1、 1 外文资料 The Tenth East Asia-Pacific Conference on Structural Engineering and Construction August 3-5, 2006, Bangkok, Thailand Structural Rehabilitation of Concrete Bridges with CFRP Composites-Practical Details and Applications Riyad S. ABOUTAHA1, and Nuttawat CHUTARAT2 ABSTRACT: Many old existing b
2、ridges are still active in the various highway transportation networks, carrying heavier and faster trucks, in all kinds of environments. Water, salt, and wind have caused damage to these old bridges, and scarcity of maintenance funds has aggravated their conditions. One attempt to restore the origi
3、nal condition； and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites. There appear to be very limited guides on repair of deteriorated concrete bridges with CFRP composites. In this paper, guidelines for nondestructive evaluation (NDE),
4、 nondestructive testing (NDT), and rehabilitation of deteriorated concrete bridges with CFRP composites are presented. The effect of detailing on ductility and behavior of CFRP strengthened concrete bridges are also discussed and presented. KEYWORDS: Concrete deterioration, corrosion of steel, bridg
5、e rehabilitation, CFRP composites. 1 Introduction There are several destructive external environmental factors that limit the service life of bridges. These factors include but not limited to chemical attacks, corrosion of reinforcing steel bars, carbonation of concrete, and chemical reaction of agg
6、regate. If bridges were not well maintained, these factors may lead to a structural deficiency, which reduces the margin of safety, and may result in structural failure. In order to rehabilitate and/or strengthen deteriorated existing bridges, thorough evaluation should be conducted. The purpose of
7、the evaluation is to assess the actual condition of any existing bridge, and generally to examine the remaining strength and load carry capacity of the bridge. 1 Associate Professor, Syracuse University, U.S.A. 2 Lecturer, Sripatum University, Thailand. 2 One attempt to restore the original conditio
8、n, and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites. In North America, Europe and Japan, CFRP has been extensively investigated and applied. Several design guides have been developed for strengthening of concrete bridges with CFRP
9、composites. However, there appear to be very limited guides on repair of deteriorated concrete bridges with CFRP composites. This paper presents guidelines for repair of deteriorated concrete bridges, along with proper detailing. Evaluation, nondestructive testing, and rehabilitation of deteriorated
10、 concrete bridges with CFRP composites are presented. Successful application of CFRP composites requires good detailing as the forces developed in the CFRP sheets are transferred by bond at the concrete-CFRP interface. The effect of detailing on ductility and behavior of CFRP strengthened concrete b
11、ridges will also be discussed and presented. 2 Deteriorated Concrete Bridges Durability of bridges is of major concern. Increasing number of bridges are experiencing significant amounts of deterioration prior to reaching their design service life. This premature deterioration considered a problem in
12、 terms of the structural integrity and safety of the bridge. In addition, deterioration of a bridge has a considerable magnitude of costs associated with it. In many cases, the root of a deterioration problem is caused by corrosion of steel reinforcement in concrete structures. Concrete normally act
13、s to provide a high degree of protection against corrosion of the embedded reinforcement. However, corrosion will result in those cases that typically experience poor concrete quality, inadequate design or construction, and harsh environmental conditions. If not treated a durability problem, e.g. co
14、rrosion, may turn into a strength problem leading to a structural deficiency, as shown in Figure1. 3 Figure1 Corrosion of the steel bars is leading to a structural deficiency 3 Non-destructive Testing of Deteriorated Concrete Bridge Piers In order to design a successful retrofit system, the conditio
15、n of the existing bridge should be thoroughly evaluated. Evaluation of existing bridge elements or systems involves review of the asbuilt drawings, as well as accurate estimate of the condition of the existing bridge, as shown in Figure2. Depending on the purpose of evaluation, non-destructive tests
16、 may involve estimation of strength, salt contents, corrosion rates, alkalinity in concrete, etc. Figure2 Visible concrete distress marked on an elevation of a concrete bridge pier Although most of the non-destructive tests do not cause any damage to existing bridges, some NDT may cause minor local damage (e.g. drilled holes & coring) that should be repaired right after the NDT. These tests are also referred to as partial destructive tests but fall under non-destructive testing. In order to select the most appropriate non-destructive test for a particular case, the
