Experimental Study on Elastic Modulus of Steel Stub Columns Encased in RC Containing Steel Fibers

Abstract

Today the use of concrete and steel columns is expanding rapidly. Therefore, the importance of studying these types of columns and providing solutions to improve the performance of these columns, is considered very important. Elastic modulus is a key parameter employed to estimate the deformation of structures and structural members and is typically expressed in terms of the compressive strength. Understanding the modulus of elasticity of reinforced concrete steel columns (SRCs) containing steel fibers and especially their behavioral changes during axial load application is an important issue. This paper tries to evaluate four moduli of elasticity of reinforced concrete columns containing steel fibers (SRFC). To achieve this goal, 36 SRFC specimens were constructed and various types of modulus of elasticity including the initial modulus, the sequential modulus, the yield point modulus, and the peak point modulus were examined. The research variables include the shape of steel section (H-shaped and C-shaped volume ratio of steel fibers (0, 0.75, and 1.25%), and stirrup spacing (40, 65, and 130 mm). The results showed that the modulus of elasticity of the SRFC columns was affected by the shape. Thus, the modulus of elasticity of columns with H-shaped cross-section was higher than columns with C-shaped cross-section due to more confinement in this type of cross-section. Also, increasing the percentage of steel fibers in the concrete of these types of columns can, in addition to increasing the ductility, increase the modulus of elasticity of the column by an average of up to 6%. In addition, the distance of the arches has a very significant effect on the modulus of elasticity of this type of columns, so that with increasing the distance of the arches, the modulus of elasticity of the columns decreases (about 35%) sharply.