Evaluation of Reduction Factors for Vertically Irregular RC Frames: Conventional vs. Adaptive Pushover Analysis | ||
| JES. Journal of Engineering Sciences | ||
| Article 1, Volume 54, Issue 2, March and April 2026 PDF (1.2 M) | ||
| Document Type: Research Paper | ||
| DOI: 10.21608/jesaun.2025.412513.1673 | ||
| Authors | ||
| M. Assem Soliman* 1; Mohamed Abdelshakor Hasan1; Hossameldeen M Mohamed2; Shehata E Abdel Raheem3 | ||
| 1Construction and Building Department, The Arab Academy for Science Technology and Maritime Transport Aswan Brach, Aswan, Egypt. | ||
| 2Civil Engineering Dept., Faculty of Engineering, Aswan University, Aswan, Egypt. | ||
| 3Civil Engineering Dept., Faculty of Engineering, Assiut University, Assiut, Egypt. | ||
| Abstract | ||
| The significant computational demand of Nonlinear Time-History Analysis (NTHA) often leads seismic design practitioners to opt for the more efficient Nonlinear Static Pushover Analysis. However, conventional pushover methods, typically reliant on the first-mode pattern, fail to capture the significant influence of higher modes. This limitation becomes particularly critical in vertically irregular structures, where geometric discontinuities can amplify higher-mode effects, leading to an inaccurate assessment of seismic performance. This study addresses this gap by employing Displacement-Based Adaptive Pushover Analysis (DAP) to account for these higher-mode effects. We investigated five distinct configurations of vertically irregular reinforced concrete (RC) moment-resisting frames to evaluate and compare the seismic reduction factors derived from both conventional Static pushover analysis first mode pattern CSPA and DAP, benchmarking these results against the prescribed limits in Eurocode 8. The findings are compelling: geometric irregularities located near the base of the structure lead to a substantial discrepancy between the reduction factors calculated by DAP and CSPA. Critically, the adaptive analysis consistently yielded significantly lower and more conservative reduction factors, which frequently fell below the code's minimum values. This result suggests that current code provisions may dangerously overestimate the seismic capacity and ductility of such structures, masking their true vulnerability. The study concludes that for vertically irregular frames, particularly those with significant discontinuities in lower stories, adaptive pushover analysis is a necessity for achieving a safe and realistic seismic performance assessment. | ||
| Keywords | ||
| Reinforced Concrete Moment-Resisting Frames (RC MRFs); Vertical Irregularities; Eurocode 8; Reduction Factor; Displacement-Based Adaptive Pushover Analysis (DAP) | ||
| References | ||
|
[1] H. AbdelMalek, T. K. Hassan, and A. Moustafa, “Nonlinear time history analysis evaluation of optimized design for medium to high rise buildings using performance-based design,” Ain Shams Engineering Journal, vol. 14, no. 9, p. 102081, Sep. 2023, Doi: 10.1016/J.ASEJ.2022.102081.
[2] H. Krawinkler and G. D. P. K. Seneviratna, “Pros and cons of a pushover analysis of seismic performance evaluation,” Eng Struct, vol. 20, no. 4–6, pp. 452–464, Apr. 1998, Doi: 10.1016/S0141-0296(97)00092-8.
[3] R. S. Lawson, V. Vance, and H. Krawinkler, “Nonlinear Static Push-Over Analysis-Why, When, and How?,” in earthquake engineering, US NATIONAL CONFERENCE ON EARTHQUAKE ENGINEERING, EERI; , 1994, pp. 283–292. [Online]. Available: https://www.tib.eu/de/suchen/id/BLCP%3ACN006569780
[4] J. C. Reyes, A. C. Riaño, E. Kalkan, and C. M. Arango, “Extending modal pushover-based scaling procedure for nonlinear response history analysis of multi-story unsymmetric-plan buildings,” Eng Struct, vol. 88, pp. 125–137, Apr. 2015, Doi: 10.1016/J.ENGSTRUCT.2015.01.041.
[5] A. Feizolahbeigi and N. Mendes, “Evaluation of different types of advanced analysis for the study of the seismic behavior of masonry minarets,” Structures, vol. 78, 2025, Doi: 10.1016/j.istruc.2025.109134.
