Investigation on modeling parameters of concrete beams reinforced with basalt FRP bars

Fiber-reinforced polymer(FRP)bars are widely used as internal reinforcement replacing the conventional steel bars to prevent from corrosion.Among the different types of FRP bars,basalt FRP(BFRP)bars have been used in different structural applications and,herein,three already tested concrete beams reinforced with BFRP bars are analyzed using three-dimensional(3-D)finite element analysis(FEA).The beams were tested in four-point bending.In the FEA the behavior of concrete is simulated using the^Concrete-Damaged Plasticity^^model offered in ABAQUS software.The research presented here presents a calibrated model for nonlinear FEA of BFRP concrete beams to predict their response considering both the accuracy and the computational efficiency.The calibration process showed that the concrete model should be regularized using a mesh-dependent characteristic length and material-dependent post-yield fracture and crushing energies to provide accurate mesh-size independent results.FEA results were compared to the test results with regard to failure load and crack patterns.Both the test results and the numerical results were compared to the design predictions of ACI 440.1R-15 and CSA S806-12,where CSA S806-12 seems to overestimate the shear strength for two beams.

Compressive and cyclic flexural response of double-hooked-end steel fiber reinforced concrete

Recent developments on high-performance double-hooked-end steel fibers have enhanced the wide applications of steel fiber reinforced concrete(SFRC).This study presents the compressive properties and the cyclic flexural performance of the SFRC that were experimentally examined.Three different double-hooked-end steel fibers at 0.25%,0.5%,0.75%,and 1%volume fractions were considered.All fiber types had similar length to diameter ratios,while the first two fiber types had similar anchorage mechanisms(4D)and tensile strength and the third type had different anchorage mechanism(5D)and a higher tensile strength.The increased volumetric ratio of the fibers increased the post-peak compressive strain(ductility),the tensile strength,and the cyclic flexural strength and cumulative energy dissipation characteristics of the SFRC.Among the 4D fibers,the mixtures with the larger steel fibers showed higher flexural strength and more energy dissipation compared to the SFRCs with smaller size fibers.For 1%steel fiber dosage,4D and 5D specimens showed similar cyclic flexural responses.Finally,a 3D finite element model that can predict the monotonic and cyclic flexural responses of the double-hooked-end SFRC was developed.The calibration process considered the results obtained from the inverse analysis to determine the tensile behavior of the SFRC.

Fragility assessment of wood sheathing panels and roof-to-wall connections subjected to wind loading

The performance of the wood-frame buildings after tornadoes has shown that the majority of the wind damage resulted from building envelope failure most typically due to the loss of the roof.To assess the performance and the reliability of low-rise wood-frame residential buildings with a focus on the roofs,fragility analysis can be used to estimate the probability of failure of a roof when constructed with specified nails and sheathing sizes.Thus,this paper examines the fragility of specific types of nails,roof-to-wall(RW)connection details,and sheathing sizes based on the damaged roofs that were previously assessed in the Dunrobin area in Ottawa(Ontario)that was hit with an Enhanced Fujita(EF3)tornado on September 21,2018.The presented fragility analysis considers four scenarios,including different sheathing and nail sizes.Dead loads,wind loads,and resistance on the sheathing panels were compiled and analyzed to determine the failure of the examined roofs.The eight fragility models suggest that the safest roof sheathing(RS)is the 1.22 m×1.22 m sheathing panel with 8 d nails,and the safest RW connections is achieved by using H2.5 hurricane clips.