Seismic behavior of reinforced concrete solid slab structures incorporating transfer beam systems

Abstract

This study investigates the seismic behavior of reinforced concrete multi-story buildings incorporating transfer beam systems and floating columns within solid slab configurations. The interaction between transfer beams and slabs plays a critical role in redistributing gravity and seismic loads, influencing both local demands and the global structural response. Although transfer systems are commonly used to meet architectural requirements, they introduce vertical irregularities that significantly affect seismic performance. Unlike previous studies focused on gravity loading or simplified seismic approaches, this research presents an integrated framework combining seismic analysis with Construction Stage Analysis (CSA) for reinforced concrete solid slab systems with transfer beams. A systematic parametric investigation is conducted, examining the effects of beam dimensions, continuity, location, and basement inclusion. A comprehensive numerical analysis is performed using ETABS Ultimate 22.0 for a twelve-story building designed in accordance with the Egyptian Code (ECP 203-2020), utilizing the Egyptian response spectrum for dynamic analysis. The structure is modeled with a concrete compressive strength of 30 MPa and reinforcing steel yield strength of 350 MPa. Equivalent Static Analysis (ESA), Response Spectrum Analysis (RSA), and CSA are employed to evaluate structural performance. Results indicate that CSA provides a more realistic and conservative assessment, with increases of up to 34.77% in bending moments and 28.85% in shear forces compared to RSA. Increasing transfer beam depth significantly reduces deflections by up to 82.79%, while increasing internal force demands. Beam location is critical, where perimeter placement enhances load transfer efficiency, whereas intermediate positions increase lateral displacement by up to 29.44%.