Abstract
The purpose of this study is to investigate and evaluate the feasibility of using high-performance fiber-reinforced cement composites (HPFRCC) to satisfy the requirement of transverse reinforcement in beam-column joint under seismic loads. The basic mechanical properties of the HPFRCCs are determined by compression, uniaxial tension, and direct shear tests. Four half-scale exterior beam-column connections are cast and tested under cyclic loads. The cracking patterns, hysteresis behavior, ductility, energy dissipation with damping characteristics and joint shear capacity of the HPFRCC beam-column connections are analyzed, investigated, and compared to the cyclic responses of normal concrete connections designed with/without seismic criteria of ACI. The test results revealed that HPFRCC connections considerably enhances shear and flexural capacity and also improved the deformation and damage tolerance behavior in post-cracking stage comparing to normal concrete connections in ultimate stages. Also, the failure mode of HPFRCC specimens changed from shear mode to flexural mode comparing to the connections without seismic details. Severe damages are observed in normal concrete connection designed without considering seismic criteria. Wide diagonal cracking and damage are observed on the designed NC connections under large cyclic displacement at drift 6%. However, in HPFRCC connections, joint remained intact without any cracks and damage until the test end. This implies that the shear stress requirement can be satisfied without any need to the transverse reinforcement in the HPFRCC joint.
Highlights
Beam-column connections in reinforced concrete structures experience significant shear stresses under lateral displacement induced by earthquakes
4.1 Mechanical Properties of HPFRCCUniaxial compressive and tensile stress–strain relationship for normal concrete and high-performance fiber-reinforced cement composites (HPFRCC) specimens are shown in (Fig. 16a, b) and specimen results obtained by direct shear test is shown in Fig. 16c as sliding
5 Conclusion The results of this study are presented with the aim of providing a better understanding about the strain hardening behavior in high-performance fiber reinforced cement composites using uniaxial compression test, uniaxial tension test, and direct shear test
Summary
Beam-column connections in reinforced concrete structures experience significant shear stresses under lateral displacement induced by earthquakes. This may cause severe connection damage and stiffness reduction in structure. The conditions for anchorage in the longitudinal reinforcement of the beam and column in the joints have been improved with the use of steel fiber reinforced concrete (Jiuru et al 1992) Since these materials exhibit softening tensile response after the formation of the first cracks, despite the prevention of premature damage, this will limit the ability to withstand large tensile stresses, making the FRC improper choice to replace the transverse reinforcement in beam column joints with high stress. The necessity of special transverse reinforcement with high energy dissipation and lower stiffness properties has been resolved (Saghafi et al 2016; Kim et al 2008)
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