Abstract
To investigate the crack resistance properties of high-performance fiber-reinforced concrete (HPFRC) beam-column joints, quasi-static tests of twenty-four beam-column joint specimens were performed. Test specimen variables included joint types, size effect, axial compression ratio, stirrup ratio in joint, web reinforcement, and noncorner vertical reinforcement across the joint region. The influences of these factors on the crack properties of HPFRC joints were analyzed. Test results showed that the shear strength at the crack of HPFRC exterior joints with shear failure was closer to the ultimate bearing capacity. The average ratio of the cracking shear force to the peak shear force was 0.631 for the exterior joint with shear failure, and the ratio was 0.527 for the interior joint with the same size. The size effect was observed in HPFRC joint specimens, and the average shear stress at the joint crack decreased with the increase of the joint specimen size. The increase of the axial compression ratio can improve the crack resistance properties (cracking strength and crack width) of HPFRC joints. Web reinforcement and noncorner vertical reinforcement across the joint region have no evident influence on the cracking strength of joints, but they significantly affect the distribution and width of cracks in the joint region. The formulas for calculating the cracking strength and crack width of HPFRC joints were proposed based on the test results.
Highlights
Cracks appear when the strain of concrete reaches the ultimate tensile strain. e ultimate tensile strain of normal concrete is small, so it is easy to crack. e crack is one of the important influence factors for durability of the structure
It is extremely important to control the crack of concrete in important structures or for components to ensure the durability of reinforced concrete structures, especially in coastal regions and salt lake regions with a serious corrosive environment
The climate is humid and hot, and the chloride ions in the sea penetrate in concrete in the form of sea fog and result in corrosion, which seriously affects the performance and service life of reinforced concrete structures [2]
Summary
Cracks appear when the strain of concrete reaches the ultimate tensile strain. e ultimate tensile strain of normal concrete is small, so it is easy to crack. e crack is one of the important influence factors for durability of the structure. E results showed that the cracking load of the steel fiber concrete joints was 50% higher than that of the normal concrete joints with the same reinforcement. Us, the use of steel fiber concrete can improve the crack resistance properties of RC members, and the high-performance fiber-reinforced concrete (HPFRC) with high cracking strain and super durability can be an effective method to solve the durability problems of reinforced concrete structures. Zheng et al [19] conducted tests of 14 reactive powder concrete beams with axial compressive strength of 102 MPa. e results indicated that the bending tensile cracking strain of the rectangular section RPC beam is 750 × 10−6 and the ultimate compressive strain is 5500 × 10−6, far higher than the normal concrete. It is very necessary to study the crack resistance properties and calculate the cracking load and crack width of HPFRC joints
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