Compatibility and equilibrium approach to slender concrete column design (dual project)
Hing, Wee Sheng
Date of Issue2017-05-16
School of Civil and Environmental Engineering
Columns are important structural members for supports in a building. However, there is inadequacy in the experimental data to design a column accurately and sufficiently. A new design method based on the compatibility and equilibrium approach has been proposed. The purpose of this final year project is to study the proposed method and evaluate its function ability and efficiency of predicting failure loads. Comparisons will be done to the proposed method with ACI 314 and BS8110 as these two codes will be more suitable to Singapore environment. The proposed method uses numeric system for its analysis of failure load of a slender column bending about the minor axis, by estimation of the cross section at medium height using moment-deflection curve. The American Concrete Institute code, ACI 318-2014 method mainly follows the concept of using moment magnified method, whereas the British Standard, BS8110 method uses column load moment interaction diagram to determine the failure load. From the results analysis based on experimental and theoretical calculation, a total of 117 columns tested is discussed to evaluate their test results. It is proven from the results analysis that the higher the slenderness ratio, the lower the ratio of failure loads which is N exp / N predicted of different methods. The higher the eccentricity to depth ratio also constitutes to a lower the ratio of failure loads. In contrast, increase of concrete strength increases the ratio of failure loads. The proposed method is a valid method to estimate the failure loads. The overall mean is 1.4765 while the coefficient of variations is 10.85%. It is acceptable as its mean show that it has safety factor. However, proposed method over predicts some of the failure loads, which means more precautions to be taken when designing. Comparatively, BS8110 is the least conservative with a 1.1601 mean and coefficient of variation of 16.21% while ACI is the most conservative overall with a 1.5862 mean and 12.05% coefficient of variation.
Final Year Project (FYP)
Nanyang Technological University