Size effect on punching resistance of thick reinforced concrete flat slabs: numerical analysis and normative predictions

• Grant number: 24/19327-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Alex Micael Dantas de Sousa
• Grantee: Ana Laura Shiraga Araujo
• Host Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

Punching resistance is usually one of the primary checks in the design of reinforced concrete flat slabs, especially in situations where shear reinforcement is unavailable. For slabs thicker than 300 mm, it is observed that there is a significant reduction in nominal shear resistance with increasing slab thickness, also known as the size effect. However, it is observed in the literature that the number of tests that deal with the punching resistance of slabs with greater thicknesses is still relatively limited, mainly due to the difficulties associated with this type of laboratory test. For this reason, it is proposed to develop a numerical study emphasizing the evaluation of the scale effect in reinforced concrete slabs with significant thickness and without transverse reinforcement. For this, it is initially intended to develop a numerical modeling strategy based on the ABAQUS software to represent the failure of flat slabs subject to the size effect. Subsequently, we intend to carry out a parametric study with variations in the compressive strength of the concrete and the reinforcement ratio of the slabs to increase the number of available results related to thicker slabs. Finally, we intend to compare the resistance of the developed numerical models with those predicted by the main normative design codes, including ABNT NBR 6118:2023 and ACI 318:2019. From the proposed study, we expect to identify the level of precision of the different normative codes to address the scale effect in reinforced concrete flat slabs. In addition, we hope that the results can support and assist in future discussions on revising national technical standards.