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Author: Hany Mohamed Seif Eldin Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Structural deficiencies in Railway steel bridges are usually the result of deterioration caused by ageing, corrosion, fatigue, and higher load demands. In this context, steel bridge girders are the structural members prone to corrosion which implies a substantially reduction of their flexural capacities. As a result, a large number of steel railway bridges are in need for strengthening or retrofit. In this thesis, experimental and analytical investigations are conducted to predict the reduction in the flexural capacity of existing deteriorated steel girders under static loading and several retrofitting schemes are developed in the light of strengthening the girder cross-section. The experimental study covers the use of two Carbon Fibre-Reinforced Polymer (CFRP) composite types, namely, normal modulus sheets (NM-CFRP) and high modulus strips (HM-CFRP). A total of thirteen medium-scale W-shape steel beams with a span of 1.6m were tested under four-point bending setup. The thirteen beams were divided in four groups such as: i) Group G1 consisted of four beams with different percentages of cross-sectional area reduction without any strengthening; ii) Group G2 consisted of four notched beams strengthened with bonded NM-CFRP sheets. Herein, two out of the four strengthened beams, were bonded using saturant epoxy, while the other two were strengthened using high performance adhesive; iii) Group G3 consisted of two notched beams strengthened with bonded HM-CFRP strip with and without a wrapping system; iv) Group G4 consisted of three notched beams strengthened with unbonding NM-CFRP sheets and a ductile anchoring system. The results of the experimental study underline the effectiveness of the proposed retrofitting schemes in terms of flexural capacity increase and deflection control of the existing corroded steel girders. In addition to the experimental program, an analytical model was developed to set up a numerical method that is capable of predicting the elastic and post-yield behaviour of the unstrengthened and strengthened deteriorated steel girders. This numerical method can be used by designers to calculate the losses in the moment capacity of the deteriorated steel girders to an acceptable level of accuracy. The analytical model was validated using the experimental results that were presented in the experimental program.
Author: Hany Mohamed Seif Eldin Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Structural deficiencies in Railway steel bridges are usually the result of deterioration caused by ageing, corrosion, fatigue, and higher load demands. In this context, steel bridge girders are the structural members prone to corrosion which implies a substantially reduction of their flexural capacities. As a result, a large number of steel railway bridges are in need for strengthening or retrofit. In this thesis, experimental and analytical investigations are conducted to predict the reduction in the flexural capacity of existing deteriorated steel girders under static loading and several retrofitting schemes are developed in the light of strengthening the girder cross-section. The experimental study covers the use of two Carbon Fibre-Reinforced Polymer (CFRP) composite types, namely, normal modulus sheets (NM-CFRP) and high modulus strips (HM-CFRP). A total of thirteen medium-scale W-shape steel beams with a span of 1.6m were tested under four-point bending setup. The thirteen beams were divided in four groups such as: i) Group G1 consisted of four beams with different percentages of cross-sectional area reduction without any strengthening; ii) Group G2 consisted of four notched beams strengthened with bonded NM-CFRP sheets. Herein, two out of the four strengthened beams, were bonded using saturant epoxy, while the other two were strengthened using high performance adhesive; iii) Group G3 consisted of two notched beams strengthened with bonded HM-CFRP strip with and without a wrapping system; iv) Group G4 consisted of three notched beams strengthened with unbonding NM-CFRP sheets and a ductile anchoring system. The results of the experimental study underline the effectiveness of the proposed retrofitting schemes in terms of flexural capacity increase and deflection control of the existing corroded steel girders. In addition to the experimental program, an analytical model was developed to set up a numerical method that is capable of predicting the elastic and post-yield behaviour of the unstrengthened and strengthened deteriorated steel girders. This numerical method can be used by designers to calculate the losses in the moment capacity of the deteriorated steel girders to an acceptable level of accuracy. The analytical model was validated using the experimental results that were presented in the experimental program.
