鋼筋混凝土樁帽剪力強度之研究

Abstract

鋼筋混凝土樁帽結構普遍運用在建築物與橋樑結構之底部，其主要功能為傳遞結構體上方之載重至土盤。在設計上除了要考慮土壤容許乘載力外，其強度亦須足夠以避免樁帽之破壞。 美國 ACI 規範針對鋼筋混凝土樁帽之強度評估，僅以基礎版尺寸與混凝土強度作為評估，忽略了柱與樁之相互位置與拉力鋼筋之關係。為探討ACI規範不足之處，本研究應用軟化壓拉桿模型，結合開裂點與強度點的概念，得到不同傳力路徑之力量與位移關係，以發展一套評估鋼筋混凝土樁帽版剪力強度之模型。本文建議方法與文獻中既有實驗數據比較，均可得到合理之預測結果。

Reinforced concrete pile caps are commonly used at the bottom of buildings and bridges, and the main function of pile caps is transmitting loadings from the structure to the ground. While designing pile caps, engineers consider not only bearing capacity of soil but also strength of pile caps in order to avoid failure. While evaluating shear strength of reinforced concrete pile caps, ACI code only consider pile caps’ dimensions and concrete strength, ignoring tension steel and relative position of columns and piles. In order to discuss the defects of ACI code and evaluating shear strength of reinforced concrete pile caps, the proposed model in this thesis uses softened strut and tie model and combines the concept of cracking point and strength point, and the force-displacement relation of different load paths can be calculated. Predicting results of shear strength are reasonable while comparing the experimental data with the calculation using the proposed model in this thesis.