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

Abstract

Using lightweight reinforced concrete beams with glass fiber bars (GFRP) is one approach for achieving the requirement seismic design idea of “strong-columns weak-beams”. Twelve full-scale normal-strength concrete (NC with fc` = 32 MPa) and high-strength lightweight concrete (HSLWC with fc` = 42, 49 and 52 MPa) exterior beam-column joints have been tested under cyclic loadings. The beams were reinforced with conventional steel bars (CS) and GFRP using steel fibers (SF). The experimental joint shear force was compared with that estimated by some international codes such as the American Concrete Institute (ACI-19), the Egyptian code (ECP-07), and the New Zealand Code (NZS-06). Nonlinear finite element analysis (ABAQUS) was carried out. In the present study, three main parameters were explored (1) HSLWC, (2) GFRP ratios equal to 0.70%, 1.03% and 1.37%, (3) SF ratios equal to 0.0%, 0.75% and 1.50%. The findings of the experiment revealed that increasing the concrete strength from NC with conventional steel bars to high-strength lightweight concrete HSLWC (fc` = 42 MPa) with the same ratio of GFRP bars enhanced the first cracking load by about 25%. Increasing the SF ratio to 1.50% enhanced the failure load by 18–24% when compared with non-fiber specimens. The predicted joint shear strength estimated using the equations of the ACI 318-19 and ECP-07 are conservative for HSLWC exterior beam-column connection reinforced with GFRP bars but the predicted joint shear strength by using the equations of the NZS-07 is on the borderline for some cases. The finite element program ABAQUS can be used successfully to forecast the behavior of HSLWC beam-column connections reinforced with GFRP under seismic loadings.

Effects of Coal Gangue Coarse Aggregate on Seismic Behavior of Columns under Cyclic Loading

“…The displacement at the loading point of the column top is measured by LVDT-1, and LVDT-2 is used to record the horizontal displacement of the base to correct the column top displacement. LVDT-3/4 are two orthogonally arranged transducers used to measure the shear deformation in the plastic hinge area of the specimen [34]. The strains of the longitudinal bars and stirrups were measured by strain gauges (SG) glued to the surface of reinforcement, and the layout is shown in Figure 5b-d.…”

The Influence of the Flexural Strength Ratio of Columns to Beams on the Collapse Capacity of RC Frame Structures

“…RC frames designed before modern seismic codes sometimes collapse in SBWC failure mode, shear failure mode, soft story failure mode, and other nonductile failure modes [29][30][31]. Some research has been conducted to guarantee the SCWB failure mode by increasing the value FSRCB for steel frames [17,19,20,32] and RC frames [18,21,28,[33][34][35][36][37][38][39][40]. Based on the findings above, different FSRCB values ranging from 1.6 to 3.0 have been suggested to ensure the SCWB failure mode [21,28,32,[36][37][38].…”