Full-Scale Prestress Loss Monitoring of Damaged RC Structures Using Distributed Optical Fiber Sensing Technology

Chunguang Lan,Jinping Ou,Zhi Zhou

doi:10.3390/s120505380

Abstract

For the safety of prestressed structures, prestress loss is a critical issue that will increase with structural damage, so it is necessary to investigate prestress loss of prestressed structures under different damage scenarios. Unfortunately, to date, no qualified techniques are available due to difficulty for sensors to survive in harsh construction environments of long service life and large span. In this paper, a novel smart steel strand based on the Brillouin optical time domain analysis (BOTDA) sensing technique was designed and manufactured, and then series of tests were used to characterize properties of the smart steel strands. Based on prestress loss principle analysis of damaged structures, laboratory tests of two similar beams with different damages were used to verify the concept of full-scale prestress loss monitoring of damaged reinforced concrete (RC) beams by using the smart steel strands. The prestress losses obtained from the Brillouin sensors are compared with that from conventional sensors, which provided the evolution law of prestress losses of damaged RC beams. The monitoring results from the proposed smart strand can reveal both spatial distribution and time history of prestress losses of damaged RC beams.

Highlights

During the past decades, prestressing techniques were frequently used in the modern buildings to reduce the deadweight of structures and improve their durability and reliability
In order to save channel numbers of Brillouin demodulator and test time, the optical fiber sensors of loaded and unloaded beams were connected in the data acquisition process
Laboratory tests of two similar beams with different damages were used to verify the concept of full-scale prestress loss monitoring of damaged beams using the smart steel strands

Summary

Introduction

During the past decades, prestressing techniques were frequently used in the modern buildings to reduce the deadweight of structures and improve their durability and reliability. Typical application examples can be seen in the construction of bridges and nuclear reactor containments [1,2]. Considering that existing actual stress in tendons is related to the active state of prestressed concrete structures, the prestress loss is of paramount importance. Prestress losses are considered finished with the construction stage and are ignored during the in-service phase. With the rapid development and wide application of concrete additives, prestressed concrete structures can be in-service before prestress losses have finished. Prestress losses increase with the damage to the prestressed concrete structures [3], so it is very important to examine the evolution law of prestress losses in damaged prestressed structures

Methods

Results

Conclusion