RESEARCH ON KEY CONTROLLING FACTORS FOR DEFLECTION & CRACK OF GFRP REINFORCED CONCRETE BEAMS UNDER SERVICEABILITY LIMIT STATE

A series of problems about the behavior, mechanism and related controlling factors of GFRP reinforced concrete beams under serviceability limit state could not be ignored and need to be studied in depth. This paper focuses on the key factors to influence deformation and crack of GFRP reinforced concrete beams under serviceability limit state. Three groups of 1/3 scaled concrete beams (9 Pieces) reinforced by GFRP bars were stepwise loaded by self-balancing loading equipment. And the corresponding finite element models were adopted to compare with test results and develop parameters learning. It was revealed that the principal factors to control the serviceability limit state of GFRP reinforced concrete beams would include mean stress level of concrete section lower than 45%fc, mid-span deflection less than l(0)/250 and maximum crack width less than 0.5 mm. Under normal service condition, increase of reinforced ratios would obviously slow down stiffness degeneration of beams. It was also shown that, from test and FEA results of wide-flat beams, GFRP bars were not suitable for wide-flat beams.