Abstract
Problem statement: Rate dependence of the newly developed Very-High-Strength-Concrete (VHSC) composites has received little or no attention so far. Approach: In this research, the bond-slip mechanisms of four types of steel fibers embedded in VHSC matrices were investigated through single-fiber pullout tests with the loading rates and matrix strengths are the primary variables. This study presented the experimental results of steel fiber-matrix bond characteristics and discussed the influence of loading rates on the pullout behavior. Results: The results were measured in terms of peak loads and total fiber pullout work or dissipated bond energy. Results indicated that the increase in pullout rate increases both peak load and total pullout work for all deformed fibers but had no effect on smooth, unreformed fibers. Conclusion/Recommendations: De formed and smooth fibers exhibit different rate sensitivities. The variation in response was attributed to the fiber end conditions. It is recommended that (1) additional experimental tests should be performed at other loading rates and (2) an analytical model should also be developed to analyze the rate effect on the interfacial deboning process of VHSC composites.
Highlights
Fiber-reinforced Very High Strength Concrete (VHSC) composites are promising materials for use in a wide variety of civil and structural engineering applications
The primary objective of this study is to provide experimental test data of the effect of loading rate on the pullout behavior of steel fiber reinforced VHSC composites
Results indicated that for fibers embedded in VHSC with embedment lengths of 6.35 and 12.7 mm, the peak loads and pullout works are higher for the higher pullout rate
Summary
Fiber-reinforced Very High Strength Concrete (VHSC) composites are promising materials for use in a wide variety of civil and structural engineering applications. Kim et al (2009) investigated the correlation between rate sensitivity in single fiber pullout behavior and rate sensitivity at the corresponding High Performance Fiber Reinforced Cementations Composites (HPFRCC). Their results included the effect of loading rate on the first cracking strength, post cracking strength and strain capacity as a function of fiber type, fiber volume fraction and matrix strength. Zhouhua et al (2002) Performed dynamic fiber push-out experiments on model single fiber composite systems They studied the effect of loading rate, fiber length and surface roughness on the push-out behavior and concluded that the maximum push-out force increases with increasing loading rate.
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