Shear Design Method Of GFRP Reinforced Concrete Beams Controlled By Diagonal Crack Width

Non-corrosive materials-Glass fiber reinforced polymers(GFRP)are now used as reinforcement for concrete structures to extend the service life of concrete structures and reduce maintenance costs.With different physical properties of steel bars——GFRP bars,with high tensile strength,low elastic modulus,and anisotropic material properties lead to low shear strength and have brittle fracture characteristics;when GFRP bars are used as stirrups,these things happen in the bending section of the stirrups,for the stress being too large and the fiber reinforcements broken.At the same time,the GFRP reinforced concrete beams will produce very wide diagonal cracks in the shear test.It is because of the above reasons that the diagonal crack width of the GFRP reinforced concrete beam may exceed the specified limit value in the component load stage.For building structures,deformation of the components under normal use will significantly affect the comfort of use.The research on the shear cracking resistance of GFRP reinforced concrete has rarely been carried out at home and abroad.Only the qualitative research on some corresponding oblique cracks has been rarely used as the design study of the width of oblique cracks.Therefore,there is an urgent need to explore this aspect.The main work of this paper is to study the development of diagonal cracks in GFRP reinforced concrete beams,and to design the structure with diagonal crack width as the design index of GFRP reinforced concrete members.The corresponding design theory and formula are supplemented by finite element analysis to qualitative the parameters of study.Therefore,this paper is going to,1)Establish a finite element analysis model.A multi-group and multi-parameter finite element analysis scheme was designed based on the parameters affecting stirrups,to establish a simulation model of a GFRP reinforced concrete beam,and the shear performance of the GFRP reinforced concrete beam was performed.Influence parameter factor analysis.2)Discuss the limit of oblique crack width,and obtain the corresponding strain value of stirrup as the design standard.With reference to the research status of diagonal crack width and GFRP stirrup strain at home and abroad,the relationship between oblique crack width and stirrup strain value of the GFRP reinforced concrete beam is obtained,and the GFRP reinforced concrete shear member is deduced under normal use.Strain design value.3)Validate the stirrup strain value of the design of the GFRP reinforced concrete beam.All aspects of shear resistance of GFRP reinforced concrete beams were tested and verified by finite element method and comparison,through 6 test results and 5 finite element model results for detailed analysis,parameter comparison.4)Shear design method for GFRP reinforced concrete beams in normal use.Based on the existing shear test of 81 non-stretched GFRP reinforced concrete beams and 12 GFRP reinforced concrete beams,the calculation formula for the normal use of GFRP reinforced concrete beams was established,and the semi-theoretical half was obtained based on the GFRP stirrup strain limits.Experienced GFRP rib design method.