Abstract
Dynamic Increase Factor (DIF) due to strain rate effect was examined with documented experimental work done by Razaqpur, et al. In the experiment work, two 1000 × 1000 × 70 mm reinforced concrete slabs were constructed. The slabs were subjected to blast loads generated by the detonation of either 22.4 kg or 33.4 kg of ANFO located at a 3.0 m standoff. Blast wave characteristics, including incident and reflected pressures and reflected impulses were measured. The slabs were modeled by explicit analysis with or without strain rate effect to study their behavior under blast load to compare their predicted and observed behavior. The predicted post-blast damage and mode of failure for each model is compared with the observed damage of experimental work. It was concluded that when the dynamic increase factor added to concrete and reinforcement materials due to strain rate effect, the behavior of model under blast load become closer to experimental work.
Highlights
Since testing of structures under the effect of real explosives requires complex instrumentation and a safe test range, it is not always feasible to carry out a large number of such tests
The comparison between the field test results for the slabs subjected to a detonation of 33.4 kg of (ANFO) ma266
Terial generally compared well with the results of the explicit analysis using Ls-Dyna. it is possible to study the model after total failure where the model become unstable, i.e. explicit solver provide better presentation for blast load than implicit solver
Summary
Since testing of structures under the effect of real explosives requires complex instrumentation and a safe test range, it is not always feasible to carry out a large number of such tests. (2014) Strain Rate Effect on the Response of Blast Loaded Reinforced Concrete Slabs. The objective of this paper is to compare the observed behavior of reinforced concrete panels, subjected to nominally similar blast loads, with their predicted behavior using explicit analysis computer program Ls-Dyna for the following material models: 1) Static stress-strain curve for concrete and steel material; 2) Stress-strain curve for concrete and steel material in conjunction with strain rate effect. A new stiffness matrix is constructed, and the increment of load (or displacement) is applied to the system. This method does not enforce equilibrium of the internal structure forces with the externally applied loads. Concrete exhibits an enigmatic phenomenon of increased resistance when it is loaded at a very high rate as explained below
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