# Evaluation of the Effect of Temperature (20–700 °C) on the Properties of Prestressing Steel Using AE Signals and FEM Analysis

## TL;DR

This study shows how high temperatures affect prestressing steel and uses acoustic emission signals to detect damage, helping assess structural safety after fires.

## Contribution

AE parameters were first correlated with ε22 strain and von Mises stress to determine load-bearing capacity loss after fire exposure.

## Key findings

- High temperatures cause strength degradation and shift failure mechanisms in prestressing steel.
- AE parameters (Counts to Peak, RA-value) effectively identify the onset of material damage.
- A multi-criteria diagnostic indicator was proposed to assess steel condition after fire exposure.

## Abstract

What are the main findings?
High temperature causes significant strength degradation and changes the failure mechanism.AE parameters (Counts to Peak, RA-value) effectively identify the onset of damage.

High temperature causes significant strength degradation and changes the failure mechanism.

AE parameters (Counts to Peak, RA-value) effectively identify the onset of damage.

What is the implication of the main finding?
AE was correlated with the ε22 strain and von Mises stress (FEM).A criterion was developed to determine the moment of load-bearing capacity loss after fire exposure.

AE was correlated with the ε22 strain and von Mises stress (FEM).

A criterion was developed to determine the moment of load-bearing capacity loss after fire exposure.

The study presents a comprehensive analysis of the effects of high temperatures (500 °C and 700 °C) on the microstructure, mechanical properties, and acoustic emission (AE) parameters of cold-drawn prestressing steel. The investigations included mechanical testing, AE signal acquisition, and numerical verification using the finite element method (FEM). It was demonstrated that increasing temperature leads to significant microstructural changes (pearlite spheroidisation, carbide coarsening), resulting in strength degradation and a shift in the failure mechanism from quasi-brittle (initial state) to transitional (500 °C), and finally to ductile (700 °C). For the first time, AE parameters (Counts to Peak and RA-value) were correlated with local axial strains ε22 and von Mises equivalent stress, enabling the identification of the moment of onset load-bearing capacity loss and the determination of critical material damage thresholds. A multi-criteria diagnostic indicator was proposed to assess the condition of prestressing steel after fire exposure. The results confirm the high potential of AE as a non-invasive tool for evaluating the safety of prestressing tendons and cables in reinforced concrete structures subjected to overheating or fire.