An efficient method to derive statistical mechanical properties of concrete reinforced with spiral-shaped steel fibres in dynamic tension

Abstract

Steel-fibre-reinforced concrete (SFRC) has been recognised as an effective solution to resist impact loading on structures. The reliable application and efficient design of SFRC structures depends on the knowledge of its mechanical properties. Since many important factors, including the locations and orientations of fibres and aggregates in concrete and the material properties of concrete matrix, are intrinsically random, the mechanical properties of SFRC present a high level of randomness. To accurately quantify them, effective statistical techniques are indispensable. Using traditional statistical techniques, a large quantity of data, from either experiments or numerical simulations, are needed to derive the correlation between the mechanical properties and the random factors. However, both ways are time-consuming and costly. Therefore, very little information regarding the statistical mechanical properties of SFRC can be found in the current literature. In this study, a kernel-based nonparametric statistical method is proposed to derive the statistical mechanical properties of SFRC with limited number of data. The behaviours of SFRC with randomly distributed spiral-shaped fibres and aggregates under impact loading are simulated using commercial software LS-DYNA. The simulation accuracy is validated by the experimental results. The influences of various volume fractions of fibres on dynamic increase factor (DIF) of the tensile strength of SFRC specimens under dynamic loadings at different strain rates are quantified through a prediction model obtained from kernel regression. The results demonstrate that the proposed method is able to estimate the DIF value of SFRC based on the tensile strength and strain rate, and to derive the statistical mechanical properties of SFRC.

Mesoscale modelling of concrete reinforced with spiral steel fibres under dynamic splitting tension

“…It should be noted that the present mesoscale model is based on the plane strain assumption. This is a reasonable assumption because the effect of aggregates and steel fibres along the axial direction of the cylindrical specimen has little effect in resisting the splitting tension (Wang et al, 2016). However, it is more realistic to consider the random distribution and orientation of aggregates and spiral fibres in three dimensions in the SFRC specimen, especially for investigations of the mechanical properties of SFRC specimen under compression.…”

“…In all the studies reviewed above, for the investigated SFRC specimens with specific volume fraction of fibres, only one mesoscale model was considered. For a less-biased examination of the influence of volume fraction of spiral fibres on the mechanical properties of SFRC material under dynamic splitting tension, Wang et al (2016) conducted statistical analysis and obtained the probability density function of the dynamic strength. However, the study focused on proving the applicability and advantage of a kernel-based non-parametric statistical method in predicting the dynamic strength of SFRC materials with limited number of samples, but the proper dosage of spiral fibres that could be beneficial for easy casting, less-scattered dynamic strength and construction cost was not investigated.…”

Upper and Lower Bounds to Pull-Out Loading of Inclined Hooked End Steel Fibres Embedded in Concrete

“…Though the averaging has removed vibrational scatter in the loading an irregularity remains in each plot which can defy an accurate prediction. Despite this, most reports on pull-out testing continue to identify a sequence of failure events within the plot of pull-out load versus fibre slip [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The first event is the region along a rising curve within which fibre debonding has occurred.…”

“…It is inevitable that concrete structures are subjected to tensile stress during their service lives whether this arises from shrinkage or from flexural bending and shear [1]. Consequently, there is a need to provide the structure with shear strength, flexural strength, ductility, and crack resistance.…”

A Novel Sensor Prototype with Enhanced and Adaptive Sensitivity Based on Negative Stiffness Mechanism

“…For monitoring weak and low frequency vibration signals, various types of advanced sensors have been developed. According to the realization principles, the sensors can be divided into: magnetoelectric sensors [20], piezoelectric sensors [21][22][23][24][25], fiber sensors [26,27], capacitive sensors, piezoresistive sensors etc. [28,29].…”