Measuring Three-Dimensional Temperature Distributions in Steel-Concrete Composite Slabs Subjected to Fire Using Distributed Fiber Optic Sensors.

Yi Bao,Genda Chen,Christopher M. Smith,Matthew S. Hoehler,Matthew Bundy

doi:10.3390/s20195518

Abstract

Detailed information about temperature distribution can be important to understand structural behavior in fire. This study develops a method to image three-dimensional temperature distributions in steel–concrete composite slabs using distributed fiber optic sensors. The feasibility of the method is explored using six 1.2 m × 0.9 m steel–concrete composite slabs instrumented with distributed sensors and thermocouples subjected to fire for over 3 h. Dense point clouds of temperature in the slabs were measured using the distributed sensors. The results show that the distributed sensors operated at material temperatures up to 960 °C with acceptable accuracy for many structural fire applications. The measured non-uniform temperature distributions indicate a spatially distributed thermal response in steel–concrete composite slabs, which can only be adequately captured using approaches that provide a high density of through-depth data points.

Highlights

Material temperature distribution can play a significant role in the safety and durability of civil engineering structures
After a heat release rate of 200 kW was achieved, popping sounds were heard from the specimen; no cracking or spalling was observed on visible surfaces
Temperature distributions were measured using distributed fiber with optictraditional sensors installed in steel–concrete composite slab specimens exposed to fire

Summary

Introduction

Material temperature distribution can play a significant role in the safety and durability of civil engineering structures. Temperature affects the energy efficiency of the building [1] and large temperature gradients can generate or aggravate internal stresses that may cause damage [2]. The damage induced by thermal effects can be critical in large concrete structures, such as dams, because of the significant heat released during the cement hydration process [3]. During an extreme event, such as a building fire, the mechanical properties of construction materials and the load-carrying capacity and stability of structural members (beams, columns, slabs, and joints) are reduced at elevated temperatures [4,5]. It is of great importance to assess the temperature distribution of structures at different stages of their life cycle.

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Discussion

Conclusion