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.

摘要

改造钢筋混凝土通信铁塔时，由于结构承载力已不再与投运初期相同，因此需要更新其参数。钢筋混凝土柱是由两种材料（钢和混凝土）组合而成的元素，使它们成为一种复合材料。为了计算复合材料截面中的诱导应力，需要均质化技术。由于混凝土的缓慢变形，作为材料流变行为的函数，均质混凝土部分吸收的一些应力转移到钢筋上，导致初始计算值增加。为了评估钢筋中的应力和结构应变，采用具有非线性特征的分析数学程序来研究真实的细长钢筋混凝土柱，动态确定其临界屈曲载荷。应用了仅在其自重下直至即将发生不稳定的情况下考虑该柱的载荷变化。然后，通过计算力和相容位移的平衡，结合欧洲标准 EN 1992-1-1，欧洲规范 2 中混凝土的徐变、收缩和强度标准，可以验证在钢筋不会产生材料屈服，因此应变不会引发混凝土开裂过程。其中临界屈曲载荷是动态确定的。应用了仅在其自重下直至即将发生不稳定的情况下考虑该柱的载荷变化。然后，通过计算力和相容位移的平衡，结合欧洲标准 EN 1992-1-1，欧洲规范 2 中混凝土的徐变、收缩和强度标准，可以验证在钢筋不会产生材料屈服，因此应变不会引发混凝土开裂过程。其中临界屈曲载荷是动态确定的。应用了仅在其自重下直至即将发生不稳定的情况下考虑该柱的载荷变化。然后，通过计算力和相容位移的平衡，结合欧洲标准 EN 1992-1-1，欧洲规范 2 中混凝土的徐变、收缩和强度标准，可以验证在钢筋不会产生材料屈服，因此应变不会引发混凝土开裂过程。