Effect of Anchor Bars on Seismic Behavior of Infilled Walled Frames
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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205
DOI 10.1007/s12205-020-1979-9
Structural Engineering
Effect of Anchor Bars on Seismic Behavior of Infilled Walled Frames Atila Kumbasaroglu
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Dept. of Civil Engineering, Erzincan Binali Yildirim University, Erzincan 24002, Turkey
ARTICLE HISTORY
ABSTRACT
Received 1 November 2019 Revised 10 March 2020 Accepted 25 May 2020 Published Online 5 August 2020
User-defined plastic hinge properties obtained experimentally are used to examine the structural behavior of bare, infilled walled frames with and without anchor bars in reinforced concrete (RC) buildings. Experimentally obtained moment-curvature relationships of structural members (i.e., beams and columns) are used to determine the plastic hinge properties of each section. Three building frames are modeled and examined for time-history analysis using 20 ground-motion records. Seismic performance levels of three buildings are analyzed to determine the effects of anchor bars. Limit states at each performance level are defined, and the multi-record incremental dynamic analysis curves are obtained; 16%, 50%, and 84% fractal curves are obtained for each case. Cumulative distribution functions are constructed to summarize the varieties in the roof-drift ratios of three RC buildings with different frame types for design-based and maximum-considered earthquake hazards. It is found that, with an increased spectral acceleration of ground motions, the probability of exceeding the performance levels of infilled walled frames in reinforced buildings is reduced with the help of anchor bars. The increased stiffness of RC buildings with infilled wall frames exhibiting lower ductility is re-gained by the absorption energy of the anchor bars.
KEYWORDS Infilled walls Anchor bars Incremental dynamic analysis Time-history response IDA curves Roof-drift ratio
1. Introduction Theoretical flexural moment capacity is based on certain loadcarrying assumptions such as plane sections remain planar after bending, the tensile strength of concrete and the effect of transverse reinforcement bars on moment-resisting capacity are neglected. Because the strain hardening of reinforcing steel and confinement effects are neglected, the theoretical flexural moment capacity is less than the actual capacity of structural members. The strength capacities of structural members increase because of such assumptions. Increased member stiffness can cause a reduction in the ductility and energy absorption capacities of reinforced-concrete (RC) buildings under the impact of seismic waves. To increase their ductility, design approaches to reduce earthquake loads as a structural behavior factor are often implemented. Although the structural behavior of infilled walled frames and design approaches to reduce earthquake loads have been specified by many earthquake codes (e.g., EN 1998-1:2005, 2003; Turkish Code [Turkish Ministry of Public Works and Settlement], 2007), the effect of anchor bars on infilled walled frames requires further study. The abso
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