Simplified model for pre-code RC column exposed to fire followed by earthquake.

Area of Science:

• Structural Engineering
• Materials Science
• Fire Safety Engineering

Background:

• The behavior of reinforced concrete (RC) columns after fire exposure and subsequent seismic loading is poorly understood.
• This knowledge gap is critical for assessing the safety of existing buildings that have experienced fire and may face seismic events without adequate repair.
• Pre-code RC columns, often lacking seismic design considerations, are particularly vulnerable.

Purpose of the Study:

• To develop a simplified modeling framework for assessing the post-fire cyclic behavior of RC columns.
• To create and validate simplified material models for confined concrete, focusing on its performance after fire exposure.
• To evaluate the effectiveness of the proposed model against experimental data.

Main Methods:

• Development of simplified material models for confined concrete, considering post-fire conditions.
• Validation of the proposed model using experimental results from a non-seismically designed RC column.
• Simulation of three scenarios: cyclic loading only, cyclic loading after 30-minute fire exposure, and cyclic loading after 90-minute fire exposure.

Main Results:

• Simplified material models can accurately represent the post-fire cyclic behavior of non-seismically designed RC columns.
• The choice of confined concrete model significantly influences the column's performance after reaching peak strength.
• Fire exposure duration (30 vs. 90 minutes) impacts the post-fire cyclic response.

Conclusions:

• The proposed simplified modeling framework is effective for evaluating the seismic performance of RC columns after fire exposure.
• Accurate material modeling of confined concrete is essential for predicting post-fire structural behavior.
• The study provides valuable insights for the assessment and retrofitting of fire-damaged structures.