Concrete Stress Block Parameters for High-Strength Concrete : Recent Developments and Their Impact

Piezoelectric-based seismic stress monitoring provides an innovative approach to assessing the health of concrete structures during earthquakes. In this research, we evaluate the application of piezoelectric-based smart aggregate (SA) sensors for monitoring the seismic stress on high-strength concrete columns. The principle behind using smart aggregates for seismic stress monitoring is based on the assumption that concrete stress can be reliably predicted by the average output voltages of a limited number of embedded smart aggregates within an acceptable margin of error. This experiment is designed to evaluate the effects of meso-scale randomness on high-strength concrete and the effects of different loading paths on the proposed smart aggregate. Loading–unloading loops of increasing amplitude at the nonlinear stage and monotonic loading to failure were carried out on four high-strength concrete cylinders. Each specimen had six smart aggregates embedded. A statistical analysis based on the test results determined the sensitivity curve during the loading–unloading and the full-range damage processes. Monitoring errors of concrete stress monitored by smart aggregate during the pre- and post-peak stages were also discussed. The research concludes that there is the potential for deploying smart aggregate in engineering applications to monitor seismic stress on high-strength concrete structures.

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Numerical Investigation of Stress Block for High Strength Concrete Columns

Civil Engineering Journal ◽

10.28991/cej-2020-03091522 ◽

2020 ◽

Vol 6 (5) ◽

pp. 974-996

Author(s):

Nizar Assi ◽

Husain Al-Gahtani ◽

Mohammed A. Al-Osta

Keyword(s):

Finite Element ◽

Intensity Factor ◽

Finite Element Model ◽

High Strength Concrete ◽

Analytical Approach ◽

High Strength ◽

Element Model ◽

Strength Concrete ◽

Stress Block ◽

The Finite Element Model

This paper is intended to investigate the stress block for high strength concrete (HSC) using the finite element model (FEM) and analytical approach. New stress block parameters were proposed for HSC including the stress intensity factor (α1) and the depth factor (β1) based on basic equilibrium equations. A (3D) finite element modeling was developed for the columns made of HSC using the comprehensive code ABAQUS. The proposed stress parameters were validated against the experimental data found in the literature and FEM. Thereafter, the proposed stress block for HSC was used to generate interaction diagrams of rectangular and circular columns subjected to compression and uniaxial bending. The effects of the stress block parameters of HSC on the interaction diagrams were demonstrated. The results showed that a good agreement is obtained between the failure loads using the finite element model and the analytical approach using the proposed parameters, as well as the achievement of a close agreement with experimental observation. It is concluded that the use of proposed parameters resulted in a more conservative estimation of the failure load of columns. The effect of the stress depth factor is considered to be minor compared with the effect of the intensity factor.

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