비선형 유한요소해석을 통한 PC 보강재가 삽입된 슬래브 계면의 균열각 변화에 따른 뚫림전단강도 평가

초록

Flat-plate structures without beams are vulnerable to punching shear due to stress concentrations at slab–column connections. Current design codes assume a constant 45° crack angle and uniform concrete, which may not accurately capture the behavior of slabs with high-strength precast concrete (PC) near the column. This study evaluates punching shear strength by considering crack angle variation at the PC–cast-in-place (CIP) interface using a nonlinear finite element model validated against experimental data. Parametric analyses varied the compressive strength, PC head width, and flexural reinforcement ratio, revealing increased punching shear strength with all parameters. Observed crack angles ranged from 16° to 50°, deviating from the 45° assumption. Comparisons with ACI 318-19 and KDS 14 20 indicate that these codes may misestimate strength under composite slab behavior. The study consequently highlights the need to redefine the critical section to account for material discontinuity and PC head geometry, providing a basis for improved design of hybrid flat-plate systems.

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