Lap-spliced connections of steel and FRP bars in reinforced flexure concrete structures

Nowadays, the concept of energy saving is achieving more attention in building construction. As a critical element of a building, the balcony creates a discontinuity in envelope insulation and causes massive heat losses. To solve this issue, the adoption of fibre reinforced polymer (FRP) bars with the feature of low thermal conductivity in balcony insulation joints is imperative. This introduces a new lap-spliced connection between FRP bars and steel bars in the adjacent slabs. Yet, the lap-spliced connections are usually used for identical kind of rebars, for example, two steel or two FRP bars. There are scarce studies on the combined connection of a steel bar and a FRP bar. To explore this new topic, the present paper summarizes comprehensive knowledge on the tensile lap-spliced steel and FRP bars in flexure concrete specimens based on the current investigations. First, relating information regarding lap-spliced connections is summarized, for instance, connection methods, lap-spliced lengths specified in several codes. Second, important experiment results including various failure modes of flexure specimens, the distribution of tensile stresses and bond stresses along lap-spliced bars are collected and analysed. Third, different factors affecting the bond strength between lap-spliced bars and concrete are discussed. In the end, the obtained knowledge is briefly concluded.