ABSTRACT
This chapter describes the characteristics, functions and installations of the most commonly used sensors, categorised according to the monitoring quantities. Sensors are one of the most critical components of a smart civil structure since the smart performance depends on the quality of the data collected. The traditional sensors widely used to measure wind speed and direction at the site of a smart civil structure are propeller and ultrasonic anemometers. The accuracy of the anemometers in measuring wind velocity must be maintained under heavy rain; that is, there should be no occurrence of spikes during heavy rainstorms. Wind pressure transducers sense differential pressure and convert this pressure difference into a proportional electrical output for either unidirectional or bidirectional pressure ranges. In mono-static systems, the atmospheric scattering is caused by temperature fluctuations, whereas in bi-static systems such scattering is caused by both temperature and wind velocity fluctuations.
