基于破坏试验的混凝土梁承载能力极限状态容许变形研究

Research on Allowable Deformation of Concrete Beams in Load-bearing Capacity Limit State Based on Failure Test

摘要:

为明确混凝土梁在承载能力极限状态下的容许变形，进而支撑基于变形的结构安全冗余解析及服役状态监测、预警、评估等工作，首先开展了1片足尺旧空心板的破坏试验；其次，通过广泛调研混凝土梁破坏试验成果，形成了包含630片梁的破坏试验成果数据库，据此分析了承载能力极限状态的平均变形水平，表征了容许变形的概率分布特征，提出了具有95%保证率的容许变形建议值。研究发现：混凝土梁在承载能力极限状态下的特征变形包括屈服变形、强化变形和破坏变形，钢筋混凝土（RC）梁三大特征变形平均水平分别为L/261.3、L/209.5和L/88.8，预应力混凝土（PC）梁三大特征变形平均水平分别为L/173.7、L/141.3和L/92.7；混凝土梁承载能力极限状态容许变形不拒绝正态分布，RC梁和PC梁在承载能力极限状态下具有95%保证率的容许变形水平可分别取为L/345、L/284。

Abstract:

To determine the allowable deformation of concrete beam under the limit state of bearing capacity and then support the analysis of structural safety redundancy based on deformation and the work of service status monitoring, early warning and evaluation, the failure test of a full size old hollow plate is carried out firstly, and then through extensive investigation of concrete beam failure test results, a database of failure test results of 630 beams is formed. On basis of this, the average deformation level of the limit state of bearing capacity is analyzed. The probabilistic distribution characteristics of allowable deformation are expressed. The proposed value of allowable deformation with a guarantee rate of 95% is put forward. The research shows that the characteristic deformations of concrete beam under the limit state of bearing capacity include the yield deformation, strengthening deformation and failure deformation. The average values of the three characteristic deformations of reinforced concrete (RC) beam are L/261.3, L/209.5 and L/88.8 respectively. For prestressed concrete (PC) beams, the average values are L/173.7, L/141.3 and L/92.7 respectively. The allowable deformation of concrete beam does not reject the normal distribution in the limit state of bearing capacity. For RC beams and PC beams, the allowable deformations with a guarantee rate of 95% in the limit state of bearing capacity can be taken as L/345 and L/284 respectively.