Critical impact energy for local impact damage of hard projectile on concrete slab
Concrete is a common construction material used to build conventional, un�conventional, and sensitive structures. Great demand exists for efficient designing of concrete as protective structures against impact loading generated by natural disasters and consciously engendered unpleasant incidents...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2012
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/2478/1/24p%20QADIR%20BUX%20%40%20IMRAN%20LATIF.pdf |
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| Summary: | Concrete is a common construction material used to build conventional, un�conventional, and sensitive structures. Great demand exists for efficient designing of
concrete as protective structures against impact loading generated by natural
disasters and consciously engendered unpleasant incidents etc. When hard projectile
collides with concrete wall it is the impact energy of the projectile that makes
concrete target to deform, which means impact energy is the dominant cause of
damage in impact accidents. Hard missile impact can generate both local (penetration,
scabbing, and perforation) and global impact damage. Local damage studies
normally fall into three categories, i.e. empirical formulation, idealised analytical
models, and numerical simulations. The present study is curiously focused on the
required critical impact energy for occurrence of local impact damage in concrete
structures generated by hard projectile, via three categories i). Numerical simulation,
ii). Analytical modelling, and iii). Empirical formula The numerical simulations were conducted to determine the critical impact
energy of ogive nose hard projectile which causes maximum penetration in to the
concrete structures. The effects of diameter and CRH ratio of ogive nose hard
projectile on critical impact energy were also analysed. An analytical model is
developed to predict the required critical impact energy for spalling, tunnelling and
penetration in concrete target. A nose shape factor (Ni) also has been introduced with
empirical friction factor (Nf) in Chen and Li nose shape factor (N*
), to analyze the
effects of nose shape on critical impact energy. Furthermore, an empirical formula
also has been developed.
The early stage scabbing phenomenon has been observed through the wave
propagation in simulations with fully elastic model assumptions. The critical impact
energy required for scabbing of concrete target and the effects of diameter of projectile (d) and the target thickness (H) on critical impact energy has been
observed. An analytical model is developed based on 1-Dimensional with reflected
wave propagation, and shear assumptions. Furthermore, an empirical formula also
has been introduced.
For perforation, the penetration numerical simulations have been further
extended to achieve perforation in deep concrete against impact of ogive nose hard
projectile with CRH = (3.0, 4.25, and 6.0). The required critical impact energy and
residual impact energy has been analysed. Furthermore, the modifications in Li and
Reid (2006) perforation model also have been done. In Addition a new empirical
formula also has been introduced.
The out come of this study can be used for making design recommendation
and design procedures for determining the dynamic response of the concrete target to
prevent local impact damage |
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