[6] Eurocode 8 - Design of structures for earthquake resistance - Part 5: Geotechnical aspects, foundations, retaining and underground structures”.
[7] American Society of Civil Engineers, Minimum Design Loads and Associated Criteria for Buildings and Other Structures. Reston, VA: American Society of Civil Engineers. Doi: 10.1061/9780784414248.
[8] F. Rofooei, F. R. Rofooei, N. K. Attari, A. Rasekh, and A. H. Shodja, “Adaptive pushover analysis,” 2007. [Online]. Available: https://www.researchgate.net/publication/261362924
[9] K. Shakeri, K. Tarbali, and M. Mohebbi, “An adaptive modal pushover procedure for asymmetric-plan buildings,” Eng Struct, vol. 36, 2012, Doi: 10.1016/j.engstruct.2011.11.032.
[10] S. Antoniou and R. Pinho, “Development and verification of a displacement-based adaptive pushover procedure,” Journal of Earthquake Engineering, vol. 8, no. 5, pp. 643–661, 2004, Doi: 10.1080/13632460409350504.
[11] S. T. Antoniou and R. Pinho, “Development and verification of a displacement-based adaptive pushover procedure,” Journal of Earthquake Engineering, vol. 8, 2004, Doi: 10.1142/S136324690400150X.
[12] R. Pinho, “A displacement-based adaptive pushover algorithm for assessment of vertically irregular frames,” 2005. [Online]. Available: https://www.researchgate.net/publication/255650505
[13] R. Pinho, “A Displacement-Based Adaptive Pushover Algorithm for Assessment of Vertically Irregular Frames.” 4th European Workshop on the Seismic Behavior of Irregular and Complex Structure, Thessaloniki, Greece.
[14] Albert, D. Christianto, and H. Pranata, “Seismic evaluation of buildings using adaptive force-based multimode pushover analysis,” IOP Conf Ser Mater Sci Eng, vol. 1007, 2020, Doi: 10.1088/1757-899X/1007/1/012098.
[15] M. Jalilkhani, S. H. Ghasemi, and M. Danesh, “A multi-mode adaptive pushover analysis procedure for estimating the seismic demands of RC moment-resisting frames,” Eng Struct, vol. 213, p. 110528, Jun. 2020, Doi: 10.1016/J.ENGSTRUCT.2020.110528.
[16] D. Soni, J. Prajapati, and R. Sheth, “Comparative study of nonlinear static pushover analysis and displacement based adaptive pushover analysis method,” International Journal of Structural Engineering, vol. 9, no. 1, p. 1, 2018, Doi: 10.1504/ijstructe.2018.10009092.
[17] IS 1893 (Part 1):2016, Criteria for Earthquake Resistant Design of Structures, Part 1: General Provisions and Buildings.
[18] “ECP-201, Egyptian Code for Calculating Loads and Forces in Structural Work and Masonry”.
[19] A. M. MWAFY and A. S. ELNASHAI, “Calibration of Force Reduction Factors of Rc Buildings,” Journal of Earthquake Engineering, vol. 6, no. 2, pp. 239–273, Apr. 2002, Doi: 10.1080/13632460209350416.
[20] H. Abou-Elfath and E. Elhout, “Evaluating the Response Modification Factors of RC Frames Designed with Different Geometric Configurations,” International Journal of Civil Engineering, vol. 16, no. 12, pp. 1699–1711, 2018, Doi: 10.1007/s40999-018-0322-z.
[21] M. Issa, H. Issa, M. S. Issa, and H. M. Issa, “Application of Pushover Analysis for the calculation of Behavior Factor for Reinforced Concrete Moment-Resisting Frames,” INTERNATIONAL JOURNAL OF CIVIL AND STRUCTURAL ENGINEERING, vol. 5, no. 3, 2015, Doi: 10.6088/ijcser.2014050021.
[22] S. E. Abdel Raheem, M. M. M. Ahmed, M. M. Ahmed, and A. G. A. Abdel-Shafy, “Seismic performance of L-shaped multi-storey buildings with moment-resisting frames,” Proceedings of the Institution of Civil Engineers - Structures and Buildings, vol. 171, no. 5, pp. 395–408, May 2018, Doi: 10.1680/jstbu.16.00122.
