Numerical Investigation of Anti-Floating Punching Failure and Reinforcement Methods for Basement Slabs in High-Rise Structures

The anti-floating punching failure of basement slabs subjected to groundwater uplift remains insufficiently understood due to the complex stress state and lack of applicable design guidance. This study investigates the punching behavior of a damaged basement slab in Shenzhen, China, using a three-dimensional finite element model developed in LS-DYNA with the Concrete Damage Plasticity (CDP) model. The model was validated against field observations and experimental data, with a prediction error of less than 8%. The results show that anti-floating punching failure evolves from crack initiation in the anchorage zone to damage propagation and final penetration. Increasing the slab thickness from 400 mm to 600 mm significantly alleviated tensile damage concentration and improved stress redistribution. Increasing the concrete compressive strength from 20 MPa to 60 MPa enhanced punching resistance and delayed crack development, but promoted localized brittle failure. Enlarging the foundation pad from CT-6 to CT-9 effectively reduced stress concentration and improved the overall anti-punching performance, whereas the influence of column size was limited. A comparative assessment of three reinforcement measures further revealed their respective applicability under different engineering conditions. The study clarifies the anti-floating punching mechanism of basement slabs and provides a theoretical basis for the anti-floating design and reinforcement optimization of underground structures.