Abstract
M.Ing. (Civil Engineering)
The use of epoxy-bonded steel plate (EBSP) is becoming a well-known solution in the field of civil engineering around the world for strengthening structural elements such as beams, columns and slabs. This thesis presents an experimental study aimed at investigating the flexural behaviour (structural behaviour) of simply supported under-reinforced concrete (URC) beams, strengthened in flexure by externally-bonded steel plates (EBSP) with varying width-to-thickness ratio. This required an experimental investigation, which took place at the material laboratories at the University of Johannesburg (UJ), South Africa.
The experimental program was carried out on 17, 175 x 300 x 3200 mm rectangular reinforced concrete (RC) beams. Two beams were not strengthened with steel plates and they were considered as control specimens, whilst the remaining beams were categorised into three groups with five (5) beams in each group. The first group of beams was externally strengthened with 4 mm steel plates, the second group was externally strengthened with 6 mm steel plates and the third group was externally strengthened with 8 mm steel plates, in flexure. Furthermore, in each group, the width of the bonded steel plate varied from 75 mm to 175 mm, with increments of 25 mm.
All the beams were tested simply supported under two-point static loadings until failure over a clear span of 3000 mm. To achieve the goals of this experimental investigation, the load-deflection response, strain distribution at the mid-span of the bonded steel plate, cracking load, crack patterns and associated failure modes of the tested specimens were recorded. From the experimental results, it is observed that the externally bonded steel plates led to an increase in flexural stiffness, maximum load carrying capacity, cracking load, decrease in vertical deflections and crack-widths as compared to the control beams. Furthermore, there is a limit to width-to-thickness ratio of the steel plate which the premature shear or bond failure occurs without beams achieving their full flexural capacity.