BENEFITS OF USING STEEL FIBERS FOR IMPROVED STRUCTURAL PERFORMANCE IN NORMAL-STRENGTH SLAB AND ULTRA HIGH-STRENGTH COLUMN CONNECTIONS

摘要

Due to recent trends in the construction industry (i. e. , construction of larger and taller structures) , the need for high-strength concrete is increasing. However, structural investigation into the practical applications of high-strength concrete is not yet complete. Furthermore, because the construction industry is more frequently using columns constructed of considerably high strength like ultra-high-strength concrete (UHSC), the structural stability and safety of ultra-high-strength concrete columns as well as normal-strength concrete slabs need to be investigated for. In general construction of slab-column connections, the joint between the slab and the column is made with a lower grade concrete than the rest of the column. As such, when the ratio of the column concrete strength to the slab concrete strength is very high, this construction method cannot fully utilize the column's high strength because of weaknesses in the slab-column joint. In such a case, the high-strength concrete should be placed in the column-slab joint and further into the slab. This paper presents the structural characteristics of slab-column connections using ultra-high-strength concrete from compression and punching shear tests performed on three slab-column specimens and four isolated column specimens. In addition, steel fibers were added to enhance the ductility to the ultra-high-strength concrete placed in the immediate column regioa The beneficial effects of ultra-high-strength concrete and steel fibers on the punching shear capacity and transmission of column loads through slab-column connections are demonstrated.