预应力碳纤维布加固混凝土梁的试验研究

Improving Strengthening Effect of Externally Bonded Prestressed CFRP Sheets on Existing RC Beams

采用自行研制的碳纤维布预应力张拉机具,对10根混凝土梁受力性能进行了试验研究。对比分析了未加固、非预应力碳纤维布加固、预应力碳纤维布加固、施加不同的预应力水平、不同的附加锚固方式梁的开裂荷载、极限荷载、抗弯刚度等受力性能。试验结果表明:粘贴预应力碳纤维布加固可使梁的承载能力有一定程度提高,可大大提高梁的开裂荷载、抗弯刚度,减小梁的挠度和裂缝宽度,能充分发挥碳纤维布高强度特性;在相同预应力水平下,合适的附加锚固方式,可有效防止碳纤维的剥离破坏,进一步提高梁的承载力;所研制的预应力碳纤维布加固技术可用于实际工程。

Aim. Retrofitting reinforced concrete（RC） structures with externally bonded carbon fiber reinforced polymer（CFRP） sheets is already widespread,particularly in developed countries.By prestressing,a higher utilization of the CFRP material is made possible.In the full paper,we explain in some detail our experimental research and its results and their analysis.In this abstract,we just add some pertinent remarks to listing the two topics of explanation.The first topic is： the experimental work.Its four subtopics are： the design of experiments（subtopic 1.1）,the materials tested（subtopic 1.2）,the loading program and measurements of experimental RC beams（subtopic 1.3） and the design of the forcing apparatus（subtopic 1.4）.In subtopic 1.1,we give a table in the full paper summarizing the design parameters of RC beams tested.In subtopic 1.2,we also give a table in the full paper summarizing the main mechanical properties of CFRP sheets.In subtopic 1.4,we describe our specially designed forcing apparatus that can,we believe,implement the prestressing of CFRP sheets.The second topic is： the experimental results and their analysis.Its four subtopics are： the types of failure（subtopic 2.1）,the analysis of ultimate loads（subtopic 2.2）,the deflections of a number of RC beams（subtopic 2.3） and the strains of a number of externally bonded CFRP sheets（subtopic 2.4）.In topic 2,we give Figs.4,5, and 6 and Tables 3,4 and 5 that summarize our experimental results.In topic 2,our analysis of these experimental results shows preliminarily that：（1） prestressed CFRP sheets are utilized more efficiently than un-prestressed sheets;the prestressed beams have higher flexural cracking load,flexural yielding load,and ultimate load as compared to nonprestressed strengthened beams;the prestressed beams enhance flexural cracking load by 75% to 208.3%,flexural yielding load by 42.9% to 71.4% and flexural ultimate load by 22.2% to 70.2% as compared to control beam;（2） the flexural rigidity is raised such that the deflection is decreased with improvement of prestressed levels;the midpoint deflection of prestressed CFRP sheet beams at the yield load is only 27.3% to 45.4% of the unprestressed beams;（3） the beams using anchorage method can avoid sudden debonding failure;under the same prestressing,the beams using suitable anchorage system can improve serviceability behavior and strength;（4） the forcing apparatus is effective,simple and convenient.