Extending the Service Life of Bridges Using CFRP Laminates and Continuous Decks

Abstract

Deteriorated deck joints and cracks in girders pose a persistent performance and maintenance problem for our bridges. Using jointless bridge decks reduces direct and indirect costs associated with bridge maintenance and repair. Also, using FRP in girders’ flexure strengthening proved to be effective. In this research, an experimental testing was conducted on five girders to study the effect of CFRP bonded to the tension fibers in flexure and sides in shear. This paper also presents an approach to investigate the behavior of jointless bridge deck systems using a nonlinear finite element analysis for bridges subjected to instantaneous and time-dependent effects. The study covers key parameters such as support configurations, time-dependent effects, link slab stiffness, and debonded length. Analytical results of mode of deformation, strains, and deflections were compared with experimental testing. The study suggested that the use of debonded link slab and CFRP laminates in girder repair can be effective in extending the service life of new or repaired bridges. BACKGROUND Concern about the deterioration of bridges has prompted research efforts to find effective and economical rehabilitation systems. Extensive research has shown that externally bonded CFRP laminates improve both short term [Nanni 1997, Okeil et al. 2001] as well as long term behavior of concrete girders. The technique of externally bonding carbon fiber reinforced polymer (CFRP) laminates to reinforced concrete girders is becoming more established as an alternative to traditional structural rehabilitation methods. CFRP laminates has proven effective for both strengthening and stiffening reinforced concrete (RC) bridge girders. CFRP provide extra tensile resistance and are attached to the bottom surface or wrapped around the stem of RC beams using epoxy adhesives. Bonding FRP reinforcement to the tension face of a concrete flexural member with fibers oriented along the length of the member will provide an increase in flexural strength. Increases in overall flexural strength from 10 to 160% have been documented [Sharif et al. 1994]. Possible failure mechanisms are crushing of the concrete in compression before yielding of the reinforcing steel; yielding of the steel in tension followed by rupture of the FRP laminate; yielding of the steel in tension followed by concrete crushing; shear/tension delamination of the concrete cover (cover delamination); and debonding of the FRP from the concrete substrate Another retrofit alternative using continuous decks was studies. Several methods for the analysis of jointless deck systems were proposed [El-Safty 1994, Gastal 1987]. The loaddeflection response of a jointless bridge deck was investigated [El-Safty 1994] using a finite