【作者】 牟晓光；

【导师】 王清湘；

【作者基本信息】 大连理工大学 ， 结构工程， 2006， 博士

【摘要】 采用强度高、延性好、高质量的预应力钢筋作为配筋的预应力混凝土结构已成为大跨度、重荷载、结构性能优良的现代建筑发展的必然趋势。预应力混凝土用光圆钢棒、异形钢棒及螺旋肋钢丝就是近年来开发的高强预应力钢筋新品种。随着预应力钢筋强度的提高及钢筋外形的变化,加之抗震设计必须考虑的粘结退化,使得钢筋与混凝土之间的粘结锚固问题愈显突出。本文通过试验研究、理论分析和数值模拟,着重研究了光圆钢棒、异形钢棒和螺旋肋钢丝的粘结锚固性能,完成了以下工作: 1.通过6种不同外形钢筋的拉拔试件在单调加载下的拔出试验,研究了各种钢筋不同的粘结锚固破坏全过程,分析比较了各种不同外形钢筋与混凝土粘结性能的差异,并讨论了影响粘结锚固性能的主要因素。根据试验结果,给出了新型螺旋状高强预应力钢筋的粘结强度计算公式,公式计算结果与试验结果吻合良好。 2.对4种高强预应力钢筋在锚固长度较长的情况下进行了拔出试验研究,比较了各种不同外形预应力钢筋与混凝土的粘结性能,分析了锚固长度较长情况下各种因素对粘结锚固性能的影响,并在试验研究的基础上进行可靠度分析,给出了可供工程设计参考的螺旋肋钢丝和异形钢棒的锚固长度建议值,该值与《混凝土结构设计规范》的锚固长度设计值相比减少5d～20d。 3.针对异形钢棒和螺旋肋钢丝所特有的螺旋状外形,对两者在拔出过程中均产生的明显的转动现象进行分析,进而得出螺旋状预应力钢筋与混凝土之间的粘结作用机理。 4.通过光圆钢棒、异形钢棒和螺旋肋钢丝拉拔试件在重复荷载作用下的拔出试验,比较了3种不同外形高强预应力钢筋的粘结破坏特性的差异,并给出了3种高强预应力钢筋在等幅重复荷载作用下的特征荷载值与应力水平上限的关系式。 5.基于试验所确定的钢筋与混凝土基本力学性能指标,采用弹性接触问题有限元混合法,引入无厚度接触面计算模型,按空间轴对称方法模拟了钢筋与混凝土的粘结破坏全过程,数值计算结果与试验结果拟合较好。同时,利用该数学模型得到了钢筋与混凝土界面间的粘结应力分布情况。更多还原

【Abstract】 Prestressed concrete structures with the high-strength, good-ductility and high-quality prestressed reinforcement as reinforcing bars become an inevitable trend of development of modem buildings with long-span, heavy-load and fine-structure performance. In recent years, round steel bar, deformed steel bar and helical rib steel wire for prestressed concrete are new kinds of high strength prestressed reinforcement. With the improvement of prestressed reinforcements strength and variation of surface configuration of rebar, and necessarily considering bond decay in earthquake-resistant design, problems of bond anchorage between reinforcement and concrete are getting increasingly stringent. In this paper, the bond anchorage behaviours of round steel bar, deformed steel bar and helical rib steel wire are investigated by experimental research, theoretical analysis and numerical simulation. The major contributions are summarized as follows:1. The pullout specimens of 6 different surface configurations of reinforcements are tested under monotonic loading. The whole processes of bond failure with various reinforcements are studied. The differences of bond behaviour between various surface configurations of reinforcements and concrete are analyzed. The main influences on bond anchorage performance are discussed as well. Based on the experimental results, the equation to analyze bond strength for new types of helical high-strength prestressed reinforcement is derived. The analytical results agree well with the test results.2. The pullout tests on 4 kinds of high-strength prestressed reinforcements are studied under a long anchorage length condition. The bond behaviours between various surface configurations of reinforcements and concrete are compared. The different influences on bond anchorage performance are analyzed. Based on the experimental studies, the suggested anchorage lengths of helical rib steel wire and deformed steel bar are given by reliability analysis, which can provide references for engineering design and so that the anchorage lengths could be reduced from 5d to 20d than those of Code for design of concrete structures.3. Due to defonned steel bar and helical rib steel wire with the unique helical surface configuration, the obvious rotational phenomena appear during the pullout processes. The bond mechanisms between the helical prestressed reinforcements and concrete can be explained by analyzing the rotational phenomena.4. The pullout specimens of round steel bar, deformed steel bar and helical rib steel wire are tested under repeated loadings. The differences of bond failure between 3 various surface configurations of prestressed reinforcements and concrete are compared. The relationships between characteristic loads and maximum values of stress levels are obtained under constant amplitude repeated loading.5. According to the space axisymmetric method, the whole process of bond failure between reinforcement and concrete is simulated. The basic mechanical properties of reinforcement and concrete are determined by the tests. The simulation uses the FEM mixed method for elastic contact problems, and introduces the no-thickness contact computation model. The numerical calculation results agree well with the experimental results. Meanwhile, the distribution situations of bond stresses along the interface between reinforcement and concrete are obtained by using the mathematic model.更多还原