Design of slender concrete columns using compatibility and equilibrium approach (Dual project)

• Main Author: Ng, Henry Yong Xiang
• Other Authors: Chuang Poon Hwei
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering::Civil engineering::Structures and design
• Online Access: http://hdl.handle.net/10356/67242
• Institution: Nanyang Technological University

The purpose of the project is to evaluate the safety and reliability of the Compatibility and Equilibrium Approach to bring about a quick analysis and prediction of the failure load of reinforced concrete slender columns. Slender columns used in the analysis were taken to be pin-ended and uniaxial loaded allowing only bending in the minor axis. A computer program was developed using C programming language, in accordance to the proposed method, to predict the failure load of the test columns. Failure load from other design approaches such as Transformation approach, American Concrete Institution (ACI 318-2014) and Canadian Standards (CSA 2010) were obtained from various existing programs. To justify the creditability of the proposed compatibility and equilibrium approach, the ratio of the experimental failure load to calculated failure load (N experimental / N calculated) was used as the basis for the comparisons. The ratio of failure load obtained from the 148 test columns were used in an extensive comparison based on the slenderness ratio (L/h) from 10 to 57.69, eccentricity to depth ratio (e/h) from 0.03 to 0.83, compressive concrete strength (fcu) from 19.74 to 112 MPa, steel strength (fy) from 272 to 625 MPa and reinforcement ratio (ρ) from 0.78% to 5.24%. By comparing the ratio of failure loads, it was observed that various design parameters have different effects on the ratio of failure load. Increase in the slenderness ratio, eccentricity to depth ratio and improvement to the material properties such as an increase in the compressive concrete strength and steel strength will cause a decrease in the ratio of failure load. Furthermore, it was found that the slenderness ratio have a smaller effect on the change of the ratio of failure load when the eccentricity to depth ratio becomes higher. When compared to other design approaches, the failure load predicted by the proposed method is the closest to the experimental failure load. As the overall mean ratio of failure load is 1.31 with a coefficient of variation of 32.95%. However, the proposed method overestimates the failure load for slender columns that fail by material failure only, thus additional factor of safety should be considered when such slender columns are designed.