钢筋混凝土梁柱节点动态力学性能研究

发布时间：2018-01-13 10:56

本文关键词：钢筋混凝土梁柱节点动态力学性能研究　出处：《大连理工大学》2015年博士论文　论文类型：学位论文

【摘要】：受材料率敏感性的影响,钢筋混凝土构件也具有率敏感效应,其刚度、承载力在不同加载速率水平下均有所不同。然而,以往的研究多集中于混凝土和钢筋材料率效应的研究,有关梁柱节点快速加载下的研究相对较少。基于上述考虑,采用位移控制方式加载,对钢筋混凝土梁柱节点开展了动态试验,以更好地理解加载速率对梁柱节点动态力学性能的影响。主要研究内容总结如下： (1)根据钢筋混凝土结构的延性设计准则,推导了往复荷载作用下梁截面混凝土受压区高度的取值。对简化软化拉-压杆模型的斜压杆倾角、斜压杆高度、埋置于混凝土内钢筋的屈服应力以及软化系数进行了调整,对抗剪通用分析模型的模型系数和边节点类型系数进行了调整。根据库伦破坏准则、莫尔圆理论、节点组合体的受力模型,推导了剪压复合受力状态下混凝土的抗剪强度计算模型。此外,运用二项式逻辑回归模型和简化软化拉-压杆模型分别预测了梁柱节点的破坏形态以及节点核心区裂缝的发展。 (2)对比了应变率水平不同计算方法的可行性以及梁柱中节点抗剪承载力不同计算公式的合理性,研究了加载速率和轴压比对梁柱中节点动态力学性能的影响。通过多元线性回归分析,给出了梁柱中节点水平抗剪承载力动态增长因子的经验公式。研究结果表明：随轴压比的提高,节点核心区斜裂缝与竖向轴力的夹角减小；随加载速率或轴压比的提高,节点组合体内的裂缝数量逐渐减少,且梁端塑性铰区混凝土损伤加重,节点核心区混凝土损伤减弱；节点组合体的承载力随加载速率的提高而增大,且屈服荷载的增长幅度较极限荷载的增长幅度更明显；随加载速率的提高,钢筋与混凝土之间的黏结滑移更明显,但节点组合体的延性没有变化；随加载速率或轴压比的提高,节点组合体的刚度退化加剧,耗能增多；简单地在拟静态设计公式中采用钢筋与混凝土动态强度的方法计算梁柱中节点的抗剪承载力是偏于不安全的,往往会过高估计梁柱中节点的抗剪承载力。轴压比和加载速率对梁柱边节点的力学性能有类似的影响规律。 (3)通过有限元分析软件ABAQUS,采用混凝土损伤塑性模型,可以有效地模拟钢筋混凝土梁柱节点在快速加载情况下的应变率效应,数值分析得到的荷载。位移骨架曲线以及节点组合体的抗剪承载力与试验结果基本吻合。此外,配箍率对钢筋混凝土梁柱节点混凝土的损伤程度以及应力分布有一定的影响,节点组合体的屈服荷载和极限荷载均随节点核心区箍筋间距的增大而降低,配箍率减小后,极限荷载的降低幅度较屈服荷载的降低幅度更加明显。
[Abstract]:Affected by the sensitivity of material rate, reinforced concrete members also have rate-sensitive effect, its stiffness and bearing capacity are different at different loading rate levels. Most of the previous studies focused on the concrete and reinforced material rate effect, but the study of Liang Zhu joint under rapid loading is relatively few. Based on the above considerations, the displacement control method is used to load. In order to better understand the effect of loading rate on the dynamic mechanical properties of reinforced concrete Liang Zhu joints, the main research contents are summarized as follows: 1) according to the ductility design criterion of reinforced concrete structure, the height of concrete compression zone of beam section under reciprocating load is deduced. The yield stress and softening coefficient of the steel bar embedded in concrete are adjusted, the model coefficient and the type coefficient of edge joint of the general analysis model of resisting shear are adjusted. According to the Coulomb failure criterion, the Mohr circle theory is used. In addition, the shear strength calculation model of concrete under shear-compression is derived. By using the binomial logic regression model and the simplified softening tension-compression model, the failure patterns of the beam-column joints and the development of cracks in the core zone of the joints are predicted, respectively. The feasibility of different calculation methods of strain rate level and the rationality of different formulas for calculating the shear capacity of joints in Liang Zhu are compared. The effects of loading rate and axial compression ratio on dynamic mechanical properties of beam-column joints are studied. The empirical formula of dynamic growth factor of horizontal shear bearing capacity of joints in Liang Zhu is given. The results show that the angle between oblique crack and vertical axial force decreases with the increase of axial compression ratio. With the increase of loading rate or axial compression ratio, the number of cracks in the joint decreases gradually, and the damage of concrete in the plastic hinge region of the beam end is aggravated, and the damage of concrete in the core area of the joint is weakened. The bearing capacity of the joint assembly increases with the increase of loading rate, and the increase of yield load is more obvious than that of ultimate load. With the increase of loading rate, the bond slip between steel bar and concrete is more obvious, but the ductility of the joint assembly does not change. With the increase of loading rate or axial compression ratio, the stiffness degradation of the node assembly increases and the energy consumption increases. In the pseudo-static design formula, it is not safe to calculate the shear capacity of beam-column joints by the method of dynamic strength of steel bar and concrete. The shear capacity of Liang Zhu joints is often overestimated, and the axial compression ratio and loading rate have a similar effect on the mechanical properties of Liang Zhu side joints. 3) by using finite element analysis software Abaqus and concrete damage plastic model, the strain rate effect of reinforced concrete beam-column joints under rapid loading can be effectively simulated. The load, displacement skeleton curve and shear bearing capacity of the joint assembly obtained by numerical analysis are in good agreement with the experimental results. The ratio of hoop has a certain influence on the damage degree and stress distribution of the reinforced concrete Liang Zhu joint concrete. The yield load and ultimate load of the joint assembly decrease with the increase of stirrups spacing in the core area of the joint. When the hoop ratio decreases, the reduction of ultimate load is more obvious than that of yield load.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU375

【参考文献】