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

摘要

The modulus of elasticity of concrete (E-c) is an important factor in the design of RC structures.E(c)is also essential for engineers to estimate deflections and stiffness of RC members. The prediction and calculation ofE(c)in Taiwan are still referred to ACI318-14 or ACI363R-92. It was confirmed thatE(c)is usually overestimated due to smaller coarse aggregate amount and higher paste volume in Taiwan. To obtain preciseE(c), it is necessary to develop prediction equations that can reflect material characteristic of Taiwan. This study collects 1389 test data sets ofE(c)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 ofE(c-predict)- to-E(c-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 ofE(c-predict)- to-E(c-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 lowE(c)characteristics in Taiwan and can provide a more accurate estimation ofE(c)for normal-strength and high-strength RC member designs.