PLASTIC BUCKLING ANALYSIS OF CONVENTIONAL CONCRETE AND EXPANDED POLYSTYRENE CONCRETE SPHERICAL SHELLS

Introduction: Concrete’s self-weight is the primary factor contributing to increased cross-sectional dimensions and dead loads in structures. This disadvantage can be mitigated by using suitable lightweight concrete. Expanded polystyrene concrete (EPSC), which is lighter than conventional concrete, has not yet been implemented in shell structures. The purpose of the study was to analyze and compare the plastic buckling capacities of conventional concrete and EPSC domes, and to develop an analytical formula for determining the plastic buckling capacity of spherical shells made from these materials. The methodology includes an experimental investigation involving cube test specimens to evaluate the properties of EPSC. Based on the test results, the compressive strength, density, and elastic modulus of EPSC were found to be 9.48 MPa, 2074.17 kg/m3, and 11.18 GPa, respectively. Subsequently, linear buckling analysis (LBA) and material non-linear analysis (MNA) were performed using ABAQUS to determine the elastic and plastic buckling resistances of 36 concrete and 36 EPSC spherical shells. Based on the analysis results, an analytical formula was developed to estimate the plastic buckling capacities of both concrete and EPSC shells. Results: The findings reveal that the plastic buckling resistance of EPSC shells is significantly higher than practically applied external uniform pressures. However, the plastic buckling resistance of EPSC shells is lower than that of equivalent concrete shells. Despite this, EPSC shells exhibit lower plastic deformations and displacements compared to their concrete counterparts, indicating sufficient stiffness of such shells and supporting EPSC use in spherical shell construction. The proposed formula can be easily applied to determine the reference plastic buckling capacities of concrete and EPSC spherical shells.