Study of prediction equation for modulus of elasticity of normal strength and high strength concrete in Taiwan

Abstract

ABSTRACT The modulus of elasticity of concrete (Ec ) is an important factor in the design of RC structures. Ec is also essential for engineers to estimate deflections and stiffness of RC members. The prediction and calculation of Ec in Taiwan are still referred to ACI318-14 or ACI363R-92. It was confirmed that Ec is usually overestimated due to smaller coarse aggregate amount and higher paste volume in Taiwan. To obtain precise Ec , it is necessary to develop prediction equations that can reflect material characteristic of Taiwan. This study collects 1389 test data sets of Ec in Taiwan. By regression analysis with certain key parameters, such as silica fume, new and practical prediction equations based on ACI318-14 and ACI363R-92 are proposed. The proposed estimation formula improves the average value and the standard deviation of Ec-predict – to- Ec-test ratio of normal-strength concrete from 122% to 99%, and from 0.173 to 0.139, respectively; Similar observation can also be found relative to high-strength concrete (The average value of Ec-predict – to- Ec-test ratio of high-strength improves from 132% to 101%, and the standard deviation fell from 0.149 to 0.11). These equations reflect the low Ec characteristics in Taiwan and can provide a more accurate estimation of Ec for normal-strength and high-strength RC member designs.