本研究探討不同斷面尺寸之高強度混凝土構件受火害後之溫度分布，並回歸建立慣性矩折減公式，以利工程師於不同火災情境與持續時間下，迅速評估高強度混凝土柱、梁之慣性矩折減情形，進而評估結構耐震性能之損失。
火害後慣性矩修正係數由有限元素分析軟體Abaqus進行熱傳分析求得，且為驗證分析結果之準確性與適用性，先利用《建築結構火害後殘留耐震能力評估手冊》中F70試體之熱偶計數據完成高強度混凝土熱傳分析驗證，並參考林峻立的熱偶計資料及Eurocode 2提供之溫度分布圖，進行一般強度混凝土之熱傳分析比對。
本研究探討700°C、600°C、500°C、400°C四種等溫線法，求得四種方法相對應之火害後慣性矩修正係數後，乘上ETABS靜力分析所得之勁度折減係數，計算出慣性矩折減係數。強度折減係數則依Eurocode 2之表格內插求得。
完成兩種折減係數推估後，利用TEASPA與ETABS進行火害後高強度混凝土柱之非線性靜力側推分析，並以F70試體側推曲線驗證結果，確認600°C等溫線法最適用於高強度混凝土之折減評估。
最後，以TEASPA與ETABS模擬台北一區某14層建築物，在一樓火災條件下進行局部（角落、半區域）及全面火害模擬，火害延時為一小時。疊合側推容量曲線及耐震性能曲線觀察可知，不論火害範圍為何，建物結構性能衰減差異不大，主要因為本案梁柱斷面尺寸大、火害時間短，導致慣性矩及強度折減係數皆接近1（近乎無折減）。其中，一樓柱斷面尺寸130×130 cm，在600°C等溫線下，受損範圍甚至未及保護層一半厚度，驗證了熱傳分析時所得「斷面愈大，慣性矩折減愈小」之結論。

This study investigates the temperature distribution of high-strength concrete members with various cross-sectional dimensions after fire exposure and establishes regression-based formulas for the reduction of moment of inertia. These formulas enable engineers to quickly assess the degree of reduction in the moment of inertia of high-strength concrete columns and beams under different fire scenarios and durations, facilitating the evaluation of post-fire seismic performance loss.
The post-fire moment of inertia correction factors were obtained through heat transfer analysis using the finite element software Abaqus. To verify the accuracy and applicability of the analysis results, thermocouple data from the F70 specimen provided in the "Post-Fire Seismic Capacity Evaluation Manual for Building Structures" were used to validate the heat transfer analysis for high-strength concrete. Additionally, thermocouple data from Lin Jun-Li and temperature distribution graphs from Eurocode 2 were referenced for comparison with normal-strength concrete.
This study examined four isothermal contour methods at 700°C, 600°C, 500°C, and 400°C to determine the corresponding post-fire moment of inertia correction factors. These factors were then multiplied by the stiffness reduction factors obtained from ETABS static analysis to calculate the final moment of inertia reduction coefficients. Strength reduction coefficients were interpolated based on the tables provided in Eurocode 2.
After determining both reduction coefficients, nonlinear static pushover analyses of fire-damaged high-strength concrete columns were performed using TEASPA and ETABS. The results were validated by comparing the pushover curves of the F70 specimen, confirming that the 600°C isothermal contour method was the most suitable for high-strength concrete.
Finally, a 14-story building located in Taipei was modeled using TEASPA and ETABS, simulating partial (corner and half-floor) and full-floor fire scenarios at the first floor, considering a fire exposure duration of one hour. From the overlaid pushover capacity curves and seismic performance curves, it was observed that the structural performance degradation was minor regardless of the fire extent. This is attributed to the large cross-sectional dimensions of the beams and columns and the relatively short fire duration, resulting in moments of inertia and strength reduction coefficients approaching 1 (i.e., almost no reduction). Notably, for the largest column cross-section of 130×130 cm, the 600°C isothermal contour penetration did not even reach half of the protective layer thickness, further validating the conclusion derived from the heat transfer analysis: the larger the cross-section, the smaller the reduction in moment of inertia under the same fire exposure duration.

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