Strengthening of Concrete Members Using External Prestressing Fiber Sheet

研究了预应力纤维布加固钢筋混凝土构件的方法。采用碳素片材和芳纶片材作为预应力筋。通过试验评价了预应力纤维布粘贴腹板后混凝土与板材的粘结性能和钢筋混凝土梁的抗弯剪性能。通过实验得出了以下结论：1.从受荷端到固定端的有效长度约为10 cm。剥离剪切破坏的有效粘结区是被斜裂纹包围的直角三角形和横截面侧线的上半部分。粘贴预应力片材后，梁的抗弯强度和抗剪强度均有所提高。有人工裂缝的试件的强度低于无裂缝的试件，而有人工裂缝的试件经预应力板加固后强度提高，达到加固后的无裂缝试件。常规的预应力混凝土理论适用于抗弯强度的预测。将板材与混凝土的粘结强度作为混凝土的抗剪强度，桁架理论适用于预测构件的抗剪强度。

The method for maintenance and strengthening reinforced concrete members using prestressing fiber sheet was investigated. Carbon sheets and aramid sheets were used as prestressing tendon. The bond behavior between concrete and sheet and flexural-shearing behavior of reinforced concrete beam pasted the web with prestressed fiber sheet were evaluated by experiments. Following conclusions were obtained from experiments.1. The effective length from load applying end toward fixed end is about 10cm.2. The effective bond area with peeling-shear failure is the right-angled triangle surrounded by diagonal crack and upper half of the lateral line of the cross section.3. As pasting with prestressing sheet, both flexural strength and shearing strength of beams improved.4. Specimens with artificial cracks showed lower strength compared with specimens without cracks, however, specimens with artificial cracks strengthened by prestressing sheet showed to improve strength up to strengthened specimen without cracks.5. The conventional prestressed concrete theory is applicable for predicting flexural strength.6. The truss theory is applicable for predicting shearing strength of member by regarding bond strength between sheet and concrete as shear strength of concrete.