Compatability and equilibrium approach to slender concrete column design (dual project)

Abstract

This report evaluates and compares the proposed design method with the Australian code AS3600-2001 for slender concrete column. The failure loads of pin-end columns under short term loading and uniaxial bending are used as a pre-determined factor to analyse the data.

The report’s purpose is to study the behaviour of slender concrete column’s structural capacity. and the influence of important factors of columns designs such as eccentricity ratio (e/h), slenderness ratio (L/h), steel reinforcement ratio, concrete strength (fcu) and reinforcement strength (fy).

C+ programming codes and hand calculations on 150 columns with slenderness ratio of between 33 to 133, and load eccentricity ratio from 0.033 to 0.83, reinforcement percentage ratio between 0.77% to 4.21% and concrete strength from 19.77 to 106.79 Mpa and steel yield strength from 271 to 532 Mpa.

The analysis and results shows that the general trend is that the predicted load will decrease when the eccentricity ratio (e/h) and slenderness ratio (L/h) increases. The predicted load will increase when concrete strength (fcu) and the steel reinforcement ratio increases.

The analysis of the proposed design method with the Australian code AS3600-2001 is the main focus of the paper. However, different methods like the P-delta method, British Code BS8110 and Eurocode EC2 is also used as a base comparison to both the proposed design method and the AS3600-2001. The predicted failure load is divided by the actual experimental failure load (Pproposed/Pexp).

In general comparison of the 4 critical parameters stated, the Australian code AS3600-2001 gives more factor of safety when estimating the failure loads, thus it is more conservative that the other codes and design method. Whereas, the proposed design method give the closest prediction of predicted failure load to the experimental failure loads.

All design theoretical method and code of practice has their own usefulness. With more usage of reinforced slender column in the building industry, more research should be carried out to study the behaviour of slender concrete column.