Cyclic Behavior of High-Strength Hook-Ended Steel Fiber Reinforced Concrete Exterior Beam-Column Joints
Date Issued
2016
Date
2016
Author(s)
Su, Wei-Ru
Abstract
In recent years, high strength materials are used more and more generally. For example, they were used to save consumption of materials and reduce weight of members in New RC Project. However, high strength concrete is too brittle. It will lose strength rapidly when failure occurs, which leads to the obstacle of application due to the concern of safety. In Taiwan, which is in the seismic region, structures need to be designed with sufficient toughness and ability of seismic restraint. Using high transverse reinforcement ratio arrangement is the general way. However, for beam-column joint, which is the connection of longitudinal bars of beam and column, intensive transverse reinforcement arrangement will lead to construction difficulty. According to many experiment results, adding steel fiber in concrete can obviously enhance toughness, tensile strength and shear strength of concrete and prevent cover spalling in the early stage so that it could replace the role of transverse reinforcements to solve the congestion problem. The objective of the study is to investigate the feasibility of casting high strength steel fiber concrete in beam-column joints to replace parts of transverse reinforcements. This study aims to propose suggestions of designing reinforcement detailing. Four full-scale exterior beam-column joints, including two specimens with intensive stirrups and two specimens cast with steel fiber concrete without any stirrup, are tested. The specimens are under low and high axial load ratio at 0.1 and 0.45, respectively. Test results indicate that specimen cast with steel fiber concrete performs as good behavior as specimen with intensive transverse reinforcements on failure mode, displacement ductility, energy dissipation and crack width control under low axial load. However, under high axial load, the specimen cast with steel fiber concrete fails earlier than specimen with stirrups due to lack of confinement. Test results of all specimens attain requirements, it means using steel fiber concrete to substitute stirrups is feasible. It is still proposed to use small amount of stirrups to enhance ability of confinement in beam-column joints.
Subjects
Steel fiber
Exterior beam-column joint
Axial load ratio
Type
thesis
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