Performance and damage evaluation of RC beams under impact loading
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摘要: 基于落锤冲击试验，通过数值模拟研究钢筋混凝土梁在冲击荷载下的抗冲击性能和损伤机理。针对冲击荷载局部效应明显和持时短暂等特点，提出基于截面损伤因子的损伤评估方法；采用参数分析方法研究了箍筋间距、边界条件、冲头形状和面积以及冲击位置对钢筋混凝土梁的动态响应和损伤程度的影响。结果表明：基于截面的损伤评估方法能够比较直观地描述梁体损伤沿长度方向的分布；端部的固支约束可以有效地改变钢筋混凝土梁的耗能机制，并能提高梁的抗冲击承载潜力；冲击位置会直接影响梁体的裂缝分布和破坏模式；碰撞接触面积和冲头形状也对梁的损伤分布具有一定的影响。Abstract: In this work, we investigated the impact resistance and damage mechanism of RC beams under impact loading using numerical simulation based on impact tests. We established a damage evaluation method based on the cross-sectional damage factor with the finiteness of the impact area and impact time taken into consideration, and analyzed the influence of impact parameters on the dynamic response and damage level of RC beams by conducting examination of such parameters as the stirrups pacing, boundary condition, impact or nose shape, and impact location. The results indicate that the damage assessment method proposed in this study can visually describe the damage distribution along the length of RC beams, that the end fixed constraints can effectively change the energy dissipation mechanism of RC beams and improve the impact resistance capability, that the impact location directly affects the beams' crack distribution and failure mode, and that the impact area and nose shape have a certain influence on the damage distribution of RC beams.
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Key words:
- RC beams /
- impact loading /
- dynamic response /
- energy dissipation mechanism /
- damage evaluation
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图 5 不同冲击高度时RC梁的裂缝分布对比
Figure 5. Comparison of RC cracking patterns at different impact heights
图 6 不同冲击高度下碰撞力和跨中挠度时程曲线对比
Figure 6. Comparison of impact force and midspan deflection at different impact heights
图 8 不同碰撞时刻RC梁截面损伤因子
Figure 8. Sectional damage factors of RC beams at different impact time
图 9 不同冲击高度时RC梁截面损伤因子
Figure 9. Sectional damage factors of RC beamsat different drop heights
图 12 不同箍筋间距下RC梁的动态损伤
Figure 12. Dynamic damage of RC beams at different spacings of stirrups
图 13 不同箍筋间距下RC梁的截面损伤因子
Figure 13. Sectional damage factors of RC beams at different spacings of stirrups
图 14 不同边界条件下RC梁的动态损伤
Figure 14. Dynamic damage of RC beams under different boundary conditions
图 15 不同边界条件下RC梁的截面损伤因子
Figure 15. Sectional damage factors of RC beams under different boundary conditions
图 16 不同边界条件下RC梁的碰撞力和跨中挠度时程曲线
Figure 16. Histories of impact force and midspan deflection of RC beams under different boundary conditions
图 17 不同边界条件下RC梁各部分材料的能量耗散
Figure 17. Energy dissipation of the different parts under different boundary conditions
图 19 不同冲击体下RC梁的碰撞力和跨中挠度时程曲线
Figure 19. Histories of impact force and midspan deflection of RC beams with different impactors
图 20 不同冲击体下RC梁的碰撞力和跨中挠度时程曲线
Figure 20. Histories of impact force and midspan deflection of RC beams with different impactors
图 21 不同撞击位置下RC梁的动态损伤
Figure 21. Dynamic damage of RC beams with different impact positions
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