Strain testing reinforced concrete beams
Engineers at the University of Sulaimani are studying the resiliance of reinforced concrete beams, and are using a Windmill data acquisition kit to do so.
The researchers tested the strengthened concrete beams under four-point bending using a hydraulic jack of 800kN capacity. They placed Four steel plates (60mm x 200mm x 20mm) were used under load cells and on the supports to prevent local failure due to stress concentration.
To measure tensile and compressive strength of bars and sheets, they installed three different gauge lengths of strain gauges. They added five Linear Variable Differential Transformers (LVDTs) to measure deflections.
A Windmill Microlink 851 data logger with 594 box (screw terminals with strain measurement), collects data from the load cells, LVDTs and strain gauges. The 851 connects to a computer via either the Internet or Ethernet cables. As well as the load, strain and displacement measurements, it can provide digital inputs and outputs, frequency counting, event counting and other analogue measurements like temperature, pressure, current, flow, level and pH. In all 48 channels are available on each Microlink. Two alarm thresholds may be set on all input channels, and digital channels switched on alarms.
The researchers compared their experimental results to the finite element modelling (FEM) method and found the FEM beam prediction to be stiffer and more robust than they actually were.
Further Reading
Microlink 851 data logger: Data logging, control and real-time data acquisition for Ethernet and Internet
Brwa Hamah Saeed Hamah-Ali ,Mohamed Raouf Abdul Qadir The effect of different levels of pre-damage loading on the strength and structural behavior of CFRP strengthened R.C. beams: Experimental and analytical investigation, PLOS ONE, 2021, https://doi.org/10.1371/journal.pone.0261290
