碰撞冲击荷载作用下钢筋混凝土柱的损伤评估及防护技术

DAMAGE EVALUATION AND PROTECTION TECHNIQUE OF RC COLUMNS UNDER IMPULSIVE LOAD

以刚性球撞击钢筋混凝土柱为例,研究了碰撞冲击荷载作用下钢筋混凝土柱的损伤程度评估以及防护技术。在钢筋混凝土柱粘结滑移模型基础之上,提出了一种基于竖向剩余承载力的损伤评估准则,用来判定碰撞冲击荷载下钢筋混凝土柱损伤破坏程度;并定量分析了刚性球质量、初速度与结构柱损伤度的关系。针对复合截面防护的情形,对碰撞冲击荷载作用下钢筋混凝土柱防护前后的动态响应及损伤进行了分析,并对比了外粘钢板及外敷泡沫铝两种防护措施的防护效果。结果表明:刚性球质量及速度在较小范围内时,损伤度的增长速率高于质量及速度的增长速率,且以质量和速度同时增加时损伤度增长最快;当刚性球质量及速度达到一定数值后,损伤度的增长速率一般会低于刚性球质量及速度的增长速率。外粘钢板、外敷泡沫铝两种复合截面防护方法均能有效降低碰撞冲击下钢筋混凝土柱的动态响应及损伤程度,且均能使钢筋混凝土柱的整体破坏模式由弯剪破坏向弯曲破坏转变。

Damage evaluation and protection technique of reinforced concrete RC column subjected to impulsive load are studied through numerical simulation of collision between a rigid ball and the RC column. On the basis of the bond-slip model for the RC column, a damage criterion is put forward to determine the damage degree of the RC column under impact based on the residual axial load-carrying capacity of the RC column. And correlativity between damage degree of the RC column and mass, initial velocity of rigid ball is studied qualitatively. Dynamic response and damage of RC columns before and after protection are analyzed, and the protective effects of strengthening with externally bonded steel plate and foamed aluminum are compared. The results indicate that： the damage degree increases faster than the mass and initial velocity of the rigid ball when the mass and initial velocity are in a low level, and the damage degree enhances fastest as the mass and initial velocity increase simultaneously; when the mass and initial velocity of rigid ball reach a certain value, the growth rate of damage degree will be lower than the mass and initial velocity＇s. Moreover, the two protective measures externally bonding steel plate and foamed aluminum can effectively reduce the mechanical response and damage degree of the RC columns; and the protection can also transfer the global failure mode of the RC column from bending-shear failure to bending failure.