Behavior of high-strength concrete plates under impact loading

Murtiadi, Suryawan (1999) Behavior of high-strength concrete plates under impact loading. Masters thesis, Memorial University of Newfoundland.

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Abstract

High-strength concrete plates are frequently used in various structural engineering systems and varieties of civil engineering applications. A research program was carried out at Memorial University of Newfoundland to investigate the behavior of high-strength concrete two-way plates subjected to impact loading. The research program included both experimental investigation and numerical investigation. -- The current research includes an experimental investigation on sixteen concrete plates with dimension of 950x950 mm and 100-mm thickness. The plates were supported by a special frame designed for this investigation. The support frame is made from concrete and steel with free opening of 700x700 mm. Normal-strength and high-strength concrete plates were tested under two end conditions, i.e. fixed and simply supported. All of the specimens were two-way reinforced plates with reinforcement ratio that varied from 1%-2.5% in tension face and 0.7%-0.8% in compression face . A rigid projectile was used to apply the impact load to the tested reinforced concrete specimens. The rigid projectile was a solid steel cylinder with 220-kg mass and 304.5 mm diameter contact area. The projectile was dropped from a variable height of up to 4 m. An accelerometer with ± 200-g capacity was attached to the cylinder steel to record the actual test acceleration. A data acquisition system based on a personal computer acquired the data at a sampling rate of 1000 Hz. The structural behavior with respect to displacement, concrete and steel strains, failure mode, and energy absorption were examined. The effect of dynamic loading, concrete strength, reinforcement ratio, and support patterns were the test parameters. -- A numerical investigation was conducted to evaluate the test results with respect to the North American code and some European design codes. A linear elastic fracture mechanics impact load expression was used to evaluate the effect of rate of loading on the dynamic behavior of high-strength concrete plates. Based on the experimental test results it has been found that the punching failures of the impact loading were about twice the static punching shear capacity. The critical velocities of perforation can be estimated accurately for all high-strength concrete specimens according to CEB dynamic code expression. The ratio of impact versus static fracture energy for high-strength concrete plate was found to be much higher than that for normal-strength concrete. Therefore, high-strength concrete plates are considered to be more efficient than normal-strength concrete plates under impact loading.

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