Integrated stress measurement system in tower crane mast

In the paper two methods for measuring changes in stress for slender steel structure are presented. The first method consists of surveying the inclination of the tower mast and jib by using a tacheometer to measure the coordinates of two prisms placed on the construction crane. The measurement of these deflections performed with a simple model of endurance allowed to calculate stresses in the base of the mast crane. The stresses resulted from changing load by transferring construction parts on its arm. The redundant measurement system which was used during measurements is called a Self-excited Acoustical System (SAS). Due to the self-oscillation effect it was possible to measure the changes in stress at the lift mast base. During the process of measurement two self-excited loops were used to allow stress monitoring in all corners of the truss crane construction. This article presents a comparison of the results obtained by two parallel measurement systems and analyzes the possibility of integrating them into a single, redundant system for measuring stress changes.