Investigation of Effective Flexural Stiffness of Reinforced Concrete Beams

Saeid Foroughi¹ Süleyman Bahadır Yüksel²

1) PhD student in Civil Engineering , Konya Technical University / Turkey
2) Professor of Civil Engineering , Konya Technical University / Turkey

Publication : 7th.International Congress On Civil Engineering, Architecture & Urban Development(7icsau.com)
Abstract :
In determining the seismic performance of reinforced concrete (RC) structures in national and international earthquake regulations, it is desired to use effective section stiffness of the cracked section in RC structural elements during the design phase. Although the effective section stiffness of the cracked section is not constant, it depends on parameters such as the concrete strength and reinforcement ratio. In this study, RC beam models with different concrete strength, tensile and compression reinforcement ratios were designed to investigate nonlinear moment-curvature relationships and effective stiffness coefficients. Analytically investigated parameters were calculated from TBEC (2018), ACI318 (2014), ASCE/SEI41 (2017), Eurocode2 (2004) and Eurocode8 (2004, 2005) regulations and moment-curvature relationships. For the moment-curvature relationships, the SAP2000 software was used by considering different design parameters. The effective section stiffness coefficient obtained from the analyzes were compared with the effective section stiffness coefficient given for RC members in different regulations. The analysis results obtained for different RC beam models are examined by summarizing in graphs and tables. The results obtained at the end were examined by comparing them according to different parameters and models. For constant concrete strength and tensile reinforcement ratio in RC beams, with increasing compression reinforcement ratio, effective stiffness coefficient values increase. In RC beams with constant compression and tensile strength ratio, effective stiffness coefficient values increase with increasing concrete strength. The compression reinforcement ratio has been proved to be effective on the maximum moment bearing capacity of the RC beams, effective flexural stiffness and effective stiffness coefficient and ductility of the sections.
Keywords : Seismic performance; Effective stiffness; Moment-curvature; Structural elements; RC beam.