Effects of environmental conditions at installation phase on bond strength between CFRP and steel.

Abstract

Steel structures such as bridges, off-shore platforms, mining equipment and transmission towers are aging due to external factors and becoming structurally deficient. These deficiencies may be caused by changes in use, increased or fatigue loading of the structure, or by deterioration of the structure itself through the process of corrosion. Retrofitting of structures are economically feasible than replacing by a new structure. Rehabilitation and strengthening of such structures using Carbon Fiber Reinforced Polymer (CFRP) are very popular in the civil engineering industry. However retrofit of steel bridges with CFRP has not yet yield and extensively acceptance technology in Sri Lanka as well as many other countries worldwide there are many applications in strengthening and roofs. bridge girders, steel trusses ... . Rehabilitation and . u-p g- rading of existi.n g ste. e, l .b,r idgesr cha s. become a major issue that often requires immediate attention because most of steel bridges ot bn Lanka build colonial period. However most of research is focused with low humidity environment but Sri Lanka is tropical country as a result humidity level is high. This paper presents the overview of preliminary test programme, test results and the short term behaviour of CFRP strengthened steel plates under different humidity level of environment. In this research paper furthermore review drawbacks of this technology and research gap. In addition to providing a greater guidelines and recommendations on the CFRP composite optimization, reliability, and environmental feasibility, this effort is revealed to implement this high-performance technology in Sn Lanka because ot better durability and cost effectiveness over conventional techniques. This paper focuses on the use of externally bonded Carbon Fiber Reinforced Polymer (CFRP) materials to strengthen steel plates with simple but joint subjected to tension. A fully slender steel section was selected in this test programme (50mm x 4mm). CFRP strengthened steel under various humidity levels and tested to fail under axial tensile load. The middle part of the strut bonded with epoxy and externally strengthened using CFRP sheet. The test results showed a is.gn.ficant strength variation from 1.05kN to 1.28kN due to different relative humidity level from 47/o at 19 C to 90/o at 30°C failure mode of strengthened members. This study conhrms that there is wide range of strengthen vary due to relative humidity level and ambient temperature cure time and the short term performance of CFRP strengthened steel structure under axial tension.