the reliability of load cells in geotechnical science

the reliability of load cells in geotechnical science

strain gauges and load cells are often used to measure strain and load in concrete or steel components of geotechnical structures. reliability problems are frequently cited for these instruments. the purposes of this paper are (a) to discuss the factors that affect the reliability of strain gauges and load cells used for geotechnical engineering applications, (b) to suggest the instrument types that have historically performed most reliably and are therefore preferred by some engineers, (c) to indicate which instruments should prove to be the best choice for future projects, and (d) to establish realistic survivability rates to be used in planning instrumentation programs.

these objectives were accomplished by searching published literature and by surveying the opinions of more than 4o knowledgeable geotechnical engineers. the results of the survey as well as published information have been compiled and are included in the paper. the primary considerations for instrument reliability are instrument characteristics and selection. other considerations include proper planning of the instrumentation program, ability of the instrument to perform the intended function, and field installation and handling techniques. vibrating wire strain gauges are generally preferred for reliable strain measurement. electrical resistance strain gauged load cells are generally preferred for reliable load measurement. planning of an instrumentation program should anticipate the probability that one-quarter to one-half of the instruments may not survive installation or the period of monitoring.