Reinforced concrete corbels strengthened with external prestressing

Abstract Reinforced concrete structures may demand, throughout their lifetime, the increase of the capacity load due to eventual changes in the load configuration. In this context, corbels could be considered structural elements which present great challenges for installing strengthening solutions. The referred difficulty is due to the fact that the strength capacity of this kind of element is dependent on the strength of a diagonal concrete strut and a tensile steel tie, both located in a very short region also subjected to interferences. In the present paper, the behavior of reinforced concrete corbels strengthened with external prestressing is investigated. For that, nonlinear analysis of short corbels (a/d ratio between 0,5 and 1,0), strengthened or not, have been applied. Also, analytical models based on the Strut-and-Tie Model were developed and the obtained results were compared with experimental results. The obtained results have demonstrated that strengthening reinforced concrete corbels using external prestressing is a fast, efficient and safe solution.

摘要：钢筋混凝土结构在全生命周期中，可能因荷载配置发生偶发变更而需要提升承载能力。在此背景下，牛腿（corbel）可被视为一类给加固方案安装带来极大挑战的结构构件。该类构件的承载能力取决于斜混凝土压杆与受拉钢拉杆的强度，而二者均位于极易受干扰的狭小区域内，这正是前述加固难题的成因。本文针对采用体外预应力加固的钢筋混凝土牛腿的受力性能展开研究。为此，本文对加固与未加固的短牛腿（剪跨比介于0.5与1.0之间）开展了非线性分析。同时，本文基于压杆-拉杆模型（Strut-and-Tie Model）构建了分析模型，并将所得结果与试验结果进行对比。研究结果表明，采用体外预应力加固钢筋混凝土牛腿是一种快速、高效且安全的加固方案。