Quasi-Static and Fatigue Behavior of GFRP Bars Embedded In Concrete скачать в хорошем качестве

Quasi-Static and Fatigue Behavior of GFRP Bars Embedded In Concrete

Quasi-Static and Fatigue Behavior of GFRP Bars Embedded In Concrete: A Comparison Between Pull-Out Tests And Flexural Tests of Slabs Presented By: Christian Carloni, Case Western Reserve University GFRP bars are considered an alternative to steel for concrete reinforcement. This project investigated the fatigue behavior of GFRP bars embedded in concrete, studying bond behavior at material and structural scales. GFRP bars (12 mm [0.47 in.] nominal diameter) were embedded in concrete cylinders leaving a 50 mm [2 in.] protrusion at the free end and featuring different bonded lengths. Two types of GFRP bars with different surface treatment (lacquered and unlacquered) were used. Static tests were used to determine the bonded length required for cyclic pull-out tests, Cyclic tests at 1.5 Hz showed GFRP bar failure was possible at just 20% of their reduced tensile strength (0.8ffu) as prescribed in ACI 440.1R-15. Two full-scale slabs internally reinforced with unlacquered GFRP bars were tested using a four-point bending configuration. A quasi-static test was used as a control to determine the fatigue amplitude, considering the fatigue loading provided by the ACI 440.1R-15 document and the pull-out test results with cyclic loading presented in this work. Cyclic load between 10 kN [2.25 kips] and 40 kN [9 kips] at a 1.5 Hz frequency was applied up to 5 million cycles before a subsequent quasi-static test was conducted. The load range was determined using cross-section analysis to cycle the bars between 5% and 20% of their reduced tensile strength (0.8ffu). Both slabs ultimately failed due to shear failure, with cyclic loading having little impact on the slab compliance. Displacements of the load points and supports were measured using linear variable displacement transformers (LVDTs), while digital image correlation (DIC) was utilized to obtain the full-field displacement and strain in the central region of the slab. The strain and displacement fields from DIC were used to determine the opening of flexural cracks and relate it to the stress level in the GFRP bars. Handout: Quasi-Static and Fatigue Behavior of GFRP Bars Embedded In Concrete A Comparison Between Pull-Out Tests And Flexural Tests of Slabs