【作者】 李贵炳；

【导师】 金伟良； 张爱晖；

【作者基本信息】 浙江大学 ， 结构工程， 2006， 博士

【摘要】 过去二十几年的试验研究、理论分析及工程实践表明：纤维片(板)材替代钢板加固钢筋混凝土结构的受弯构件是一种十分有效的方法，并且在试验研究和工程应用方面都取得了很多研究成果。但作为一门新兴的结构加固技术，无论在基础研究还是工程应用等方面还有许多亟待解决的问题。例如，不同预载下加固构件与完好状态下加固构件的抗弯性能是否存在差异；加固后构件的变形计算；FRP片材产生剥离破坏的机理及剥离承载力的计算以及梁柱节点处梁的抗弯加固等。本文通过相应试验对上述问题开展了以下研究工作：1．模拟实际构件的加固及受力过程，对在不同荷载作用下外贴CFRP加固梁进行了抗弯性能试验研究。试件包括16根外贴CFRP加固梁和2根对比梁。试验参数为：纵筋配筋率、CFRP加固量、黏贴纤维布时的预载水平。根据试验结果，对影响加固构件抗弯性能的因素进行了详细地分析；分析了构件加固时所受预载水平对其加固后抗弯性能的影响规律及其机理：在现有纤维片(板)材加固钢筋混凝土梁变形计算方法的基础上，提出了修正的截面惯性矩计算公式，通过与试验结果对比，检验了修正公式的合理性。2．为了考察节点处梁的负弯矩区段CFRP片材加固后的抗弯性能及节点处CFRP片材的锚固方式，进行了9根CFRP片材加固梁和1根对比梁的试验。试验参数包括：锚固方式、CFRP加固量和加固时预载的水平。根据试验结果详细地分析了加固后梁的抗弯承载力和变形性能；通过对不同的锚固方式的对比分析，提出了合理的节点锚固方法。3．针对FRP片材加固钢筋混凝土梁出现剥离破坏这一模式，对ACI440和CECS146规定的承载力计算方法和现有的剥离承载力计算模型进行了对比研究。计算结果与试验结果(发生剥离破坏的碳纤维片材加固钢筋混凝土梁)进行了对比分析，归纳总结了现有计算方法存在的问题，为进一步研究如何合理确定纤维片材加固受弯构件的剥离承载力提供了方向。4．为了研究FRP片材的剥离破坏机理，在9根加固梁试验中设计了CFRP片材的应变测试方案，记录了试验全过程中CFRP片材的应变分布。通过对CFRP片材应变分布规律及试件破坏过程的分析，研究了由弯剪裂缝引起的CFRP片材剥离破坏的机理；建立了由弯剪裂缝引起剥离破坏时的剥离承载力计算模型；通过文献收集了发生此类剥离破坏的63根加固梁的试验数据，通过与这些试验数据的对比，检验了所提出计算模型的合理性。5．为了解决梁柱节点处梁的抗弯加固受结构使用功能和空间等因素的制约，进行了6根在梁侧黏贴碳纤维片材加固梁和1根对比梁的抗弯性能试验。试验参数为CFRP加固量、CFRP的布置方式及节点处CFRP片材的锚固方式。采用试验结果，分析了加固后梁的抗弯性能及节点处CFRP片材的锚固方式。更多还原

【Abstract】 It has been manifested both by experiment and engineering applications that FRP laminate (plate) used as a substitute for steel plate is very effective and efficient in strengthening concrete structures. Consequentaly a lot of achievements have been made in this field during the past two decades. However, as a new developing retrofit and rehabilitation technique, there are still many problems needed to be studied, such as, is there any effect of preload level on the flexural behavior of strengthened RC beam at the time of strengthening; how to evaluate the deflection of RC beams strengthened under different external load; what is the mechanism of intermediate crack (IC) induced debonding failure, and how to evaluate its initial debonding strength; and the flexural strengthening method of the beam at beam-column joint, and so on. Based on these problems, the following studies had been carried out in this dissertation.1. To investigate the flexural behavior of CFRP-strengthened RC beams under different preload level, 16 strengthened beams and 2 control beams were tested. The test variables were rebar ratio, number of plies of CFRP laminates, and preload level at the time of strengthening. Based on the test results, this dissertation presents a detailed analysis on the factors affecting the flexural performance of strengthened beams. Further analysis was carried on how and why the stiffness varied with the change of preload level. At last, an improved formula for evaluating the effective second inertia of moment was proposed and verified with test results reported in literature.2. Ten RC beams with beam-column joint were tested to investigate thier flexural behavior of the hogging moment region strengthened with CFRP laminate, and to find out a suitable anchorage system to anchor CFRP laminates at the joint. The test parameters included anchorage system, number of plies of CFRP laminates, and preload level. The flexural behavior of the strengthened beams was discussed and an appropriate anchorage system was proposed by comparison of different anchorage systems.3. The provisions for determining flexural strength of FRP-strengthened RC beams in ACI440.2R and CECS146, as well as the existing debonding strength models were discussed based on the test results of FRP-strengthened beamswith IC debonding failure. The objective is to assess whether these guides and models are reliable to prevent debonding failure, and to give some information for further research.4. Nine CFRP-strengthened RC beams were tested to examine the strain distribution along CFRP laminate and the crack pattern in the strengthened RC beam. The objective is to make best understanding of the mechanism of intermediate crack (IC) induced debonding. By analyzing the test results, the debonding mechanism had been made much clear, and a debonding strength model was proposed and verified by test results of 60 FRP-strengthened RC beams with IC debonding failure.5. Six cantilever RC beams of side bonding CFRP laminates and 1 control beam were tested to investigate the flexural behavior and appropriate anchorage system at the joint. The intention of side bonding was to overcome the restriction of serviceability as well as space limitation of the strengthened structure. The test variables included number of plies of CFRP laminate, configuration of CFRP laminates, and anchorage systems at the joint. Based on the test results, the flexural behavior and anchorage systems were analyzed.更多还原