BEHAVIOUR OF AXIALLY LOADED CONCRETE COLUMNS
SUBJECTED TO TRANSVERSE IMPACT LOADS
34th Our World in Concrete and Structures (OWICs) - 2009
H M I Thilakarathna*, Queensland University of Technology, Australia
D Thambiratnam, Queensland University of Technology, Australia
M Dhanasekar, Queensland University of Technology, Australia
N J Perera, Robert Bird Groups & Queensland University of Technology, Australia
Increased industrialisation has brought to the forefront the susceptibility of concrete columns
in both buildings and bridges to vehicle impacts. Accurate vulnerability assessments are
crucial in the design process due to the possible catastrophic nature of the failures that can
occur. This paper reports on research undertaken to investigate the vulnerability of columns in low to medium rise buildings, designed according to the Australian standards. Numerical
simulation techniques were used and validation was done by using experimental results
published in the literature. The material model formulation used for validation is scrutinised
and numerical tests are preformed to examine its ability to simulate the impact conditions.
Axially loaded columns made out of grade 40 to 50 concrete with two different steel ratios are considered in the analyses. It is found that typical columns in five storey buildings, having a high slenderness ratio of 13.33, are highly vulnerable to medium velocity car impacts . The investigations are continued with different combinations of parameters to identify the means to mitigate damage. It is observed that the design option with low amount of steel significantly improves impact capacity while a higher grade of concrete considerably increases the vulnerability of the impact, contrary to what would be expected. However, further improvements can be made when smaller slenderness ratios are selected. In particular, influences of time of impact and iso-damage conditions are investigated in detail. It has also been found that vehicle impacts can be categorised next to the quasi-static loading region in typical force-impulse diagrams. This will allow numerical methods to be implemented to quantify the impact damages.