高性能混凝土柱耐火性能之研究

Abstract

隨著時代科技的進步，高性能混凝土具備優越且多樣的性能，已逐漸被重視。但也因其高緻密性的特性，使得其耐火性能較普通混凝土差，而造成使用者在使用上之疑慮。爲推廣此一具備多數優點的混凝土，實有必要對其耐火性能進行研究、了解並改善其缺點。 柱是結構物最重要的構件，因此選定實尺寸柱作為研究對象。本文最終目的是希望能以數值模擬，預測實尺寸柱之耐火時效。而要進行數值模擬分析預測，必先要建立各材料之熱學及各溫度下之力學性質，然後藉由實尺寸柱試驗之結果來驗證數值模擬之可靠性。 基於數值模擬之所需資料，本文進行了下列的研究：高強度混凝土受高溫影響之應力應變曲線試驗、高強度混凝土受高溫影響之軸向變形行為、實尺寸高性能混凝土柱之耐火性能試驗及高性能混凝土耐火時效之數值模擬分析。主要試驗變數包括：骨材種類、纖維加勁、試驗溫度、荷重強度、端點束制條件及偏心載重等變數。 本文研究結果，除了建立高性能混凝土受高溫影響之力學性質，也完成高性能混凝土柱之耐火試驗，並改善了純高性能混凝土之耐火性能，最後提出一數值模擬分析程式，其預測之高性能混凝土柱之耐火時效，具有可供參考之價值。

In recent years, the construction industry has shown significant interest in the use of high performance concrete (HPC). This is due to the improvements in structural performance. However, some studies show, the fire resistance performance of HPC is worse than normal strength concrete (NSC), due to the character of high density. In order to popularize the use of HPC, it is necessary to understand and improved the fire resistance performance of HPC. The final goal of this study is to build up a numerical model, to predict the fire resistance of full-scale column. However, for the use of numerical model, the thermal properties and mechanical properties of materials at elevated temperatures are required. The validity of the numerical model is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. This study, presents the results of the stress-strain curve test of high strength concrete (HSC) at elevated temperatures, the axial deformation of HSC at elevated temperatures, the fire resistance test of full-scale HPC column and the numerical modeling for evaluating the fire resistance of HPC column. The variables include the type of aggregate, reinforcement of fiber, elevated temperature, load density, end condition and eccentric load. The results show that the fire resistance of a NSC column is higher than that of a HPC column. Also, the addition of polypropylene fibers and the use of carbonate aggregate improve the fire resistance. The computer program presented in this study is capable of predicting the fire resistance of HPC columns, with an accuracy that is adequate for practical purpose.