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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 15 Abstracts search results
Document:
SP165-05
Date:
December 1, 1996
Author(s):
Wolfgang O. Eisenhut
Publication:
Symposium Papers
Volume:
165
Abstract:
Repair and strengthening of concrete structures by external reinforcement with steel plates affords the manufacturer of concrete adhesives an attractive new and potentially large opportunity for his products. In this application, bond lines are generally thicker and environmental effects more pronounced than in more traditional uses of such adhesives. In plate bonding, the adhesive becomes an integral part of the reinforcement system and must be capable of transferring stresses without lasting hysteresis effects. High modulus epoxy adhesives with high heat deflection temperatures (HDT) have been shown to have the necessary creep resistance and shear strength. In plate bonding, the internal steel surface is not protected against corrosion by the alkalinity of concrete. Corrosion resistant primers were found either to lack bond strength at high temperature or to enhance a reaction between the freshly prepared metal surface and the hardener component of the epoxy adhesives, which led to the use of unprimed steel plates. Unfilled, low viscosity resins appear to have better barrier properties against corrosion than filled pastes. Treatment of freshly prepared steel surfaces with certain silanes appears to retard flash rust formation as claimed in the literature.
DOI:
10.14359/1392
SP165-07
Brian Hobbs,S, R. Narayan Swamy, and Mark Roberts
Extensive research has established that the provision of epoxy bonded steel plates as external reinforcement can be effective and efficient in enhancing the serviceability and ultimate strength of reinforced concrete beams. This plate bonding technique has many technical and practical advantages and provides an economic means of strengthening and rehabilitating damaged and/or deteriorated structures. There is, however, only limited data on the long term performance and durability of such strengthened beams. This paper presents the results of a comprehensive test program in which 21 steel plated reinforced concrete beams, both unloaded and loaded, were exposed to natural weathering for up to 12 years, without any maintenance, in an industrially polluted area. The main variables investigated include adhesive thickness, number of plates, and number and location of plate laps. The beams were examined in great detail after the exposure period; the extent of corrosion damage and the mechanisms of deterioration due to this exposure are critically evaluated and presented.
10.14359/1393
SP165-11
Emo Agneloni
This paper shows the application of a new technique called the plate bonding technique to repair damaged structures. The good results obtained show the ability of this technique to solve different structural problems and demonstrated its validity and flexibility from a technical and economic point of view. To have good results, it is necessary to begin with knowledge of the causes of deterioration; therefore, this paper deals with the four main groups of testing methods to analyze these deficiencies. Two examples of research and tests analyzing the applied technique are included which confirm its validity.
10.14359/1471
SP165-13
Hamid Saadatmanesh and Mohammed R. Ehsani
The static strength of reinforced concrete (RC) beams strengthened by gluing glass fiber reinforced plastic (GFRP) plates to their tension flanges is experimentally investigated. Five rectangular beams and one T- beam were tested to failure under four-point bending. The measured load versus strain in GFRP plates, steel reinforcing bars, extreme compression fiber of concrete, and the load versus deflection for the section at midspan of the beams are plotted and compared to the predicted values. The results indicate that the flexural strength of RC beams can be significantly increased by gluing GFRP plates to the tension face. In addition, the epoxy- bonded plates improved the cracking behavior of the beams by delaying the formation of visible cracks and reducing crack widths at higher load levels.
10.14359/1473
SP165-14
Hamid Saadatmanesh, Mohammad R. EhsaniI, and Wei An
Analytical models based on the compatibility of deformations and equilibrium of forces are presented to predict the stresses and deformations in concrete beams strengthened with fiber composite plates epoxy-bonded to the tension face of the beams. The models are given for beams having rectangular and T cross sections. A parametric study is conducted to investigate the effects of design variables, such as plate area, plate stiffness and strength, concrete compressive strength, and steel reinforcement ratio. The moment versus curvature diagrams for various combinations of these variables are plotted and compared. The results indicate that bonding composite plate to a concrete beam can increase the stiffness, yield moment, and flexural strength of the beam. The method is particularly effective for beams with a relatively low steel reinforcement ratio.
10.14359/1475
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