【作者】 胡春红；

【导师】 赵铁军； Wittmann F.H.；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2013， 博士

【摘要】 工程结构由于各种原因产生劣化，致使耐久性不足而亟需修复。应变硬化水泥基复合材料（Strain Hardening Cementitious Composite，简称SHCC）具有应变硬化和多微缝开裂特征，其超高的韧性和良好的裂缝控制能力能够满足结构加固修复对裂缝宽度控制的要求。采用SHCC对既有混凝土结构进行加固修复，则可以避免出现采用脆性的水泥基材料来修复劣损结构，短期内修复材料却再次开裂或剥落的发生。目前国内外对SHCC修复既有混凝土结构界面粘结性能的研究还十分不足，本文通过试验研究和理论分析开展了以下研究工作：1．针对目前SHCC材料在国内尚未普及应用，其配合比、制作方法及试件形式尚未形成统一标准，本文利用普通外夹式试验机对龄期为28天的SHCC哑铃型试件进行单轴拉伸试验，对不同配合比SHCC的单轴拉伸性能进行了探讨，获得了各配合比SHCC的单轴拉伸应力—应变曲线。通过对比，C3配合比SHCC稳态开裂性能较好，极限拉应变可达到甚至超过3%，同时还具有成本低的优点，被确定用于后期试验中；然后对4组12个C3配合比SHCC试件进行了试验研究和深入分析，在引入名义初裂强度和名义初裂应变的基础上提出了SHCC的双线性简化模型。2．通过对59个SHCC与老混凝土Z型粘结试件进行试验研究，对不掺加界面剂的粘结试件的界面抗剪性能进行了考察。主要探讨了界面粗糙度对粘结界面抗剪强度的影响规律；通过回归分析，建立了抗剪强度与界面粗糙度之间的函数关系；同时通过测读粘结面两侧的相对位移，得到了粘结面的剪应力—滑移曲线。3．通过52个楔形劈裂粘结试件，对SHCC与老混凝土粘结界面的抗拉性能及断裂能进行了试验研究。主要探讨了界面粗糙度对粘结界面抗拉强度和断裂能的影响规律，建立了抗拉强度和断裂能与界面粗糙度的函数关系式。4．通过7根SHCC修复钢筋混凝土梁抗弯性能试验，考察了修复梁的破坏特征，揭示了修复梁发生界面粘结破坏的原因、过程及其破坏机理；并在此基础上，给出了界面粘结破坏承载力计算方法和防止界面粘结破坏发生的具体措施。5．通过7根SHCC修复钢筋混凝土梁和3根普通钢筋混凝土梁的抗弯性能试验，研究了SHCC修复钢筋混凝土梁的裂缝情况。主要考察了界面粗糙度、修复层厚度和混凝土强度等因素对修复梁纯弯段内裂缝间距和裂缝宽度发展的影响规律；分析了弯曲荷载作用下两种材料的裂缝发生、发展情况，揭示了修复梁的裂缝发展机理，并在此基础上，对原有钢筋混凝土梁的裂缝计算模型进行适当修正，建立了SHCC修复钢筋混凝土梁的实用裂缝计算模型，通过对比理论计算值和实测值，验证了所提出的计算模型具有较高的精度。6．通过SHCC修复钢筋混凝土梁的抗弯性能试验，考察了界面粗糙度、修复层厚度和混凝土强度等因素对修复梁刚度变化的影响规律；基于刚度解析法，建立了修复梁在正常使用阶段的刚度解析模型；利用最小刚度原则建立了修复梁跨中挠度计算公式，并将理论计算结果与试验构件跨中挠度实测值进行对比，结果表明，提出的刚度计算模型及其中参数的取值具有较高精度，可以作为工程设计的参考。更多还原

【Abstract】 Engineering structures need urgently to be repaired because the durabilily of them islack due to various reasons. Strain hardening cementitious composite (SHCC for short)has strain-hardening and multiple micro-cracking characteristics, it is able to meet therequirements of strengthened and repaired structures because of its ultra high toughnessand good crack control capacity. So that repair materials crack or spalling again frommatrix can be avoided if SHCC is used to strengthen or repair the deteriorated concretestructures. At present, research on interfacial bonding behavior of RC members repairedwith SHCC is not enough at home and abroad, so the following research work is mainlydone in this thesis:1. Experimental study on uniaxial tensile performance of SHCC was carried out usingtest machine with external clip. Uniaxial tensile performance of SHCC with differentmixture proportion was discussed and uniaxial tensile stress-strain curves of differentSHCC were drawn. By comparing the test results, the stable cracking behavior of C3was good, its ultimate tensile strain could reach to3%and its cost was lowest, so C3was used in later test. And then, the futher test and analysis of C3were done, bilinearmodel was put forward on the basis of nominal initial cracking strength and initialstrain.2. Experimental research on fifty-nine Z-shape bonding specimens of SHCC and oldconcrete was carried out, interface shear performance of bonding specimens wasinvestigated. The influence of interface roughness on interface shear strength was discussed. Function relationship between interface roughness and shear strength wasbuilt by using regression method. And the shear stress-slip curve of interface was gainedthrough measuring the relative displacement of both sides of bonding surface.3. Experimental research on interface tensile performance and fracture energy wascarried out through fifty-two wedge splitting bonding specimens of SHCC and oldconcrete. The affect of interface roughness on interface tensile strength and fractureenergy was mainly discussed and the function relationship between interface roughnessand interface tensile strength or fracture energy was put forward.4. Experimental study on bending performace through seven RC beams repaired withSHCC was carried out. The failure characters of repair beams were investigated. Thecauses, process and mechanism of inface bonding failure of repair beams were revealedand then a method to calculate the bearing capacity of interface bonding failure andmeasures preventing bonding failure were put forward.5. Research on crack of RC beams repaired with SHCC was done through bendingtest of seven repair beams and three contrast beams. The influence of interfaceroughness, thickness of repair layer and concrete strength on crack spacing and crackwidth in pure bending area of repair beams was mainly investigated. The occurrenceand development of cracks of two materials (SHCC and concrete) under bending loadwere analyzed. The development mechanism of cracks of repair beams was revealedand then a practical method was put forward for calculating the crack spacing and widthof repair beams. At last, it was verified that the calculating model had higher accuracyby comparing the theoretical result and the experimental result.6. The influence of interface roughness, thickness of repair layer and concretestrength on the stiffness of RC beams repaired with SHCC was investigated throughbending experiment of seven repair beams and three contrast beams. An applicablestiffness analytical equation was drawn to calculate the stiffness of SHCC-repaired RCbeams according to the equilibrium and compatibility conditions. The analyticalequation of deflection at the midspan was built based on the least stiffness principle.The predictions of the deflection at the midspan using the proposed stiffness equationwere compared and shown to agree well with the experiment results.更多还原