-impacts, and enhance the ductility, shear strength, and integrity of concrete bridge beams. For repeatedly impact damaged beams, CFRP has been used as ‘sacrificial’ reinforcement to protect the primary reinforcement, the prestressed strands, and to increase survivability, thus preserving the structure. Recommendations regarding the effectiveness of such CFRP repairs are presented.

DOI:

10.14359/51682368


Document: 

SP277-08

Date: 

March 1, 2011

Author(s):

A.B. Suma, R.M. Ferraro, B. Metrovich, F. Matta, and A. Nanni

Publication:

Symposium Papers

Volume:

277

Abstract:

Non-destructive evaluation techniques were used to assess the condition of a 40-year old concrete bridge operating in an aggressive marine environment. The bridge’s superstructure includes both reinforced and prestressed concrete one-way slabs, and experienced widening, repairs, and recently strengthening by means of externally bonded carbon fiber reinforced polymer (CFRP) laminates. Phase I of the investigation focused on evaluating deterioration of concrete and steel reinforcement by means of in-situ and laboratory testing. A 24 in. by 24 in. [610 by 610 mm] grid was marked on the bottom surface of the supporting slabs to map indicators of physical damage. Measurement of carbonation, pH, chloride content, corrosion potential, and visual inspection were implemented and rendered as layered maps to identify damaged areas. Phase II includes acoustic emission (AE) monitoring under service loads. AE amplitude, duration, energy and hits were analyzed to identify structural activity associated with damage phenomena, such as concrete cracking, slip between corroded reinforcement and surrounding concrete, and debonding of CFRP laminates. The database acquired from Phase I and Phase II was used for damage assessment. Combined results from the different techniques show promise in determining areas of concern with reduced uncertainty than when using a single measurement technique.

DOI:

10.14359/51682373


Document: 

SP277-09

Date: 

March 1, 2011

Author(s):

Y.J. Kim, R.G. Wight, and M.F. Green

Publication:

Symposium Papers

Volume:

277

Abstract:

This paper presents on-site inspection techniques to examine a damaged prestressed concrete girder bridge. The bridge is 18.3 m [60 ft.] and consists of double-tee beams (DT3000 x 700 ) with a 50 mm [2 in.] topping concrete. To simulate the effect of deterioration for the girder, the leg member is intentionally damaged by cutting 2 prestressing strands. A load test is conducted to evaluate the flexural behavior of the bridge before and after the damage. A site inspection is conducted after 10 months of the load test. The inspection techniques used for this study includes the visual inspection, pull-off test, ultrasonic test, rebound hammer test, core test, and surveying. The bridge exhibits significant cracks and spalling of the concrete in the deck and the legs. Corrosion of the reinforcing steels is observed. The pull-off test shows that the bond strength between the flange of the girder and the topping concrete is adequate. The ultrasonic test exhibits some internal defects of the leg member, including an increased transmission time of the ultrasound. The in-situ concrete strength measured is reasonably close to the specified 28 day concrete strength, based on the rebound hammer test and the core test, with an average error of 2.1%. Permanent downward deflections are not observed, whereas a maximum camber of approximately 35 mm [1.4 in.] is measured by surveying. The inspection techniques reported in this study are reliable and recommended to examine concrete bridge elements.

DOI:

10.14359/51682374


Document: 

SP277-07

Date: 

March 1, 2011

Author(s):

Satrajit Das

Publication:

Symposium Papers

Volume:

277

Abstract:

The historic bridge on Henley Street over the Tennessee River in Knoxville, Tennessee is a six-span, 1,389-foot (423 m) long open spandrel reinforced concrete arch bridge flanked by a 165-foot (50 m) long, three-span approach girder structure at each end. The arch span lengths range from 185 feet (56 m) to 317 feet (97 m) with an average rise-to-span ratio of 0.30. In an effort to accommodate six travel lanes, reduce the number of expansion joints in the deck, and use the existing arch structure in its present condition, a 1,720-foot (524 m) long continuous superstructure unit was designed with expansion joints located only at the abutments; however, analytical studies on the bridge showed that the combined effects of superstructure continuity and increased live load demands led to increased forces at various sections of respective structural components of the bridge. A combination of innovative design techniques were used to mitigate these adverse load effects. The bridge improvements were designed in accordance with the National Historic Preservation Act and the Department of Transportation Act of 1966.

DOI:

10.14359/51682372


Document: 

SP277-06

Date: 

March 1, 2011

Author(s):

S. Davis, C.B. Laaber and K. Soudki

Publication:

Symposium Papers

Volume:

277

Abstract:

Fiber reinforced polymer (FRP) reinforcements have emerged as alternative to traditional materials for reinforcing new structures and the rehabilitation of existing structures. This paper will present the first field application on the use of FRP reinforcement to rehabilitate a historic arch bridge located in Cambridge, Ontario Canada. The bridge, Main Street Bridge, is a two span concrete bowstring arch bridge built in 1931. As part of the rehabilitation, the existing deck and sidewalks were removed and replaced. Glass FRP (GFRP) reinforcement was used in the deck and sidewalks. The new deck was 200 mm thick and was reinforced with16mm diameter GFRP bars spaced at 300 mm o/c (top longitudinal) and 19mm diameter GFRP bars spaced at 150 mm o/c (bottom longitudinal). The transverse reinforcements were 16mm diameter GFRP bars at 300 mm o/c (top and bottom). The floor beams supporting the deck were deficient in shear and as such Carbon FRP (CFRP) U-wraps were installed transversely over the beam regions that were deficient in shear. The design for the GFRP reinforcement in the deck and the CFRP reinforcement for shear strengthening of the floor beams was according to the Canadian Highway Bridge Design Code (CSA S6-06). The rehabilitation work including condition assessment, FRP designs, and installation of the FRP systems are discussed.

DOI:

10.14359/51682371


Document: 

SP277-02

Date: 

March 1, 2011

Author(s):

A. Hmidan, Y.J. Kim, D.K. Yoon, and S. Yazdani

Publication:

Symposium Papers

Volume:

277

Abstract:

This paper presents a unique approach to examine the performance of constructed concrete bridges in cold regions, based on a combined statistical analysis and geographic information system (GIS) method. A total of 3,013 bridges and 1,126 bridge decks selected from the State of North Dakota (one of the coldest regions in the United States) are analyzed. Detailed technical information of the examined bridges is obtained from the National Bridge Inventory (NBI) database constructed between 2006 and 2007. A statistical analysis is conducted to identify the critical sources of bridge deterioration in cold regions, in particular concrete bridges, using the ordinary least-square multiple regression method. The performance of concrete bridges under cold weather is in general satisfactory, while the deck slabs are the critical structural members and may require regular maintenance and repair. The contribution of the year-built and the presence of water are the most critical factors to the bridge deterioration. A case study is presented based on a 29-span bridge consisting of cast-in-place deck slabs supported by prestressed concrete and steel plate girders. Detailed inspection results are reported and adequate maintenance methods are discussed.

DOI:

10.14359/51682367


Document: 

SP277

Date: 

March 1, 2011

Author(s):

Editor: Yail J. Kim / Sponsored by: ACI Committee 345

Publication:

Symposium Papers

Volume:

277

Abstract:

This CD-ROM contains twelve papers that were presented at sessions sponsored by ACI Committee 345 at the ACI Spring 2010 Convention in Chicago, IL. The papers contain information relating to the current technology for concrete bridge repair and maintenance. The papers discussed case studies of damage and corresponding repair, state-of-the-art repair technologies, evaluation and inspection techniques, and maintenance of existing concrete bridges. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-277

DOI:

10.14359/51682324


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