Distributed Fiber Optic Sensors a New Method to Reduce of Damages Caused by Various Disasters and Events in Tehran's Urban Buildings

Natural and abnormal incidents and disasters such as earthquake, flood, storm, War, terroristic and subversive acts and etc, always impose many human and financial losses in a country. The probability of occurrences of these incidents or disasters in the metropolis of Tehran is one of the major challenges and concerns of the people and the officials of the city and the country. High population density and lack of proper safety in many residencies and financial institution buildings and facilities as well as the increasing development of urban structures in the capital have led us to consider more confident approaches to prevent the possible damages and casualties. Structures such as bridge, tower, subway, water storage dam, energy transmission pipelines, financial centers, political, security and military positions are among the places in Tehran that damages would be more critical and dangerous than others. The most important actions in the crisis management and passive defense is performing the appropriate and precautionary actions before happening of such incidents. One of the newest technologies to reduce the damages and casualties is optical fiber distributed sensors.
In distributed fiber optic sensors, the laser beam is dispersed into the fiber, and some of it is reflected because of the inherent barriers inside the fiber. the incoming light is dispersed and some reflected. The presence of disturbances in the fiber path increases the reflection light and reveals the disturbance in the specific point. The vast application of these sensors in the field of defense has led to a review of some of their most commonly used types in this paper.
Findings: In distributed fiber optic sensors, by measuring the static or dynamic changes created along a fiber, temperature, pressure, stress, strain, changes will be detected over more than hundreds of kilometers fiber length.
Monitoring of large structures against cracks and fractures due to the age of structures, humidity, extreme weather conditions, corrosion as well as various disasters and warning any loss before occurrence to designated centers are the most effective applications of these systems which can be used in structures in Tehran.