Deformation monitoring of load-bearing reinforced concrete beams

Abstract

Accurate and reliable estimation of the durability and service life of reinforced concrete structures is crucial for predicting and extending their service life. Therefore, we propose a version of the automatic deformation monitoring system deployed to control the reinforced concrete structure, which is an air bridge connecting two parts of the structure. The load-bearing elements of this bridge are the reinforced concrete beams bound together and resting on iron support columns. The deformation monitoring system allows making crack opening measurements and controlling changes in the macroscopic structure parameters (vertical displacement of beam transverse sections). Control of the vertical displacement of beam elements is implemented by means of hydrostatic level and taut string techniques. The system is provided with IP–cameras (sensors), which makes possible the photogrammetric evaluation of crack width and beam vertical displacements (deflections). Based on the estimates obtained from mathematical modeling, the crack opening values corresponding to pre-critical and critical fracture conditions and the appropriate loads are obtained. The accumulated data are used as the basis for assessing the current deformation state of the structure in relation to the obtained estimates and for predicting the evolution of damage and the residual service life of structures. The proposed automatic monitoring system has been successfully used to control the state of the real structure for 2 years. Analysis of the obtained database indicates seasonal changes in the crack width and reveals the tendency of crack opening to increase with time.