Performance-Based Seismic Analysis of Flat Slab Buildings with Lateral Resistance

Abstract

Flat slab structural systems are increasingly adopted in modern multistorey buildings due to their architectural flexibility, reduced construction time, and economical formwork. However, the absence of beams leads to reduced lateral stiffness, making flat slab structures vulnerable under seismic loading. This study presents a detailed survey and analytical investigation on the seismic behavior of flat slab buildings, emphasizing the role of lateral load resisting systems such as shear walls and bracing. A nonlinear static pushover analysis approach is adopted to evaluate structural performance under seismic actions. The study reviews existing literature, identifies research gaps, and proposes a systematic methodology using ETABS for modelling , hinge assignment, and performance evaluation. Key seismic response parameters such as base shear, roof displacement, storey drift, and hinge formation patterns are analyzed. The findings highlight the effectiveness of lateral load resisting systems in enhancing the seismic performance of flat slab structures and provide insights for future research directions.

Introduction

Flat slab structures are reinforced concrete slabs supported directly by columns, eliminating beams. They offer reduced floor height, architectural flexibility, easier formwork, and faster construction, making them common in commercial, residential, and parking buildings.

Seismic Vulnerabilities:

• Low lateral stiffness and ductility due to absence of beams.

• Susceptible to excessive lateral displacement, punching shear at slab–column joints, and progressive collapse during earthquakes.

• Historical seismic events have highlighted poor performance without lateral load resisting systems.

Mitigation Approaches:

• Shear walls, braced frames, and core walls are introduced to enhance stiffness, strength, and energy dissipation.

• Traditional linear elastic analyses often fail to capture nonlinear behavior during strong ground motions.

Nonlinear Pushover Analysis:

• Simulates progressive damage and plastic hinge formation.

• Evaluates base shear capacity, roof displacement, storey drift, capacity curves, and hinge patterns.

• Helps assess Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP) performance levels.

Literature Insights:

• Flat slab buildings without lateral resistance show excessive drift and premature punching shear failures.

• Shear walls, especially centrally located, significantly improve seismic performance by increasing lateral capacity and delaying plastic hinge formation.

• Bracing systems improve stiffness but effectiveness depends on configuration, material, and connections.

• Most prior studies used linear analysis; nonlinear, performance-based evaluations are limited.

Proposed Methodology:

1. Structural Modeling: ETABS models of multistorey flat slabs with (i) no lateral system, (ii) shear walls, (iii) bracing systems.

2. Load Assignment: Dead, live, and seismic loads per IS 875 and IS 1893.

3. Nonlinear Hinges: Defined for columns and shear walls per FEMA/ATC guidelines.

4. Pushover Analysis: Incremental lateral load application until target displacement or instability; capacity curves generated.

5. Performance Evaluation: Comparison of base shear, roof displacement, storey drift, and hinge formation to identify IO, LS, and CP levels across configurations.

The study provides a systematic framework to assess and compare the seismic performance of flat slab structures with different lateral load resisting systems, bridging gaps in nonlinear performance evaluation.

Conclusion

This study research provides a detailed survey and analytical assessment of flat slab structures subjected to seismic loading through nonlinear pushover analysis. The literature review identifies the inherent seismic deficiencies of flat slab systems and underscores the critical need for effective lateral load resisting mechanisms. The adopted methodology offers a robust framework for performance-based seismic evaluation. The analytical results demonstrate that the inclusion of shear walls and bracing systems significantly enhances seismic performance by increasing base shear capacity, reducing roof displacement, limiting storey drift, and delaying plastic hinge development. Among the evaluated systems, shear walls exhibit superior stiffness and overall structural stability. Furthermore, the comparative study of various structural configurations provides practical guidance for engineers in selecting appropriate lateral load resisting systems at the design stage. The outcomes reinforce the relevance of nonlinear pushover analysis in capturing damage progression and structural capacity, thereby supporting performance-based design approaches. Future investigations may extend this work through nonlinear time-history analysis, consideration of soil–structure interaction, and experimental validation to further improve the seismic resilience of flat slab buildings.

References

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Copyright

Copyright © 2026 V. M. Khanapure, Prof. P. A. Vedpathak, Dr. V. S. Rajamanya. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.