Author: Xiangdong Liu Publisher: ISBN: Category : Composite materials Languages : en Pages : 340
Book Description
"This dissertation consists of five papers, which presents the results of research on the application of FRP composites on the strengthening steel bridge structures. In particular, the work focuses on both rehabilitation of steel bridge girders (flexural members), and steel bridge columns (compression members) with FRP composite materials. The first paper focuses on the flexural steel member strengthening. Based on the experimental results, it is clear that an increase in stiffness and ultimate load capacity of corroded steel members can be achieved from the application of CFRP laminates to the tension flange of corroded steel members. Peel off of FRP laminates was the observed failure mode of the retrofitted beams. The second through fifth papers investigate the feasibility of retrofitting of compression loaded steel members using FRP composite pipes filled with expansive light-weight concrete. First, a high-expansion light-weight concrete was investigated. Second, the local bond-slip relationship between steel and this type of concrete was developed. Finally, a FRP retrofit method was proposed for corroded steel bridge columns, and deficient steel columns were strengthened using this retrofit technology. Test results indicated that a restoration of ultimate load capacity of a deficient steel column with the proposed FRP retrofit technology is attainable. Also design guidelines were developed for the retrofit of stocky and slender columns"--Abstract, leaf iv.
Author: Ahmed Sabri Abd-El-Meguid Publisher: ISBN: Category : Bridges Languages : en Pages : 215
Book Description
While traditional retrofitting methods for steel bridge girders could be time consuming and uneconomical, an alternative repair method is suggested using Carbon Fiber Reinforced Polymers (CFRP) laminate strips, providing engineers with a competitive solution that will increase the life-cycle of repaired bridges. This study investigated its feasibility as an option to strengthen and rehabilitate steel bridges. The main advantages of using CFRP laminates are their light weight and durability, which results in ease of handling and maintenance. The research conducted experimental and analytical work to evaluate the effectiveness of strengthening steel beams by the use of novel CFRP laminate strips configurations. The research involved the testing of five experimental composite beams, in addition to the development of approximately 100 finite element models. The results showed a significant gain in the beam's elastic and ultimate capacities. The conclusion is that there are specific sensitive parameters controlling the effectiveness of the CFRP laminate rehabilitation technique. An adequate AASHTO design of the rehabilitation method, which takes into consideration the effective parameters, would result in an effective bridge structure.
Author: Vistasp M. Karbhari Publisher: Elsevier ISBN: 0443220832 Category : Technology & Engineering Languages : en Pages : 656
Book Description
Rehabilitation of Metallic Structural Systems Using Fiber-Reinforced Polymer (FRP) Composites, Second Edition provides comprehensive knowledge on the application of FRPs in various types of metallic field structures. Part I provides an overview of the various types of materials and systems and discusses the durability of bonds. Part II focuses on materials-level considerations, such as corrosion and mechanical behavior, putty effects on the effectiveness of pipeline systems, laser joining and the use of carbon and basalt FRP for underwater repair. Building on Part II, the final three sections focus on applications of FRP composites to steel components and various infrastructure systems. This book will be a standard reference for civil engineers, designers, materials scientists, and other professionals who are involved in the rehabilitation of metallic structures using fiber reinforced polymer composites. Contains eighteen new chapters covering materials-level aspects and applications Presents materials developments for tailored bonds, durability, and bond behavior Includes methods of analysis, testing, and implementation across a broad range of sectors Covers design aspects, guidelines, and codes Discusses economic aspects and future prospects
Author: Matthew W. Bolduc Publisher: ISBN: Category : Box girder bridges Languages : en Pages : 256
Book Description
