Estudio del requerimiento de armadura mínima en túneles de hormigón armado sometidos a presión interior y que utilizan hormigones de alta resistencia : modelación numérico computacional que permita comprender la variación de acero mínimo en dovelas prefabricadas de túneles conforme la resistencia del hormigón aumenta.

Abstract

The present work studies the variation of the minimum steel reinforcement in precast tunnel segments as the compressive strength of the concrete increases. The study is realized through numerical simulation with the software ANSYS Workbench 2022 R2 student version. A micro plane damage and plasticity model was used to describe nonlinear behavior of the concrete, while the Dodd-Restreppo model was used for the steel reinforcement. Finite element analysis was carried out on 60 segments with compressive strengths of 50, 60, 70, 80, and 90 MPa and thicknesses of 20, 30, and 40 cm. The minimum amount of flexural reinforcement was calculated using the equations of Eurocode, ACI-318, and Hesham Marzouk. A dimensional analysis criterion was proposed for validation based on stress-strain curves, which shows that the transition of stresses from concrete to steel is smooth. The results show that the minimum steel amount is directly proportional to compressive strength, but inversely proportional to height of the element. ACI-318 overestimates the minimum reinforcement ratio, while Eurocode underestimates the minimum steel. The criteria of Hesham Marzouk are appropriate and applicable to calculate the minimum steel in segments. Finally, based on the conclusions obtained, a chart is proposed to obtain the minimum steel quantity in flexural segments.