Flexural capacity of steel‐FCB bar‐reinforced coral concrete beams

Abstract

Steel‐fiber composite bar (SFCB) is a new technique with steel core embedded into the fiber‐reinforced polymer (FRP) bars, which solve the shortcomings of poor ductility and low stiffness of FRP‐reinforced concrete members. Based on the experimental study, flexural behavior of a new type concrete, SFCB bars‐reinforced coral concrete beams, is investigated. The deflection, failure mode, tensile strain, and ultimate flexural capacity of this new type of concrete beam are studied in detail through a series four‐points bending tests. The results show that the failure process of SFCB‐reinforced coral concrete beam can be divided into three main stages: elastic, cracking, and failure. Because exterior layer of SFCB bar is able to continue to withstand tensile stress after its steel core yield, hence, the flexural rigidity and flexural capacity of the beams both increase. The flexural stiffness of SFCB bars‐reinforced coral concrete beams is also increased, and the load‐deflection relation is more or less nonlinear. By using SFCB bars, the stiffness of the beams can be increased by about 20%. However, under high stress state, the relative slip between the carbon fiber and the concrete as well as that between the steel core and the carbon fiber cause tensile stress loss which weakened the flexural resistance of the SFCB bar‐reinforced coral concrete beam. The bonding performance between the round surface steel core and the carbon fiber is obviously weaker than that of the threaded surface steel core, and the steel core slip is more likely to occur under the higher tensile stress. When Using ACI440.1R‐15 and GB50608‐2010 to calculate the flexural capacity of the SFCB beams, the ratios of the theoretical value and the measured value from tests are 1.07 and 1.12, respectively. By introducing two new factors k1 and k2, a formula was developed through modification of the existing ones from ACI440.1R‐15 and GB50608‐2010 to calculate the ultimate flexural capacity of SFCB bar reinforced concrete beam which agrees as high as 93–99% with the experimental results.

Experimental studies on flexural behavior of full iron tailings concrete beams

“…A two‐point symmetric loading was applied to conduct a four‐point bending test 38 . The bending shear length was 1080 mm and the length of the pure bending region of the beam was 1090 mm.…”

“…A two-point symmetric loading was applied to conduct a four-point bending test. 38 The bending shear length was 1080 mm and the length of the pure bending region of the beam was 1090 mm. Figure 4 shows the test setup and arrangement of the strain gauge on the rebar and surface of the concrete beams, respectively.…”

Mechanical properties and uniaxial constitutive model of fiber‐reinforced coral aggregate concrete

“…It leads to higher costs and longer construction periods 2,3 . The use of coral fragments and seawater near the islands to prepare concrete not only saves construction time, but also significantly reduces costs 4,5 . Therefore, it is necessary to prepare concrete according to the local conditions.…”

Experimental and numerical study of the flexural capacity of reinforced concrete Vierendeel beams

“…[17] The flexural capacity and other mechanical performance of RC beams strengthened by GFRP or FRP have recently been investigated. [18][19][20][21][22] The effect of small compressive axial force on the flexural ductility performance of both normal-strength and high-strength concrete beams was evaluated on the base of fullrange moment-curvature. [23] A practical design procedure for replaceable coupling beam, an innovative structural component, was proposed.…”