Viable retrofit schemes are necessary to delay or offset replacement of deteriorating concrete bridge members. Carbon fiber reinforced polymer (CFRP) pultruded plates can be especially effective when retrofitting bridge members where stiffness, fatigue resistance, ease of installation, and weathering characteristics are a concern. The research reported in Chapter 1 was undertaken to examine the influence of fatigue loading, prior cracking, and patch materials on flexural performance of reinforced concrete members retrofitted with externally bonded CFRP plates. Moreover, experimental data from the six reinforced concrete beams tested as part of this research are expected to further evaluate available design equations for external retrofitting of reinforced concrete structures. The test results do not suggest a significant effect of fatigue loads; show that existing cracks do not significantly impact the strength of retrofitted members; and indicate that patch materials can reduce the available bond strength, and require additional surface preparation. The research reported in Chapter 2 presents a novel design approach utilizing externally bonded CFRP plates developed in an attempt to overcome construction errors in a member removed from an adjacent box girder bridge. The design methodology was evaluated based on data from testing of a retrofitted girder along with previous tests on as-is girders. Test data suggest appreciable improvements in terms of load carrying capacity and stiffness of the retrofitted girder. The relatively simple retrofit plan developed could have been used to delay replacement of the deficient girders. The research reported in Chapter 3 is aimed at filling some of the gaps in the available test data through retrofitting and testing of a 18.3 m (60 ft) prestressed box girder retrofitted with CFRP composite plates with mechanical anchors. Prior research on the use of CFRPs for retrofitting of existing structures has predominantly focused on mildly reinforced concrete members, and application to prestressed members is rather limited. Moreover, data regarding performance of mechanical anchors for enhancing bond characteristics of CFRP composites are scant. After a description of the design procedure, the test data are used to evaluate the design method, current design recommendations, and performance of mechanical anchors.
Author: Anna Beth Pridmore Publisher: ISBN: Category : Languages : en Pages : 379
Book Description
The deterioration of steel in aging reinforced concrete bridges is a continual problem which could benefit from improved rehabilitation techniques that take advantage of enhanced and more durable materials such as fiber reinforced polymer (FRP) composites. Appropriately designed hybrid material systems benefit from the performance and durability advantages of FRP materials yet remain more cost effective than comparable all-composite systems. Development of rapid rehabilitation systems for the decks of concrete box girder bridges, which are increasingly common throughout the United States, is presented. One goal of this research is to assess and validate the use of FRP composite panels for use as both stay-in-place formwork and as the bottom longitudinal and transverse reinforcement in the deck of concrete box girder bridges. Performance assessments for full-scale two-cell box girder bridge specimens through monotonic and extensive cyclic loading provided validation for the FRP panel system bridge deck as a viable rehabilitation solution for box girder bridge decks. The FRP panel system performed comparably to a conventionally reinforced concrete bridge deck in terms of serviceability, deflection profiles, and system level structural interaction and performed superior to the RC bridge deck in terms of residual deflections, and structural response under cyclic loading. Assessment of a damaged FRP panel bridge deck system, which was repaired using a resin injection technique, showed superior performance for the repaired system in terms of integrity of the FRP panel interface and cyclic response. Rapid rehabilitation techniques for strengthening reinforced concrete box girder bridge deck overhangs using near-surface-mounted (NSM) carbon fiber reinforced polymer (CFRP) were also evaluated. Analytical predictions of load carrying capacity and deflections provided correlation with experimental results, and the developed analysis methods provide an effective design tool for future research. Results from the laboratory testing of a bridge deck overhang strengthened with FRP showed significant increases in load carrying capacity as well as deformation capacity as compared to the as-built specimen without FRP. This research provides enhanced understanding of hybrid structures and indicates significant potential for rehabilitation applications to concrete box girder bridges.
Author: Hany Mohamed Seif Eldin
Author: Hany Mohamed Seif Eldin
Author: Xiangdong Liu
Author: Ahmed Sabri Abd-El-Meguid
Author: Ahmed Sabri Abd-El-Meguid
Author: Trent C. Miller
Author: Vistasp M. Karbhari
Author: Dennis R. Mertz
Author: John W. Gillespie
Author: Matthew W. Bolduc
Author: Anna Beth Pridmore