Features of measuring deformations of load-bearing structures of buildings during their field and laboratory tests under the action of static and dynamic loads

Abstract

The peculiarities of measuring the deformations of load-bearing structures of buildings during their field and laboratory tests using strain gauge-based sensors are considered. An overview of various problematic issues that arise in the process of conducting experimental tests and affect the measurement results is given. The most common, which affect the accuracy of measurements, are the effects of temperature, humidity, and vibration; the difficulty of calibrating and mounting strain gauges on different surfaces of elements; complexity of measurement data processing; combination of high-quality work of strain gauges, cable conductors, measuring equipment, data collection and processing system; the selection of the connection scheme of tensor resistors in the Wheatstone bridge. The peculiarities of the organization of the experiment for testing the load-bearing structures of the building, namely pile foundations, are considered, and the main problematic issues when using strain gauges as strain gauges of building elements are given. The use of strain gauges to measure deformations of load-bearing structures of buildings is one of the common methods, which has many advantages, which are discussed in detail in the work. Strain gauges can be used to measure deformations of elements that are mechanically connected to them. They have high measurement accuracy, sensitivity to element deformation, and a wide variable measurement range. The advantages of using the Wheatstone bridge to measure the change in electrical resistance are highlighted, as this method allows measuring very small values of the change in resistance. Methods of connecting tensor resistors according to the Wheatstone scheme are considered, the choice of which depends on the purpose of the study and the required accuracy. One of the easiest ways is to connect just one strain gauge to a current or voltage source and measure the change in resistance. But this method has low sensitivity and does not compensate for the effect of temperature. A more accurate way is to connect two or four tensor resistors in the Wheatstone bridge circuit, which allows you to measure the voltage change on the diagonal of the bridge. The bridge circuit has a high sensitivity and can compensate for the effect of temperature if the tensor resistors have the same coefficient of temperature dependence of the resistance. An algorithm for measuring the deformations of a metal pipe working under compression using strain gauges has been developed.