Cyclic Flexural and Shear Performances of Beam Elements with Longitudinal Glass Fiber Reinforced Polymer (GFRP) Bars in Exterior Beam-Column Connections

Abstract

The objective of this study is to examine the effect of the poor anchorage length of glass fiber reinforced polymer (GFRP) bars used for longitudinal reinforcement on the flexural and shear performances of beam elements in exterior beam–column connections made using high-strength materials. Six exterior beam–column connection specimens were tested under reversal cyclic loads applied at the free-end of the beam. The selected strength categories of materials in the beam element were as follows: 35 MPa and 70 MPa for the design compressive strength of concrete, 400 MPa and 600 MPa for the yield strength of conventional longitudinal steel bars, and 800 MPa for the tensile strength of the GFRP bar. All the longitudinal steel bars of the beams satisfied the minimum requirements of the provisions of ACI 318–14, whereas all the longitudinal GFRP bars of the beam were linearly anchored into the column section, resulting in poor anchorage length, especially for the beam with the concrete compressive strength of 35 MPa. The flexure-governed beams with GFRP bars exhibited a greater increasing rate in displacement at the pre-peak state and did not display the plastic flow characteristic after the peak load when compared with companion beams with steel bars. The beams with GFRP bars possessed lower diagonal cracking strengths and shear capacities than the companion beams with steel bars although the shear capacities of the beams with GFRP bars could be conservatively predicted using the design equation of ACI 440.1R–15 provision. The low elastic modulus and elongation capacity of GFRP bars resulted in large displacements and brittle post-peak beam performances. Furthermore, the lack of anchorage length of GFRP bars in exterior beam–column connection significantly reduced the flexural strength and ductility of the beam element.

A New Proposal for the Shear Strength Prediction of Beams Longitudinally Reinforced with Fiber-Reinforced Polymer Bars

“…The low transverse stiffness of FRP rebars significantly reduces the component stemming from dowel action [5,7]. As a result, at the same longitudinal reinforcement area, the concrete member reinforced with FRP bars has a lower shear strength than the corresponding steel-RC member [13,14].…”

Numerical Simulation of the Bearing Capacity of Variotropic Short Concrete Beams Reinforced with Polymer Composite Reinforcing Bars

“…It should be noted that reinforced concrete, with all its advantages, also has several disadvantages, which are expressed in the high cost of raw materials, such as reinforcing steel, and the large weight of the created structures, products and buildings [ 7 , 8 , 9 , 10 , 11 , 12 ]. All this leads to the fact that modern scientists and engineers are developing, with a certain degree of success, new types of reinforcing elements, such as polymer composite reinforcement, which makes it possible to successfully solve the abovementioned tasks and problems [ 13 , 14 , 15 , 16 , 17 ]. However, it should be noted that, as has already been proven by us and other authors earlier, it is certainly impossible to achieve a significant solution to the problem and eliminate all risk factors by improving the reinforcing elements alone [ 18 , 19 , 20 , 21 , 22 , 23 ].…”

“…This condition indicates the importance of the process of designing bending elements reinforced with fiberglass reinforcement, considering both bending and shear. So, for example, in several works [ 7 , 8 , 10 , 16 , 30 , 45 ], the authors, through experimental studies and calculations, developed and proposed new recommendations for calculating the shear strength of beams longitudinally reinforced with fiberglass reinforcement. Oller at al.…”

Cyclic Behavior of High-Strength Lightweight Concrete Exterior Beam-Column Connections Reinforced with GFRP

“…In addition, it was determined that [21] under cyclic loads, the behavior of a GFRP reinforced frame could permit larger displacements than conventional RC frames. Experimentally, six exterior beam-column connections were seismically investigated to inspect the effect of the poor anchorage length of GFRP bars used as longitudinal reinforcement on the beam behavior [22] and it was established that the absence of anchorage length of GFRP bars in the connection considerably drop the beam's flexural strength and ductility. Recent studies [23][24][25] claimed that the current design codes have slight or no seismic provisions for connections reinforced with GFRP due to a shortage of data and investigations.…”