[23] S. E. Abdel Raheem, M. M. M. Ahmed, M. M. Ahmed, and A. G. A. Abdel-shafy, “Evaluation of plan configuration irregularity effects on seismic response demands of L-shaped MRF buildings,” Bulletin of Earthquake Engineering, vol. 16, no. 9, pp. 3845–3869, Sep. 2018, Doi: 10.1007/s10518-018-0319-7.
[24] A. M. Abdelalim, Y. Shalaby, G. A. Ebrahim, and M. Badawy, “Applying Fuzzy Decision-Making and Markov Chain Modelling for Detecting Life Cycle of RC Bridges,” Journal of Engineering Sciences, vol. 53, no. 6, pp. 274–309, Nov. 2025, Doi: 10.21608/jesaun.2025.390430.1534.
[25] T. M. Abdelaleleem, M. Elsayed, H. M. Diab, and Y. A. Hassanean, “Proposed Shear Design Method for Continuous Reinforced Concrete Beams Considering Moment Redistribution,” JES. Journal of Engineering Sciences, vol. 0, no. 0, pp. 0–0, Aug. 2025, Doi: 10.21608/jesaun.2025.376890.1483.
[26] D. Santos, J. Melo, and H. Varum, “Comparative Analysis of the Impact of Vertical Irregularities on Reinforced Concrete Moment-Resisting Frame Structures According to Eurocode 8,” Buildings, vol. 14, no. 9, Sep. 2024, Doi: 10.3390/buildings14092982.
[27] D. C.: B. S. S. C. FEMA. NEHRP Guidelines for Seismic Rehabilitation of Buildings. Washington, FEMA-273. (1997). 1997.
[28] B. Andrew Whittaker, G. Hart, and C. Rojahn, “SEISMIC RESPONSE MODIFICATION FACTORS,” 1999.
[29] A. R. Kemp, “Simplified amplification factors representing material and geometric inelasticity in frame instability,” Eng. Struct., vol. 22, 2000, Doi: 10.1016/S0141-0296(00)00002-X.
[30] C.-M. Uang and A. Member, “establishing R (or Rw) and Cd factors for building seismic provisions.” Journal of Structural Engineering 117(1), January 1991. DOI: 10.1061/(ASCE)0733-9445(1991)117:1(19)
[31] M. M. M. Ahmed, M. Abdo, and W. A. E.-W. Mohamed, “Evaluation of Seismic Response Modification Factor (R) for Moderate-Rise RC Buildings with Vertical Irregular Configurations,” 2021. https://api.semanticscholar.org/CorpusID:245113943
[32] M. Menegotto and P. E. Pinto, “Method of Analysis for Cyclically Loaded R.C. Plane Frames Including Changes in Geometry and Non-Elastic Behavior of Elements under Combined Normal Force and Bending Untersuchungsmethode für zyklisch belastete ebene Stahlbeton-Rahmen einschliesslich der Geometrie-Änderungen und des nicht-elastischen Verhaltens von Elementen unter zusammengesetzten Axial-und Biegungskräften.”
[33] A. Prota, F. de Cicco, and E. Cosenza, “Cyclic Behavior of Smooth Steel Reinforcing Bars: Experimental Analysis and Modeling Issues,” Journal of Earthquake Engineering, vol. 13, no. 4, pp. 500–519, May 2009, Doi: 10.1080/13632460902837686.
[34] SeismoStruc, “https://seismosoft.com/product/seismostruct/,” 2025.
[35] F. Filippou, “Nonlinear Analysis of Reinforced Concrete Frames Under Cyclic Load Reversals”. (EERC Report 88-12. 1988).
[36] European Committee for Standardization, “EN 1998-1; Eurocode 8: Design of Structures for Earthquake Resistance—Part 1: General Rules, Seismic Actions and Rules for Buildings. European Committee for Standardization: Brussels, Belgium, 2005.” | ||
|
Statistics Article View: 196 PDF Download: 47 |
||
