Abstract
Increased loading rates on fasteners may be caused by high ground accelerations as a consequence of e.g., nuclear explosions, earthquakes or car collisions. It was concluded by Hoehler et al. (2006) that fasteners under rapid loading rates show an increased ultimate resistance in the concrete dominant failure modes or the ultimate resistance is at least as large as under quasi-static loading. Due to the increased demand on using fasteners in steel fiber reinforced concrete (SFRC), it is intended to show how the ultimate concrete cone capacity of fasteners changes under higher than quasi-static loading rate in normal plain concrete (PC) and in SFRC. This paper presents the results of an extensive experimental program carried out on single fasteners loaded in tension in normal plain concrete and in SFRC. The test series were conducted using a servo-hydraulic loading cylinder. The tests were performed in displacement control with a programmed ramp speed of 1, 100, 1000, and 3500 mm/min. This corresponded to calculated initial loading rates ranging between 0.4 and 1600 kN/s. The results of the tension tests clearly show that the rate-dependent behavior of fasteners in SFRC with 30 and 50 kg/m3 hooked-end-type fibers fits well to the previously reported rate-dependent concrete cone behavior in normal plain concrete. Additionally, a positive influence of the fibers on the concrete cone capacity is clearly visible.
Highlights
Introduction and MotivationImpact loads acting on concrete structures or on structural components are of common occurrence.Examples for that include nuclear explosions, earthquakes and collision of vehicles
This paper presents the results of an extensive experimental program carried out on single fasteners loaded in tension in normal plain concrete and in steel fiber reinforced concrete (SFRC)
Each graph presents the results of the test series in one particular base material, namely in normal plain concrete, in SFRC with 30 kg/m3 and in SFRC with 50 kg/m3 fiber content
Summary
Introduction and MotivationImpact loads acting on concrete structures or on structural components are of common occurrence.Examples for that include nuclear explosions, earthquakes and collision of vehicles. Impact loads acting on concrete structures or on structural components are of common occurrence. Engineering structures may be subjected to functional impact loads such as pile driving. As a part of the whole, fasteners in safety relevant applications may be subjected to high loading rates and high impact loads over their service life. It is well known that concrete shows strong rate-dependent behavior. In the case of static tests and at very low loading rates i.e., sustained loads, the cracks can extend to zones in the concrete where the concrete tensile strength and/or the bond is the lowest [2]. The opening crack has enough time to follow the path of minimum resistance. If concrete is subjected to high loading rates, the fracture takes places within a very short time span (milliseconds). This, Fibers 2018, 6, 93; doi:10.3390/fib6040093 www.mdpi.com/journal/fibers
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