Updating the bearing capacity, stresses, and strain for retrofitting reinforced concrete towers of the cellular and internet system

Abstract

To retrofit reinforced concrete telecommunication towers, it is necessary to update their parameters because the structure’s bearing capacity is no longer the same as at the initial moment of commissioning. Reinforced concrete columns are elements formed from the combination of two materials—steel and concrete—making them a composite material. For the calculation of induced stresses in sections of composite materials, homogenization techniques are required. Due to the slow deformation of the concrete, as a function of the rheological behavior of the material, some of the stresses that were absorbed by the homogenized concrete section are transferred to the reinforcement, causing an increase in the initially calculated values. To evaluate the stress in the reinforcement and the structural strain, an analytical mathematical procedure with nonlinear characteristics was employed to investigate a real, slender, reinforced concrete column, for which the critical buckling load was dynamically determined. A variation of loading considering the column exclusively under its self-weight up to the imminence of instability was applied. Then, by computing the equilibrium of forces and compatibility displacements, allied to the criteria for creep, shrinkage and strength of concrete present in the European Standard EN 1992‐1‐1, Eurocode 2, it was possible to verify that the induced stresses in the reinforcement steel do not produce the material yielding so that strain does not initiate the cracking process in the concrete.

Keywords:

• Retrofitting
• reinforced concrete structures
• stresses
• strain
• rheology
• bearing capacity